Today's Message Index:
----------------------
1. 05:57 AM - Re: grounding to fuselage (Eric M. Jones)
2. 06:33 AM - Re: Re: grounding to fuselage (Robert L. Nuckolls, III)
3. 07:14 AM - Re: Re: grounding to fuselage (Mike Fontenot)
4. 08:49 AM - Re: Lightweight Aux Battery? (sonex293)
5. 08:52 AM - Re: Lightweight Aux Battery? (sonex293)
6. 10:16 AM - Re: [Probable SPAM] Re: Lightweight Aux Battery? ()
7. 12:55 PM - Essential Incident - Almost (Long) (Ed Anderson)
8. 01:14 PM - Re: Essential Incident - Almost (Long) (Sam Hoskins)
9. 01:46 PM - Re: Essential Incident - Almost (Long) (Matt Prather)
10. 02:11 PM - Re: Essential Incident - Almost (Long) (Kevin Horton)
11. 05:43 PM - Re: Essential Incident - Almost (Long) (Ed Anderson)
12. 05:43 PM - Re: Essential Incident - Almost (Long) (Ed Anderson)
13. 05:52 PM - Re: Essential Incident - Almost (Long) (Ed Anderson)
14. 07:02 PM - Re: Essential Incident - Almost (Long) (Bill Schlatterer)
15. 10:57 PM - Re: Essential Incident - Almost (Long) (Etienne Phillips)
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Subject: | Re: grounding to fuselage |
I suppose you could "get away with it" to use the airframe for grounding. But remember
that the "ground" connection does EXACTLY the same thing as the positive
conductor but backwards.
Wiring a tail light might be fine, but wiring the ground on a MAC/RAC trim box
will almost certainly cause a noisy bar graph indicator, and the desire to keep
down the loop resistance can be frustrated, and change with age. If you just
can't stop yourself, then at least don't use the airframe or tubes as a high
current ground for engine starting.
A customer of mine has an automobile built of steel. It has a battery in the trunk
and requires an additional ground conductor--or the engine won't start. Hmmmm.......
"When facing a decision, ask yourself: what would I do if I wasn't afraid?"
Russ Reeves
--------
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones@charter.net
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=246583#246583
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Subject: | Re: grounding to fuselage |
At 07:54 AM 6/3/2009, you wrote:
>
>I suppose you could "get away with it" to use the airframe for
>grounding. But remember that the "ground" connection does EXACTLY
>the same thing as the positive conductor but backwards.
>
>Wiring a tail light might be fine, but wiring the ground on a
>MAC/RAC trim box will almost certainly cause a noisy bar graph
>indicator, and the desire to keep down the loop resistance can be
>frustrated, and change with age. If you just can't stop yourself,
>then at least don't use the airframe or tubes as a high current
>ground for engine starting.
>
>A customer of mine has an automobile built of steel. It has a
>battery in the trunk and requires an additional ground conductor--or
>the engine won't start. Hmmmm.......
All of which goes to the system integration task
of deducing which devices are potential antagonists
(can be grounded about anywhere) and potential victims
(demand attention to wiring to avoid ground loop injection
of noise).
It's not a matter of "getting away with it". This
phraseology suggests an air of uncertainty or risk
for using the airframe as a ground. When accomplished
with a bit of study and understanding, then there is no
uncertainty, no risk and no wishful thinking for
"getting away with" anything.
>"When facing a decision, ask yourself: what would I do if I wasn't afraid?"
Perhaps the better question is: "What do I need to understand to
mitigate my unfounded fear?"
Bob . . .
---------------------------------------
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
---------------------------------------
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Subject: | Re: grounding to fuselage |
Maybe it should be "ungrounded fear".....
On Wed, Jun 3, 2009 at 7:30 AM, Robert L. Nuckolls, III <
nuckolls.bob@aeroelectric.com> wrote:
> nuckolls.bob@aeroelectric.com>
>
> At 07:54 AM 6/3/2009, you wrote:
>
>> emjones@charter.net>
>>
>> I suppose you could "get away with it" to use the airframe for grounding.
>> But remember that the "ground" connection does EXACTLY the same thing as the
>> positive conductor but backwards.
>>
>> Wiring a tail light might be fine, but wiring the ground on a MAC/RAC trim
>> box will almost certainly cause a noisy bar graph indicator, and the desire
>> to keep down the loop resistance can be frustrated, and change with age. If
>> you just can't stop yourself, then at least don't use the airframe or tubes
>> as a high current ground for engine starting.
>>
>> A customer of mine has an automobile built of steel. It has a battery in
>> the trunk and requires an additional ground conductor--or the engine won't
>> start. Hmmmm.......
>>
>
> All of which goes to the system integration task
> of deducing which devices are potential antagonists
> (can be grounded about anywhere) and potential victims
> (demand attention to wiring to avoid ground loop injection
> of noise).
>
> It's not a matter of "getting away with it". This
> phraseology suggests an air of uncertainty or risk
> for using the airframe as a ground. When accomplished
> with a bit of study and understanding, then there is no
> uncertainty, no risk and no wishful thinking for
> "getting away with" anything.
>
> "When facing a decision, ask yourself: what would I do if I wasn't
>> afraid?"
>>
>
> Perhaps the better question is: "What do I need to understand to
> mitigate my unfounded fear?"
>
>
> Bob . . .
>
> ---------------------------------------
> ( . . . a long habit of not thinking )
> ( a thing wrong, gives it a superficial )
> ( appearance of being right . . . )
> ( )
> ( -Thomas Paine 1776- )
> ---------------------------------------
>
>
--
Mike
===============================
Mike Fontenot
Apex Consulting & Services LLC
Lakewood, Colorado
303 / 731-6645
mikef AT apexconsultingservices DOT com
===============================
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Subject: | Re: Lightweight Aux Battery? |
Bob,
I went back and looked at my existing battery, the Odyssey PC625. From the MFG
datasheets the battery can provide 13.6 Amps for one hour. After recalculating
my load with non-essentials turned off, I 'm currently at 5.4 amps and with
the addition of the EFI system would bring the current requirements to 13.1 Amps.
So,with my current system I could run for about 1 hour, which was my datapoint.
I guess my main concern was the even of a battery failure and/or PM Alternator
failure. Based on you're comments, it sounds like a vary rare occurrence.
I've been unhappy with the fuel delivery methods of the AeroCarb which I'm currently
using and the Bing. Both can be setup to operate "OK", but nether can setup
to operate great across the entire power spectrum. There is also the reason
of just wanting to do it from a technical standpoint.
So it looks like I may not need the complexities of the AUX battery.
--
Michael
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=246610#246610
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Subject: | Re: Lightweight Aux Battery? |
>From the items you quoted, I guess you've guessed I'm looking at EFI. There is
already someone in your neck of the woods that has done this modification and
has indicated he is very pleased with the outcome.
--
Michael
Peter Eedy wrote:
> Hi Michael
> What sort of upgrade do you have planned for your 3300?
> Enquiring minds, thinking likewise, would like to know?
> All the best.
>
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=246611#246611
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Subject: | Re: Lightweight Aux Battery? |
Mike,
If it's an option, keep the same battery and add a second alternator.
True, you could go with a bigger battery, but my engine is bigger than
yours and the 680 works fine. A second alt is easy (unless mounting is a
problem), more reliable than batteries (many will argue that one, but my
auto store always sells more batteries than alternators mmmm...) and
adds less weight. Better to be up there with 2 alternators than two
batteries worth diddle. You do need enough juice to keep the alternator
excited and that varies with the brand.
I've got two alternators, one battery, dual EI and plenty of
reliability. If I shut the alternators off, my machine runs for almost
an hour on the 680 with dual EI before falling out of the sky (tested on
ground only).
This is a very old argument and everyone has their own opinion about
his/her mission. The fact that we are all still here talking about it,
lends itself to the idea that either solution is viable and reliable as
long as you respect the limitation of each.
Glenn
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of
sonex293
Sent: Wednesday, June 03, 2009 11:50 AM
Subject: [Probable SPAM] AeroElectric-List: Re: Lightweight Aux Battery?
>From the items you quoted, I guess you've guessed I'm looking at EFI.
There is already someone in your neck of the woods that has done this
modification and has indicated he is very pleased with the outcome.
--
Michael
Peter Eedy wrote:
> Hi Michael
> What sort of upgrade do you have planned for your 3300?
> Enquiring minds, thinking likewise, would like to know?
> All the best.
>
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=246611#246611
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Subject: | Essential Incident - Almost (Long) |
It was suggested by one of the aeroelectric list members, Sam Hoskins, that
the following report of an incident I had on a recent trip be posted to the
AeroElectric list for obvious reasons - once you read it.
I have an all-electric Rv-6A with over 10 years and close to 500 hours on
it. I based the electrical system roughly one of Bob's excellent designs.
It initially had one alternator and two batteries, but removed the second
battery approx 5 years ago - but, I did make one modification to the design
that I almost had cause to regret.
So needless to say, but I will, responsibility for design and incident is
totally mine.
But, to get on with the tale
One the way to Texas I had an incident that ended up in with me and aircraft
making a 7 mile engine-out glide into Craig Field (Selma, Alabama). NO! It
was not fault of the engine or even the subsystems. But, the complete
answer is not provided until after my litany of the conditions and symptoms
- can you figure it out?
I took off on Thursday (28 May 2009) AM from North Carolina planning on
stopping in Mississippi to join up with two friends. After spending the
night there, we all three would then head for Texas. But, the weather (as
you are aware) has been laying over the southeast for days with rain and
more rain - but I launched into it anyway as past Atlanta, GA things were
forecast to improve..
Other than dodging lines of clouds and a bit of scud running, but not much,
I landed at Alexandria City to the southwest of Atlanta, GA to take on fuel.
I then climbed back in and fire it up and took off.
I noticed that during climb-out the engine would occasionally miss and
thought the fuel might have had a bit of water in it, but was not really
concerned. So I fly on for approx another 45 minutes and had just passed
Selma, Alabama and old Craig Air Force base, and turned west toward
Mississippi, when more symptoms began to occur.
It started to act like a case of SAG (fouled spark plugs) where the rpm will
drop a bit - not dangerous - just nerve racking. But, shortly things began
to go beyond the SAG symptoms, so I though I might have an injector problem
(like one sticking open or not opening at all). Since our injectors are in
pairs, I tried turning one pair off figuring if things got better, then
that pair might have a bad injector.
So I turned off one pair and sure enough the symptoms abated a bit (more on
this later) so I figured I had a bad injector in that pair. To be certain I
turned this "bad" pair back on and turn off the "good" pair expecting the
symptoms to really get bad as I would now be running on only the "bad" pair
- much to my surprise when I turned off the "good" pair - the symptoms also
abated. So that indicated it was not an injector problem - but what?
About this time, I decided to turn the aircraft back around toward Craig
Field and dodging clouds headed back with the engine progressively getting
worst. It appeared to be a fuel problem (and while that is ultimately the
subsystem affected - it was not the root cause). The fuel pressure was
ranging from zero to 80 psi, other electrical things were also misbehaving.
I check the voltmeter thinking perhaps the alternator had died - but it
showed 14 volts. So back to the fuel system.
Finally, the engine just stops with the prop standing still - like a hood
ornament, I'm at around 4500-5000 MSL at this point having lost some
altitude dodging a cloud (good old GPS just kept pointing to Craig Field).
At that time I am 6-7 miles out from Craig Field at 4500 msl with a stopped
prop, a crippled seat cushion and a dry mouth. Yes, I've been there before,
but I don't think you ever get "use" to it. I recalled thinking -". things
just can't get worst." when they very shortly and suddenly - did.
I keyed the radio and made a call to Craig Field at 4 miles on the GPS but
before I could get their reply, I heard a "CLANK" (without the engine
running you can hear things like that) like a relay springing open (it was)
and the entire panel goes dead!!!! No radio, no engine instruments, not
even a stinking LED was lit - only the battery powered GPS. Can you spell
"total electrical failure?" Talk about a lonely feeling - amazing how
comforting having lights on and radio - you could almost convince yourself
this was just a practice engine-out landing, but not when the panel goes
dark. No engine gauges, no radio, nada!
Well not being one inclined to panic (but I seriously considered it for a
moment {:>)), I continued toward Craig field - I mean like there were lots
of other alternatives. Well Once again I found myself in the "fortunate
position" of being too high, too much altitude. So I put in 40 degs of flaps
to steepen my rate of descent. But, then I decided this time that rather
than do the 360 I had done on a previous Incident to lose "excessive"
altitude, I would try to glide - a more or less - regular traffic pattern.
However, I neglected to remember to retract the flaps. So I found myself on
the downwind around mid-field at pattern altitude (which felt normal) until
I suddenly realized that you CAN NOT maintain that pattern altitude without
an engine!!! (and particularly with 40 deg of flaps deployed - flaps and
trim are manual) Duh!
I knew I could never make it to the far end of the runway before turning
base (toward the runway) and I was losing altitude at the rate of 400-500
fpm, so I started my turn immediately. To make matters a bit worst - I had
been paralleling the runway on the downwind leg a bit too close in - must
have been the comforting feeling of being close to safety. This position
naturally required a tighter turn and as I turned I saw I was likely to
overshoot the runway and land in the grass. So I though I need to steepen
this turn further (Yep! COFFIN CORNER was calling), but fortunately glanced
at my airspeed indicator - to see it only registering 80 MPH and my rate of
descent (normally 400-500 feet per minute) up to over 1000 feet per minute.
The seat cushion suddenly vanished from this universe.
But the REAL danger in this situation, as you all know, is your airspeed
gets low, you are in a steep bank which greatly raises the stall speed -
meaning at 80 mph you are close to a stall in a steep turn while your are
not in straight and level. So I immediately straighten out of the turn -
the little voice saying "better to land in the grass than get their concrete
runway all messed up". So the immediate danger of a stall was adverted, but
I was still pointed toward the ground with a sink rate twice as high as
normal (and I've manage a few hard landings even with a normal sink rate).
Fortunately, the runway was now under my nose rather than grass.
The hardest thing to do when you are sinking at a 1000 fpm a couple hundred
feet above the ground (with your nose already pointed at the ground) is to
push the stick forward steeping the dive even more. But, I manage to do
that and picked enough air speed and energy to flair to a nice touch down -
not even a bump. I've always been amazed at what total concentration does
to improve you landing {:>).
Rolled to the end of the runway and had energy to roll off onto the taxiway.
Got out, check under the aircraft for any evidence of leaks and started
pulling the aircraft toward the far -off - hangar which had an airplane
parked in front of it. A nice looking young woman comes riding a bicycle
out to meet me. Hopped off and holding out her hand said "Hi I'm Angie,
looks like we'll be spending time together" - so things were starting to
look up {:>)
So pulled the aircraft in to the hangar where the mechanic came over and ask
what the problem was. Well, I looked at the volt meter and it said the
battery was dead. Mechanic put on a battery charger and announced "Yep! The
battery is dead". So we both concluded that the alternator must have failed
and not being able to replenish the drain on the battery by all the
electrical systems such as fuel pumps, injectors, ignition coils, etc had
drained the battery.
However, there were a few problems with the analysis of a failed alternator.
First, the low voltage warning light never came on to warn of an alternator
problem, 2nd I never notice the voltmeter showing anything other than what
it should for alternator voltage - like around 14 volts. While checking the
voltage after the Mechanic had charged the battery, I noticed down below
that the "essential bus" switch was in the battery rather than the
alternator position, so flicked it back to the alternator position figuring
I must have accidentally kicked it while getting to some stuff in the
baggage compartment of my RV-6A.
It was getting late and being a bit tired not to mention stressed, I needed
to get a rental car and a motel for the night. Did that, eat dinner and
went to bed after sitting down and drawing out a problem tree with the
entire major elements of the electrical system.
So next morning I show up at the hangar early and met Ben, the mechanic, the
battery had received a charge of only 45 minutes the evening before, So I
suggested we charged it for another hour and try to start the aircraft. Ben
suggested a real stress test of the battery and NOT charge it anymore. Made
sense, so we rolled the aircraft out of the hangar. I hopped in, threw a
half dozen switches and punched the starter button. The engine started on
the first prop blade rotation - so the battery was clearly OK. The engine is
humming like a top. So I looked over at the voltmeter expecting it to
show only around 12.8 volts instead of the 14 volts a functioning alternator
would produce. Much to both my and Ben's surprise the alternator voltage
read 14 volts. We loaded the alternator by turning on the both l00 watt
landing lights, all fuel pumps, the pitot heat, etc. The alternator voltage
only drops perhaps 0.4 volts clearly indicating the alternator could carry
the load and was OK.
So here I am - battery is OK, alternator is OK - engine is purring normally,
so clearly this was all a figment of my deteriorating brain cells. I loaded
up the aircraft and launched to do a few circuits of the airport - I did so
and all was operating normally and so I radio them I was head onward to
Texas. While flying (with my only functional eyeball on the voltmeter), my
mind could not let go of the problem and finally the light bulb came on.
The essential bus switch had (for my entire 10 + years of flying)always been
in the alternator position. The purpose of this switch is, of course, to
isolate the battery from the alternator should the alternator fail - to
prevent an alternator problem from draining the battery. So in event of an
alternator problem, you move the switch from alternator to battery. Its
call the essential bus because you only have the essential things drawing
from the battery so you wont' drain it as quickly. The idea is to give you
time (generally around 30 minutes) to find a safe place to land in case of
alternator failure.
Well, at some point I had either (not paying attention) turned the switch to
battery thinking I was turning the voltmeter switch to battery(more on that
below) - or accidentally had move the switch from alternator to battery
without noticing it by kicking it, etc. However, it was sort of protected
in its position from accidental activation. It must have happened during
refueling - as I got approx 45 minutes down the road on the battery after
take off before quality battery time started to deteriorate. As the battery
voltage fell due to the load (and no alternator link to replenish it),
electrical things (mainly computers first) started acting up until they
could not longer run the engine. The injectors would not open fully, etc.
Then as the voltage level further decreased, the master relay which the
battery held closed and which connected the (fully functional) alternator to
the rest of the electrical system - opened up and removed ALL power from the
electrical system. So no radio, no gauges, etc.
Oh, another little factor that may have contributed, the voltmeter has a
tiny toggle switch by it marked ALT BAT1 BAT2 for checking alternator
battery 1 and battery 2 (which I no longer fly with) voltages. Down below
It a couple of inches and off to the right is the essential bus normal size
toggle switch - also marked ALT BAT1 BAT1. I normally never touch it and
don't even think about it. But I could have reached for the voltmeter
toggle thinking to check my battery voltage (which I do as a regular thing)
and perhaps distracted by something reached a bit further down and instead
moved the essential bus switch from Alternator to Battery causing this
entire event. I know that I did not consciously do it. So it is either
accidental or absence minded activation - either way ends with the same
results {:>)
Now it became clear why it didn't matter which pair of fuel injectors I
turned off - turning off either pair improved the situation because it
slightly reduced the electrical load by a few amps - and the engine ran
slightly better for a few moments. The same thing had happened when turning
off one of the EFI fuel pumps - but what threw me was the alternator voltage
continued to be normal during this.
After I knew the cause (switch in wrong position), I decided the problem was
fixed so no reason to return to NC, and I just continued on to Texas.
I know some of you may think that removing my second battery was a mistake -
but, consider this, having another battery could have meant I would have
been much further from a suitable airfield before they both went south. On
the other hand, it might have caused me to at least think to throw the
essential bus switch to the second battery and have the Light bulb come on.
Who really knows. But, I have in mind a simply addition to my electrical
circuit that should help in the future.
I do want to state that this time when the problems started I DID switch
fuel tanks - but naturally it had no effect because this time it turned out,
it was not a fuel problem - not the root cause at least.
So what are the lessons learned:
1. Put EVERY critical switch on your before-takeoff Check list
2. Perhaps put a guard around such critical switches to force conscious
activation
3. Don't (hard not to) get overly focused on what you think is the
problem - consider other possibilities. I thought it was a fuel problem (I
even switched fuel tanks this time) - it turned out to be electrical in its
root cause.
4. While the fuel pressure was jumping all over the place and the EGT
was erratic and engine surging strongly indicating a fuel problem - the
ultimate cause was electrical. Once the voltage got below a certain point
the EC2 computer was still trying to pull the injectors open, but with the
voltage so low it could not do it properly.
5. When the battery voltage dropped below a certain point, the master
relay released and removed the alternator from the electrical system and the
panel went dark - even though the alternator was still working
6. Immediately turn to the nearest airfield when serious problems occur
- THEN work on fixing them. I only delayed for perhaps 2-3 minutes, but
that could have made a difference.
7. Watch out for Coffin Corner turn when turning base to final -
airspeed really bleeds off fast with no engine pulling you along (and
especially with flaps deployed!)
8. IF you change your mind about landing approach type - remember to
reconfigure your aircraft for the last decision - I had left my flaps
deployed when I should have remembered to retracted them. Did that help
prevent a Coffin Corner stall and spin or would it have put me closer to it?
9. You must increase airspeed over the wing to get the sufficient
energy to over come a high sink rate. Pulling back on the stick when the
ground is staring you in the face is the natural reaction - but, pushing
forward to lower the nose is the correct action - providing of course you
have sufficient altitude!
10. Battery life - I had a two year old 680 odyssey battery which I
maintain a trickle charge on whenever I'm not flying. With two EFI fuel
pumps, boost pump, injectors, coils, EC2 and radio and just having started
the engine before take off - this battery lasted 55 minutes. Well, the last
5 minutes were not quality battery time. So in my case, 30 minutes appears
to be a very realistic battery life. In fact, had I turned off one EFI pump
and the boost pump would have gained a few more miles. But, if I had
recognized the need to turn them off at that time (I normally turn them off
at cruise altitude), then I would have known how to "fix" the problem.
11. I've decided to add a Schokkty diode between my essential bus and
the alternator - so that as long as the alternator is producing sufficient
voltage, then the battery will be getting some charge to replace the drain.
I've also decided to make that switch position a check-list item.
So what it boils down to - if I had recognized early on that it was an
electrical problem and not focused so much on the fuel system, I may have
noticed the essential bus switch in the wrong position. Force yourself to
examine other possible causes (easy to say - harder to do).
NEVER, NEVER forget that flying the airplane is the first and only priority
in this type of situation
NEVER, NEVER forget that saving your butt is the ultimately end-all
priority. When I decided that landing on the grass was preferable to
putting a hole in their concrete - I may have made a life-saving decision.
So that's my story and I'm sticking to it.
Fly safe, guys!!
Ed
Ed Anderson
Rv-6A N494BW Rotary Powered
Matthews, NC
eanderson@carolina.rr.com
<http://www.andersonee.com> http://www.andersonee.com
<http://www.dmack.net/mazda/index.html>
http://www.dmack.net/mazda/index.html
http://www.flyrotary.com/
<http://members.cox.net/rogersda/rotary/configs.htm>
http://members.cox.net/rogersda/rotary/configs.htm#N494BW
<http://www.dmack.net/mazda/index.html>
Message 8
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Subject: | Re: Essential Incident - Almost (Long) |
Ed - great story. Just out of curiosity, where is the essential bus switch
located? Is it plainly in your field of vision or do you have to turn your
head to see it?
Cockpit ergonomics are a huge challenge.
Sam Hoskins
www.samhoskins.blogspot.com
On Wed, Jun 3, 2009 at 2:53 PM, Ed Anderson <eanderson@carolina.rr.com>wrot
e:
> It was suggested by one of the aeroelectric list members, Sam Hoskins,
> that the following report of an incident I had on a recent trip be poste
d
> to the AeroElectric list for obvious reasons ' once you read it.
>
>
> I have an all-electric Rv-6A with over 10 years and close to 500 hours o
n
> it. I based the electrical system roughly one of Bob=92s excellent desig
ns.
> It initially had one alternator and two batteries, but removed the secon
d
> battery approx 5 years ago ' but, I did make one modification to the d
esign
> that I almost had cause to regret.
>
>
> So needless to say, but I will, responsibility for design and incident
is
> totally mine.
>
>
> But, to get on with the tale
>
>
> One the way to Texas I had an incident that ended up in with me and
> aircraft making a 7 mile engine-out glide into Craig Field (Selma,
> Alabama). NO! It was not fault of the engine or even the subsystems. B
ut,
> the complete answer is not provided until after my litany of the conditio
ns
> and symptoms ' can you figure it out?
>
>
> I took off on Thursday (28 May 2009) AM from North Carolina planning on
> stopping in Mississippi to join up with two friends. After spending the
> night there, we all three would then head for Texas. But, the weather (a
s
> you are aware) has been laying over the southeast for days with rain and
> more rain ' but I launched into it anyway as past Atlanta, GA things we
re
> forecast to improve..
>
>
> Other than dodging lines of clouds and a bit of scud running, but not muc
h,
> I landed at Alexandria City to the southwest of Atlanta, GA to take on
> fuel. I then climbed back in and fire it up and took off.
>
>
> I noticed that during climb-out the engine would occasionally miss and
> thought the fuel might have had a bit of water in it, but was not really
> concerned. So I fly on for approx another 45 minutes and had just passed
> Selma, Alabama and old Craig Air Force base, and turned west toward
> Mississippi, when more symptoms began to occur.
>
>
> It started to act like a case of SAG (fouled spark plugs) where the rpm
> will drop a bit ' not dangerous - just nerve racking. But, shortly thi
ngs
> began to go beyond the SAG symptoms, so I though I might have an injector
> problem (like one sticking open or not opening at all). Since our inject
ors
> are in pairs, I tried turning one pair off figuring if things got better
,
> then that pair might have a bad injector.
>
>
> So I turned off one pair and sure enough the symptoms abated a bit (more
on
> this later) so I figured I had a bad injector in that pair. To be certai
n I
> turned this =93bad=94 pair back on and turn off the =93good=94 pair expec
ting the
> symptoms to really get bad as I would now be running on only the =93bad
=94 pair
> ' much to my surprise when I turned off the =93good=94 pair ' the sym
ptoms also
> abated. So that indicated it was not an injector problem ' but what?
>
>
> About this time, I decided to turn the aircraft back around toward Craig
> Field and dodging clouds headed back with the engine progressively gettin
g
> worst. It appeared to be a fuel problem (and while that is ultimately the
> subsystem affected - it was not the root cause). The fuel pressure was
> ranging from zero to 80 psi, other electrical things were also misbehavin
g.
> I check the voltmeter thinking perhaps the alternator had died ' but it
> showed 14 volts. So back to the fuel system.
>
>
> Finally, the engine just stops with the prop standing still - like a ho
od
> ornament, I=92m at around 4500-5000 MSL at this point having lost some
> altitude dodging a cloud (good old GPS just kept pointing to Craig Field)
.
> At that time I am 6-7 miles out from Craig Field at 4500 msl with a stopp
ed
> prop, a crippled seat cushion and a dry mouth. Yes, I=92ve been there be
fore,
> but I don=92t think you ever get =93use=94 to it. I recalled thinking
'=93=85 things
> just can=92t get worst=85=94 when they very shortly and suddenly - did.
>
>
> I keyed the radio and made a call to Craig Field at 4 miles on the GPS bu
t
> before I could get their reply, I heard a =93CLANK=94 (without the engine
> running you can hear things like that) like a relay springing open (it w
as)
> and the entire panel goes dead!!!! No radio, no engine instruments, not
> even a stinking LED was lit ' only the battery powered GPS. Can you sp
ell
> =93total electrical failure?=94 Talk about a lonely feeling ' amazing
how
> comforting having lights on and radio ' you could almost convince yours
elf
> this was just a practice engine-out landing, but not when the panel goes
> dark. No engine gauges, no radio, nada!
>
>
> Well not being one inclined to panic (but I seriously considered it for a
> moment {:>)), I continued toward Craig field ' I mean like there were l
ots
> of other alternatives. Well Once again I found myself in the =93fortunat
e
> position=94 of being too high, too much altitude. So I put in 40 degs of
flaps
> to steepen my rate of descent. But, then I decided this time that rather
> than do the 360 I had done on a previous Incident to lose =93excessive=94
> altitude, I would try to glide - a more or less - regular traffic pattern
.
>
>
> However, I neglected to remember to retract the flaps. So I found myself
> on the downwind around mid-field at pattern altitude (which felt normal)
> until I suddenly realized that you CAN NOT maintain that pattern altitude
> without an engine!!! (and particularly with 40 deg of flaps deployed '
> flaps and trim are manual) Duh!
>
>
> I knew I could never make it to the far end of the runway before turning
> base (toward the runway) and I was losing altitude at the rate of 400-500
> fpm, so I started my turn immediately. To make matters a bit worst - I
had
> been paralleling the runway on the downwind leg a bit too close in ' mu
st
> have been the comforting feeling of being close to safety. This position
> naturally required a tighter turn and as I turned I saw I was likely to
> overshoot the runway and land in the grass. So I though I need to steepe
n
> this turn further (Yep! COFFIN CORNER was calling), but fortunately glan
ced
> at my airspeed indicator - to see it only registering 80 MPH and my rate
of
> descent (normally 400-500 feet per minute) up to over 1000 feet per minut
e.
> The seat cushion suddenly vanished from this universe.
>
>
> But the REAL danger in this situation, as you all know, is your airspee
d
> gets low, you are in a steep bank which greatly raises the stall speed -
> meaning at 80 mph you are close to a stall in a steep turn while your are
> not in straight and level. So I immediately straighten out of the turn
'
> the little voice saying =93better to land in the grass than get their con
crete
> runway all messed up=94. So the immediate danger of a stall was adverted
, but
> I was still pointed toward the ground with a sink rate twice as high as
> normal (and I=92ve manage a few hard landings even with a normal sink rat
e).
> Fortunately, the runway was now under my nose rather than grass.
>
>
> The hardest thing to do when you are sinking at a 1000 fpm a couple hundr
ed
> feet above the ground (with your nose already pointed at the ground) is t
o
> push the stick forward steeping the dive even more. But, I manage to do
> that and picked enough air speed and energy to flair to a nice touch down
'
> not even a bump. I=92ve always been amazed at what total concentration d
oes
> to improve you landing {:>).
>
>
> Rolled to the end of the runway and had energy to roll off onto the
> taxiway. Got out, check under the aircraft for any evidence of leaks an
d
> started pulling the aircraft toward the far 'off ' hangar which had a
n
> airplane parked in front of it. A nice looking young woman comes riding
a
> bicycle out to meet me. Hopped off and holding out her hand said =93Hi I
=92m
> Angie, looks like we=92ll be spending time together=94 ' so things were
starting
> to look up {:>)
>
>
> So pulled the aircraft in to the hangar where the mechanic came over and
> ask what the problem was. Well, I looked at the volt meter and it said t
he
> battery was dead. Mechanic put on a battery charger and announced =93Yep!
The
> battery is dead=94. So we both concluded that the alternator must have f
ailed
> and not being able to replenish the drain on the battery by all the
> electrical systems such as fuel pumps, injectors, ignition coils, etc had
> drained the battery.
>
>
> However, there were a few problems with the analysis of a failed
> alternator. First, the low voltage warning light never came on to warn o
f
> an alternator problem, 2nd I never notice the voltmeter showing anything
> other than what it should for alternator voltage ' like around 14 volts
.
> While checking the voltage after the Mechanic had charged the battery, I
> noticed down below that the =93essential bus=94 switch was in the battery
rather
> than the alternator position, so flicked it back to the alternator positi
on
> figuring I must have accidentally kicked it while getting to some stuff i
n
> the baggage compartment of my RV-6A.
>
>
> It was getting late and being a bit tired not to mention stressed, I need
ed
> to get a rental car and a motel for the night. Did that, eat dinner and
> went to bed after sitting down and drawing out a problem tree with the
> entire major elements of the electrical system.
>
>
> So next morning I show up at the hangar early and met Ben, the mechanic,
> the battery had received a charge of only 45 minutes the evening before,
So
> I suggested we charged it for another hour and try to start the aircraft.
> Ben suggested a real stress test of the battery and NOT charge it anymore
.
> Made sense, so we rolled the aircraft out of the hangar. I hopped in, th
rew
> a half dozen switches and punched the starter button. The engine started
on
> the first prop blade rotation ' so the battery was clearly OK. The engi
ne is
> humming like a top. So I looked over at the voltmeter expecting it to
> show only around 12.8 volts instead of the 14 volts a functioning alterna
tor
> would produce. Much to both my and Ben=92s surprise the alternator volt
age
> read 14 volts. We loaded the alternator by turning on the both l00 watt
> landing lights, all fuel pumps, the pitot heat, etc. The alternator volt
age
> only drops perhaps 0.4 volts clearly indicating the alternator could carr
y
> the load and was OK.
>
>
> So here I am ' battery is OK, alternator is OK ' engine is purring
> normally, so clearly this was all a figment of my deteriorating brain
> cells. I loaded up the aircraft and launched to do a few circuits of the
> airport ' I did so and all was operating normally and so I radio them I
was
> head onward to Texas. While flying (with my only functional eyeball on t
he
> voltmeter), my mind could not let go of the problem and finally the light
> bulb came on.
>
>
> The essential bus switch had (for my entire 10 + years of flying)always
> been in the alternator position. The purpose of this switch is, of cours
e,
> to isolate the battery from the alternator should the alternator fail -
to
> prevent an alternator problem from draining the battery. So in event of
an
> alternator problem, you move the switch from alternator to battery. Its
> call the essential bus because you only have the essential things drawing
> from the battery so you wont=92 drain it as quickly. The idea is to give
you
> time (generally around 30 minutes) to find a safe place to land in case o
f
> alternator failure.
>
>
> Well, at some point I had either (not paying attention) turned the switch
> to battery thinking I was turning the voltmeter switch to battery(more on
> that below) - or accidentally had move the switch from alternator to
> battery without noticing it by kicking it, etc. However, it was sort of
> protected in its position from accidental activation. It must have happen
ed
> during refueling ' as I got approx 45 minutes down the road on the batt
ery
> after take off before quality battery time started to deteriorate. As th
e
> battery voltage fell due to the load (and no alternator link to replenish
> it), electrical things (mainly computers first) started acting up until t
hey
> could not longer run the engine. The injectors would not open fully, etc.
> Then as the voltage level further decreased, the master relay which the
> battery held closed and which connected the (fully functional) alternator
to
> the rest of the electrical system - opened up and removed ALL power from
the
> electrical system. So no radio, no gauges, etc.
>
>
> Oh, another little factor that may have contributed, the voltmeter has a
> tiny toggle switch by it marked ALT BAT1 BAT2 for checking alternator
> battery 1 and battery 2 (which I no longer fly with) voltages. Down belo
w
> It a couple of inches and off to the right is the essential bus normal si
ze
> toggle switch ' also marked ALT BAT1 BAT1. I normally never touch it a
nd
> don=92t even think about it. But I could have reached for the voltmeter
> toggle thinking to check my battery voltage (which I do as a regular thin
g)
> and perhaps distracted by something reached a bit further down and instea
d
> moved the essential bus switch from Alternator to Battery causing this
> entire event. I know that I did not consciously do it. So it is either
> accidental or absence minded activation - either way ends with the same
> results {:>)
>
>
> Now it became clear why it didn=92t matter which pair of fuel injectors I
> turned off ' turning off either pair improved the situation because it
> slightly reduced the electrical load by a few amps ' and the engine ran
> slightly better for a few moments. The same thing had happened when turn
ing
> off one of the EFI fuel pumps ' but what threw me was the alternator vo
ltage
> continued to be normal during this.
>
>
> After I knew the cause (switch in wrong position), I decided the problem
> was fixed so no reason to return to NC, and I just continued on to Texas.
>
>
> I know some of you may think that removing my second battery was a mistak
e
> ' but, consider this, having another battery could have meant I would h
ave
> been much further from a suitable airfield before they both went south.
On
> the other hand, it might have caused me to at least think to throw the
> essential bus switch to the second battery and have the Light bulb come o
n.
> Who really knows. But, I have in mind a simply addition to my electrical
> circuit that should help in the future.
>
>
> I do want to state that this time when the problems started I DID switch
> fuel tanks ' but naturally it had no effect because this time it turned
out,
> it was not a fuel problem ' not the root cause at least.
>
>
> So what are the lessons learned:
>
>
> 1. Put EVERY critical switch on your before-takeoff Check list
> 2. Perhaps put a guard around such critical switches to force consciou
s
> activation
> 3. Don=92t (hard not to) get overly focused on what you think is the
> problem ' consider other possibilities. I thought it was a fuel pro
blem (I
> even switched fuel tanks this time) ' it turned out to be electrical
in its
> root cause.
> 4. While the fuel pressure was jumping all over the place and the EGT
> was erratic and engine surging strongly indicating a fuel problem '
the
> ultimate cause was electrical. Once the voltage got below a certain p
oint
> the EC2 computer was still trying to pull the injectors open, but wit
h the
> voltage so low it could not do it properly.
> 5. When the battery voltage dropped below a certain point, the master
> relay released and removed the alternator from the electrical system a
nd the
> panel went dark ' even though the alternator was still working
> 6. Immediately turn to the nearest airfield when serious problems occu
r
> - THEN work on fixing them. I only delayed for perhaps 2-3 minutes, b
ut
> that could have made a difference.
> 7. Watch out for *Coffin Corner* turn when turning base to final '
> airspeed really bleeds off fast with no engine pulling you along (and
> especially with flaps deployed!)
> 8. IF you change your mind about landing approach type - remember to
> reconfigure your aircraft for the last decision ' I had left my flap
s
> deployed when I should have remembered to retracted them. Did that he
lp
> prevent a Coffin Corner stall and spin or would it have put me closer
to it?
> 9. You must increase airspeed over the wing to get the sufficient
> energy to over come a high sink rate. Pulling back on the stick when
the
> ground is staring you in the face is the natural reaction ' but, pus
hing
> forward to lower the nose is the correct action ' providing of cours
e you
> have sufficient altitude!
> 10. Battery life ' I had a two year old 680 odyssey battery which I
> maintain a trickle charge on whenever I=92m not flying. With two EFI
fuel
> pumps, boost pump, injectors, coils, EC2 and radio and just having sta
rted
> the engine before take off ' this battery lasted 55 minutes. Well,
the last
> 5 minutes were not quality battery time. So in my case, 30 minutes ap
pears
> to be a very realistic battery life. In fact, had I turned off one EF
I pump
> and the boost pump would have gained a few more miles. But, if I had
> recognized the need to turn them off at that time (I normally turn the
m off
> at cruise altitude), then I would have known how to =93fix=94 the prob
lem.
> 11. I=92ve decided to add a Schokkty diode between my essential bus an
d
> the alternator ' so that as long as the alternator is producing suff
icient
> voltage, then the battery will be getting some charge to replace the d
rain.
> I=92ve also decided to make that switch position a check-list item.
>
>
> So what it boils down to ' if I had recognized early on that it was an
> electrical problem and not focused so much on the fuel system, I may have
> noticed the essential bus switch in the wrong position. Force yourself t
o
> examine other possible causes (easy to say ' harder to do).
>
>
> NEVER, NEVER forget that flying the airplane is the first and only priori
ty
> in this type of situation
>
>
> NEVER, NEVER forget that saving your butt is the ultimately end-all
> priority. When I decided that landing on the grass was preferable to
> putting a hole in their concrete ' I may have made a life-saving decis
ion.
>
>
> So that=92s my story and I=92m sticking to it.
>
>
> Fly safe, guys!!
>
>
> Ed
>
> Ed Anderson
>
> Rv-6A N494BW Rotary Powered
>
> Matthews, NC
>
> eanderson@carolina.rr.com
>
> http://www.andersonee.com
>
> http://www.dmack.net/mazda/index.html
>
> http://www.flyrotary.com/
>
> http://members.cox.net/rogersda/rotary/configs.htm#N494BW<http://members.
cox.net/rogersda/rotary/configs.htm>
>
> <http://www.dmack.net/mazda/index.html>
>
>
> *
>
===========
===========
===========
===========
> *
>
>
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Subject: | Re: Essential Incident - Almost (Long) |
Great writeup Ed. Thanks for sharing it with the list.
Regards,
Matt-
> It was suggested by one of the aeroelectric list members, Sam Hoskins,
> that
> the following report of an incident I had on a recent trip be posted to
> the
> AeroElectric list for obvious reasons - once you read it.
>
>
> I have an all-electric Rv-6A with over 10 years and close to 500 hours on
> it. I based the electrical system roughly one of Bob's excellent designs.
> It initially had one alternator and two batteries, but removed the second
> battery approx 5 years ago - but, I did make one modification to the
> design
> that I almost had cause to regret.
>
>
> So needless to say, but I will, responsibility for design and incident
> is
> totally mine.
>
>
> But, to get on with the tale
>
>
> One the way to Texas I had an incident that ended up in with me and
> aircraft
> making a 7 mile engine-out glide into Craig Field (Selma, Alabama). NO!
> It
> was not fault of the engine or even the subsystems. But, the complete
> answer is not provided until after my litany of the conditions and
> symptoms
> - can you figure it out?
>
>
> I took off on Thursday (28 May 2009) AM from North Carolina planning on
> stopping in Mississippi to join up with two friends. After spending the
> night there, we all three would then head for Texas. But, the weather (as
> you are aware) has been laying over the southeast for days with rain and
> more rain - but I launched into it anyway as past Atlanta, GA things were
> forecast to improve..
>
>
> Other than dodging lines of clouds and a bit of scud running, but not
> much,
> I landed at Alexandria City to the southwest of Atlanta, GA to take on
> fuel.
> I then climbed back in and fire it up and took off.
>
>
> I noticed that during climb-out the engine would occasionally miss and
> thought the fuel might have had a bit of water in it, but was not really
> concerned. So I fly on for approx another 45 minutes and had just passed
> Selma, Alabama and old Craig Air Force base, and turned west toward
> Mississippi, when more symptoms began to occur.
>
>
> It started to act like a case of SAG (fouled spark plugs) where the rpm
> will
> drop a bit - not dangerous - just nerve racking. But, shortly things
> began
> to go beyond the SAG symptoms, so I though I might have an injector
> problem
> (like one sticking open or not opening at all). Since our injectors are
> in
> pairs, I tried turning one pair off figuring if things got better, then
> that pair might have a bad injector.
>
>
> So I turned off one pair and sure enough the symptoms abated a bit (more
> on
> this later) so I figured I had a bad injector in that pair. To be certain
> I
> turned this "bad" pair back on and turn off the "good" pair expecting the
> symptoms to really get bad as I would now be running on only the "bad"
> pair
> - much to my surprise when I turned off the "good" pair - the symptoms
> also
> abated. So that indicated it was not an injector problem - but what?
>
>
> About this time, I decided to turn the aircraft back around toward Craig
> Field and dodging clouds headed back with the engine progressively getting
> worst. It appeared to be a fuel problem (and while that is ultimately the
> subsystem affected - it was not the root cause). The fuel pressure was
> ranging from zero to 80 psi, other electrical things were also
> misbehaving.
> I check the voltmeter thinking perhaps the alternator had died - but it
> showed 14 volts. So back to the fuel system.
>
>
> Finally, the engine just stops with the prop standing still - like a
> hood
> ornament, I'm at around 4500-5000 MSL at this point having lost some
> altitude dodging a cloud (good old GPS just kept pointing to Craig Field).
> At that time I am 6-7 miles out from Craig Field at 4500 msl with a
> stopped
> prop, a crippled seat cushion and a dry mouth. Yes, I've been there
> before,
> but I don't think you ever get "use" to it. I recalled thinking -".
> things
> just can't get worst." when they very shortly and suddenly - did.
>
>
> I keyed the radio and made a call to Craig Field at 4 miles on the GPS but
> before I could get their reply, I heard a "CLANK" (without the engine
> running you can hear things like that) like a relay springing open (it
> was)
> and the entire panel goes dead!!!! No radio, no engine instruments, not
> even a stinking LED was lit - only the battery powered GPS. Can you spell
> "total electrical failure?" Talk about a lonely feeling - amazing how
> comforting having lights on and radio - you could almost convince yourself
> this was just a practice engine-out landing, but not when the panel goes
> dark. No engine gauges, no radio, nada!
>
>
> Well not being one inclined to panic (but I seriously considered it for a
> moment {:>)), I continued toward Craig field - I mean like there were lots
> of other alternatives. Well Once again I found myself in the "fortunate
> position" of being too high, too much altitude. So I put in 40 degs of
> flaps
> to steepen my rate of descent. But, then I decided this time that rather
> than do the 360 I had done on a previous Incident to lose "excessive"
> altitude, I would try to glide - a more or less - regular traffic pattern.
>
>
> However, I neglected to remember to retract the flaps. So I found myself
> on
> the downwind around mid-field at pattern altitude (which felt normal)
> until
> I suddenly realized that you CAN NOT maintain that pattern altitude
> without
> an engine!!! (and particularly with 40 deg of flaps deployed - flaps and
> trim are manual) Duh!
>
>
> I knew I could never make it to the far end of the runway before turning
> base (toward the runway) and I was losing altitude at the rate of 400-500
> fpm, so I started my turn immediately. To make matters a bit worst - I
> had
> been paralleling the runway on the downwind leg a bit too close in - must
> have been the comforting feeling of being close to safety. This position
> naturally required a tighter turn and as I turned I saw I was likely to
> overshoot the runway and land in the grass. So I though I need to steepen
> this turn further (Yep! COFFIN CORNER was calling), but fortunately
> glanced
> at my airspeed indicator - to see it only registering 80 MPH and my rate
> of
> descent (normally 400-500 feet per minute) up to over 1000 feet per
> minute.
> The seat cushion suddenly vanished from this universe.
>
>
> But the REAL danger in this situation, as you all know, is your airspeed
> gets low, you are in a steep bank which greatly raises the stall speed -
> meaning at 80 mph you are close to a stall in a steep turn while your are
> not in straight and level. So I immediately straighten out of the turn -
> the little voice saying "better to land in the grass than get their
> concrete
> runway all messed up". So the immediate danger of a stall was adverted,
> but
> I was still pointed toward the ground with a sink rate twice as high as
> normal (and I've manage a few hard landings even with a normal sink rate).
> Fortunately, the runway was now under my nose rather than grass.
>
>
> The hardest thing to do when you are sinking at a 1000 fpm a couple
> hundred
> feet above the ground (with your nose already pointed at the ground) is to
> push the stick forward steeping the dive even more. But, I manage to do
> that and picked enough air speed and energy to flair to a nice touch down
> -
> not even a bump. I've always been amazed at what total concentration does
> to improve you landing {:>).
>
>
> Rolled to the end of the runway and had energy to roll off onto the
> taxiway.
> Got out, check under the aircraft for any evidence of leaks and started
> pulling the aircraft toward the far -off - hangar which had an airplane
> parked in front of it. A nice looking young woman comes riding a bicycle
> out to meet me. Hopped off and holding out her hand said "Hi I'm Angie,
> looks like we'll be spending time together" - so things were starting to
> look up {:>)
>
>
> So pulled the aircraft in to the hangar where the mechanic came over and
> ask
> what the problem was. Well, I looked at the volt meter and it said the
> battery was dead. Mechanic put on a battery charger and announced "Yep!
> The
> battery is dead". So we both concluded that the alternator must have
> failed
> and not being able to replenish the drain on the battery by all the
> electrical systems such as fuel pumps, injectors, ignition coils, etc had
> drained the battery.
>
>
> However, there were a few problems with the analysis of a failed
> alternator.
> First, the low voltage warning light never came on to warn of an
> alternator
> problem, 2nd I never notice the voltmeter showing anything other than what
> it should for alternator voltage - like around 14 volts. While checking
> the
> voltage after the Mechanic had charged the battery, I noticed down below
> that the "essential bus" switch was in the battery rather than the
> alternator position, so flicked it back to the alternator position
> figuring
> I must have accidentally kicked it while getting to some stuff in the
> baggage compartment of my RV-6A.
>
>
> It was getting late and being a bit tired not to mention stressed, I
> needed
> to get a rental car and a motel for the night. Did that, eat dinner and
> went to bed after sitting down and drawing out a problem tree with the
> entire major elements of the electrical system.
>
>
> So next morning I show up at the hangar early and met Ben, the mechanic,
> the
> battery had received a charge of only 45 minutes the evening before, So I
> suggested we charged it for another hour and try to start the aircraft.
> Ben
> suggested a real stress test of the battery and NOT charge it anymore.
> Made
> sense, so we rolled the aircraft out of the hangar. I hopped in, threw a
> half dozen switches and punched the starter button. The engine started on
> the first prop blade rotation - so the battery was clearly OK. The engine
> is
> humming like a top. So I looked over at the voltmeter expecting it to
> show only around 12.8 volts instead of the 14 volts a functioning
> alternator
> would produce. Much to both my and Ben's surprise the alternator voltage
> read 14 volts. We loaded the alternator by turning on the both l00 watt
> landing lights, all fuel pumps, the pitot heat, etc. The alternator
> voltage
> only drops perhaps 0.4 volts clearly indicating the alternator could carry
> the load and was OK.
>
>
> So here I am - battery is OK, alternator is OK - engine is purring
> normally,
> so clearly this was all a figment of my deteriorating brain cells. I
> loaded
> up the aircraft and launched to do a few circuits of the airport - I did
> so
> and all was operating normally and so I radio them I was head onward to
> Texas. While flying (with my only functional eyeball on the voltmeter),
> my
> mind could not let go of the problem and finally the light bulb came on.
>
>
> The essential bus switch had (for my entire 10 + years of flying)always
> been
> in the alternator position. The purpose of this switch is, of course, to
> isolate the battery from the alternator should the alternator fail - to
> prevent an alternator problem from draining the battery. So in event of
> an
> alternator problem, you move the switch from alternator to battery. Its
> call the essential bus because you only have the essential things drawing
> from the battery so you wont' drain it as quickly. The idea is to give
> you
> time (generally around 30 minutes) to find a safe place to land in case of
> alternator failure.
>
>
> Well, at some point I had either (not paying attention) turned the switch
> to
> battery thinking I was turning the voltmeter switch to battery(more on
> that
> below) - or accidentally had move the switch from alternator to battery
> without noticing it by kicking it, etc. However, it was sort of protected
> in its position from accidental activation. It must have happened during
> refueling - as I got approx 45 minutes down the road on the battery after
> take off before quality battery time started to deteriorate. As the
> battery
> voltage fell due to the load (and no alternator link to replenish it),
> electrical things (mainly computers first) started acting up until they
> could not longer run the engine. The injectors would not open fully, etc.
> Then as the voltage level further decreased, the master relay which the
> battery held closed and which connected the (fully functional) alternator
> to
> the rest of the electrical system - opened up and removed ALL power from
> the
> electrical system. So no radio, no gauges, etc.
>
>
> Oh, another little factor that may have contributed, the voltmeter has a
> tiny toggle switch by it marked ALT BAT1 BAT2 for checking alternator
> battery 1 and battery 2 (which I no longer fly with) voltages. Down below
> It a couple of inches and off to the right is the essential bus normal
> size
> toggle switch - also marked ALT BAT1 BAT1. I normally never touch it and
> don't even think about it. But I could have reached for the voltmeter
> toggle thinking to check my battery voltage (which I do as a regular
> thing)
> and perhaps distracted by something reached a bit further down and instead
> moved the essential bus switch from Alternator to Battery causing this
> entire event. I know that I did not consciously do it. So it is either
> accidental or absence minded activation - either way ends with the same
> results {:>)
>
>
> Now it became clear why it didn't matter which pair of fuel injectors I
> turned off - turning off either pair improved the situation because it
> slightly reduced the electrical load by a few amps - and the engine ran
> slightly better for a few moments. The same thing had happened when
> turning
> off one of the EFI fuel pumps - but what threw me was the alternator
> voltage
> continued to be normal during this.
>
>
> After I knew the cause (switch in wrong position), I decided the problem
> was
> fixed so no reason to return to NC, and I just continued on to Texas.
>
>
> I know some of you may think that removing my second battery was a mistake
> -
> but, consider this, having another battery could have meant I would have
> been much further from a suitable airfield before they both went south.
> On
> the other hand, it might have caused me to at least think to throw the
> essential bus switch to the second battery and have the Light bulb come
> on.
> Who really knows. But, I have in mind a simply addition to my electrical
> circuit that should help in the future.
>
>
> I do want to state that this time when the problems started I DID switch
> fuel tanks - but naturally it had no effect because this time it turned
> out,
> it was not a fuel problem - not the root cause at least.
>
>
> So what are the lessons learned:
>
>
> 1. Put EVERY critical switch on your before-takeoff Check list
> 2. Perhaps put a guard around such critical switches to force conscious
> activation
> 3. Don't (hard not to) get overly focused on what you think is the
> problem - consider other possibilities. I thought it was a fuel problem
> (I
> even switched fuel tanks this time) - it turned out to be electrical in
> its
> root cause.
> 4. While the fuel pressure was jumping all over the place and the EGT
> was erratic and engine surging strongly indicating a fuel problem - the
> ultimate cause was electrical. Once the voltage got below a certain point
> the EC2 computer was still trying to pull the injectors open, but with
> the
> voltage so low it could not do it properly.
> 5. When the battery voltage dropped below a certain point, the master
> relay released and removed the alternator from the electrical system and
> the
> panel went dark - even though the alternator was still working
> 6. Immediately turn to the nearest airfield when serious problems occur
> - THEN work on fixing them. I only delayed for perhaps 2-3 minutes, but
> that could have made a difference.
> 7. Watch out for Coffin Corner turn when turning base to final -
> airspeed really bleeds off fast with no engine pulling you along (and
> especially with flaps deployed!)
> 8. IF you change your mind about landing approach type - remember to
> reconfigure your aircraft for the last decision - I had left my flaps
> deployed when I should have remembered to retracted them. Did that help
> prevent a Coffin Corner stall and spin or would it have put me closer to
> it?
>
> 9. You must increase airspeed over the wing to get the sufficient
> energy to over come a high sink rate. Pulling back on the stick when the
> ground is staring you in the face is the natural reaction - but, pushing
> forward to lower the nose is the correct action - providing of course you
> have sufficient altitude!
> 10. Battery life - I had a two year old 680 odyssey battery which I
> maintain a trickle charge on whenever I'm not flying. With two EFI fuel
> pumps, boost pump, injectors, coils, EC2 and radio and just having started
> the engine before take off - this battery lasted 55 minutes. Well, the
> last
> 5 minutes were not quality battery time. So in my case, 30 minutes
> appears
> to be a very realistic battery life. In fact, had I turned off one EFI
> pump
> and the boost pump would have gained a few more miles. But, if I had
> recognized the need to turn them off at that time (I normally turn them
> off
> at cruise altitude), then I would have known how to "fix" the problem.
> 11. I've decided to add a Schokkty diode between my essential bus and
> the alternator - so that as long as the alternator is producing sufficient
> voltage, then the battery will be getting some charge to replace the
> drain.
> I've also decided to make that switch position a check-list item.
>
>
> So what it boils down to - if I had recognized early on that it was an
> electrical problem and not focused so much on the fuel system, I may have
> noticed the essential bus switch in the wrong position. Force yourself to
> examine other possible causes (easy to say - harder to do).
>
>
> NEVER, NEVER forget that flying the airplane is the first and only
> priority
> in this type of situation
>
>
> NEVER, NEVER forget that saving your butt is the ultimately end-all
> priority. When I decided that landing on the grass was preferable to
> putting a hole in their concrete - I may have made a life-saving
> decision.
>
>
> So that's my story and I'm sticking to it.
>
>
> Fly safe, guys!!
>
>
> Ed
>
> Ed Anderson
>
> Rv-6A N494BW Rotary Powered
>
> Matthews, NC
>
> eanderson@carolina.rr.com
>
> <http://www.andersonee.com> http://www.andersonee.com
>
> <http://www.dmack.net/mazda/index.html>
> http://www.dmack.net/mazda/index.html
>
> http://www.flyrotary.com/
>
> <http://members.cox.net/rogersda/rotary/configs.htm>
> http://members.cox.net/rogersda/rotary/configs.htm#N494BW
>
> <http://www.dmack.net/mazda/index.html>
>
>
Message 10
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Subject: | Re: Essential Incident - Almost (Long) |
Ed,
Congrats for keeping your cool, and flying the airplane to a safe
landing. And thanks for sharing the story, so we can all learn from
your incident.
I fully agree that checklists are important. If your electrical
system design assumes that the electrical system will be in a
particular configuration for flight, then you need a checklist that
ensures this is true. And you need to religiously do every step on
that checklist before take-off.
It is also useful to have well thought out checklists for engine
failure, engine rough running, etc. For example, a well thought rough
running engine checklist would include all steps necessary to check
voltage on whatever bus(s) your engine needs.
One thing that puzzles me about your electrical system design - it
seems that your engine needs power from the Essential Bus. But it
seems like your active low voltage warning is looking at some other
bus. Why not hook the low voltage warning up the the one bus that is
really important - i.e. the Essential Bus?
Kevin Horton
On 3-Jun-09, at 15:53 , Ed Anderson wrote:
> It was suggested by one of the aeroelectric list members, Sam
> Hoskins, that the following report of an incident I had on a recent
> trip be posted to the AeroElectric list for obvious reasons once
> you read it.
>
> I have an all-electric Rv-6A with over 10 years and close to 500
> hours on it. I based the electrical system roughly one of Bobs
> excellent designs. It initially had one alternator and two
> batteries, but removed the second battery approx 5 years ago but,
> I did make one modification to the design that I almost had cause
> to regret.
>
> So needless to say, but I will, responsibility for design and
> incident is totally mine.
>
> But, to get on with the tale
>
>
> One the way to Texas I had an incident that ended up in with me and
> aircraft making a 7 mile engine-out glide into Craig Field (Selma,
> Alabama). NO! It was not fault of the engine or even the
> subsystems. But, the complete answer is not provided until after my
> litany of the conditions and symptoms can you figure it out?
>
> I took off on Thursday (28 May 2009) AM from North Carolina planning
> on stopping in Mississippi to join up with two friends. After
> spending the night there, we all three would then head for Texas.
> But, the weather (as you are aware) has been laying over the
> southeast for days with rain and more rain but I launched into it
> anyway as past Atlanta, GA things were forecast to improve..
>
> Other than dodging lines of clouds and a bit of scud running, but
> not much, I landed at Alexandria City to the southwest of Atlanta,
> GA to take on fuel. I then climbed back in and fire it up and took
> off.
>
> I noticed that during climb-out the engine would occasionally miss
> and thought the fuel might have had a bit of water in it, but was
> not really concerned. So I fly on for approx another 45 minutes and
> had just passed Selma, Alabama and old Craig Air Force base, and
> turned west toward Mississippi, when more symptoms began to occur.
>
> It started to act like a case of SAG (fouled spark plugs) where the
> rpm will drop a bit not dangerous - just nerve racking. But,
> shortly things began to go beyond the SAG symptoms, so I though I
> might have an injector problem (like one sticking open or not
> opening at all). Since our injectors are in pairs, I tried turning
> one pair off figuring if things got better, then that pair might
> have a bad injector.
>
> So I turned off one pair and sure enough the symptoms abated a bit
> (more on this later) so I figured I had a bad injector in that
> pair. To be certain I turned this bad pair back on and turn off
> the good pair expecting the symptoms to really get bad as I would
> now be running on only the bad pair much to my surprise when I
> turned off the good pair the symptoms also abated. So that
> indicated it was not an injector problem but what?
>
> About this time, I decided to turn the aircraft back around toward
> Craig Field and dodging clouds headed back with the engine
> progressively getting worst. It appeared to be a fuel problem (and
> while that is ultimately the subsystem affected - it was not the
> root cause). The fuel pressure was ranging from zero to 80 psi,
> other electrical things were also misbehaving. I check the
> voltmeter thinking perhaps the alternator had died but it showed
> 14 volts. So back to the fuel system.
>
> Finally, the engine just stops with the prop standing still - like
> a hood ornament, Im at around 4500-5000 MSL at this point having
> lost some altitude dodging a cloud (good old GPS just kept pointing
> to Craig Field). At that time I am 6-7 miles out from Craig Field
> at 4500 msl with a stopped prop, a crippled seat cushion and a dry
> mouth. Yes, Ive been there before, but I dont think you ever get
> use to it. I recalled thinking things just cant get
> worst when they very shortly and suddenly - did.
>
> I keyed the radio and made a call to Craig Field at 4 miles on the
> GPS but before I could get their reply, I heard a CLANK (without
> the engine running you can hear things like that) like a relay
> springing open (it was) and the entire panel goes dead!!!! No
> radio, no engine instruments, not even a stinking LED was lit only
> the battery powered GPS. Can you spell total electrical failure?
> Talk about a lonely feeling amazing how comforting having lights
> on and radio you could almost convince yourself this was just a
> practice engine-out landing, but not when the panel goes dark. No
> engine gauges, no radio, nada!
>
> Well not being one inclined to panic (but I seriously considered it
> for a moment {:>)), I continued toward Craig field I mean like
> there were lots of other alternatives. Well Once again I found
> myself in the fortunate position of being too high, too much
> altitude. So I put in 40 degs of flaps to steepen my rate of
> descent. But, then I decided this time that rather than do the 360 I
> had done on a previous Incident to lose excessive altitude, I
> would try to glide - a more or less - regular traffic pattern.
>
> However, I neglected to remember to retract the flaps. So I found
> myself on the downwind around mid-field at pattern altitude (which
> felt normal) until I suddenly realized that you CAN NOT maintain
> that pattern altitude without an engine!!! (and particularly with
> 40 deg of flaps deployed flaps and trim are manual) Duh!
>
> I knew I could never make it to the far end of the runway before
> turning base (toward the runway) and I was losing altitude at the
> rate of 400-500 fpm, so I started my turn immediately. To make
> matters a bit worst - I had been paralleling the runway on the
> downwind leg a bit too close in must have been the comforting
> feeling of being close to safety. This position naturally required
> a tighter turn and as I turned I saw I was likely to overshoot the
> runway and land in the grass. So I though I need to steepen this
> turn further (Yep! COFFIN CORNER was calling), but fortunately
> glanced at my airspeed indicator - to see it only registering 80 MPH
> and my rate of descent (normally 400-500 feet per minute) up to over
> 1000 feet per minute. The seat cushion suddenly vanished from this
> universe.
>
> But the REAL danger in this situation, as you all know, is your
> airspeed gets low, you are in a steep bank which greatly raises the
> stall speed - meaning at 80 mph you are close to a stall in a steep
> turn while your are not in straight and level. So I immediately
> straighten out of the turn the little voice saying better to land
> in the grass than get their concrete runway all messed up. So the
> immediate danger of a stall was adverted, but I was still pointed
> toward the ground with a sink rate twice as high as normal (and Ive
> manage a few hard landings even with a normal sink rate).
> Fortunately, the runway was now under my nose rather than grass.
>
> The hardest thing to do when you are sinking at a 1000 fpm a couple
> hundred feet above the ground (with your nose already pointed at the
> ground) is to push the stick forward steeping the dive even more.
> But, I manage to do that and picked enough air speed and energy to
> flair to a nice touch down not even a bump. Ive always been
> amazed at what total concentration does to improve you landing {:>).
>
> Rolled to the end of the runway and had energy to roll off onto the
> taxiway. Got out, check under the aircraft for any evidence of
> leaks and started pulling the aircraft toward the far off hangar
> which had an airplane parked in front of it. A nice looking young
> woman comes riding a bicycle out to meet me. Hopped off and holding
> out her hand said Hi Im Angie, looks like well be spending time
> together so things were starting to look up {:>)
>
> So pulled the aircraft in to the hangar where the mechanic came over
> and ask what the problem was. Well, I looked at the volt meter and
> it said the battery was dead. Mechanic put on a battery charger and
> announced Yep! The battery is dead. So we both concluded that the
> alternator must have failed and not being able to replenish the
> drain on the battery by all the electrical systems such as fuel
> pumps, injectors, ignition coils, etc had drained the battery.
>
> However, there were a few problems with the analysis of a failed
> alternator. First, the low voltage warning light never came on to
> warn of an alternator problem, 2nd I never notice the voltmeter
> showing anything other than what it should for alternator voltage
> like around 14 volts. While checking the voltage after the Mechanic
> had charged the battery, I noticed down below that the essential
> bus switch was in the battery rather than the alternator position,
> so flicked it back to the alternator position figuring I must have
> accidentally kicked it while getting to some stuff in the baggage
> compartment of my RV-6A.
>
> It was getting late and being a bit tired not to mention stressed, I
> needed to get a rental car and a motel for the night. Did that, eat
> dinner and went to bed after sitting down and drawing out a problem
> tree with the entire major elements of the electrical system.
>
> So next morning I show up at the hangar early and met Ben, the
> mechanic, the battery had received a charge of only 45 minutes the
> evening before, So I suggested we charged it for another hour and
> try to start the aircraft. Ben suggested a real stress test of the
> battery and NOT charge it anymore. Made sense, so we rolled the
> aircraft out of the hangar. I hopped in, threw a half dozen
> switches and punched the starter button. The engine started on the
> first prop blade rotation so the battery was clearly OK. The
> engine is humming like a top. So I looked over at the voltmeter
> expecting it to show only around 12.8 volts instead of the 14 volts
> a functioning alternator would produce. Much to both my and Bens
> surprise the alternator voltage read 14 volts. We loaded the
> alternator by turning on the both l00 watt landing lights, all fuel
> pumps, the pitot heat, etc. The alternator voltage only drops
> perhaps 0.4 volts clearly indicating the alternator could carry the
> load and was OK.
>
> So here I am battery is OK, alternator is OK engine is purring
> normally, so clearly this was all a figment of my deteriorating
> brain cells. I loaded up the aircraft and launched to do a few
> circuits of the airport I did so and all was operating normally
> and so I radio them I was head onward to Texas. While flying (with
> my only functional eyeball on the voltmeter), my mind could not let
> go of the problem and finally the light bulb came on.
>
> The essential bus switch had (for my entire 10 + years of
> flying)always been in the alternator position. The purpose of this
> switch is, of course, to isolate the battery from the alternator
> should the alternator fail - to prevent an alternator problem from
> draining the battery. So in event of an alternator problem, you
> move the switch from alternator to battery. Its call the essential
> bus because you only have the essential things drawing from the
> battery so you wont drain it as quickly. The idea is to give you
> time (generally around 30 minutes) to find a safe place to land in
> case of alternator failure.
>
>
> Well, at some point I had either (not paying attention) turned the
> switch to battery thinking I was turning the voltmeter switch to
> battery(more on that below) - or accidentally had move the switch
> from alternator to battery without noticing it by kicking it, etc.
> However, it was sort of protected in its position from accidental
> activation. It must have happened during refueling as I got approx
> 45 minutes down the road on the battery after take off before
> quality battery time started to deteriorate. As the battery voltage
> fell due to the load (and no alternator link to replenish it),
> electrical things (mainly computers first) started acting up until
> they could not longer run the engine. The injectors would not open
> fully, etc. Then as the voltage level further decreased, the master
> relay which the battery held closed and which connected the (fully
> functional) alternator to the rest of the electrical system - opened
> up and removed ALL power from the electrical system. So no radio,
> no gauges, etc.
>
> Oh, another little factor that may have contributed, the voltmeter
> has a tiny toggle switch by it marked ALT BAT1 BAT2 for checking
> alternator battery 1 and battery 2 (which I no longer fly with)
> voltages. Down below It a couple of inches and off to the right is
> the essential bus normal size toggle switch also marked ALT BAT1
> BAT1. I normally never touch it and dont even think about it. But
> I could have reached for the voltmeter toggle thinking to check my
> battery voltage (which I do as a regular thing) and perhaps
> distracted by something reached a bit further down and instead moved
> the essential bus switch from Alternator to Battery causing this
> entire event. I know that I did not consciously do it. So it is
> either accidental or absence minded activation - either way ends
> with the same results {:>)
>
>
> Now it became clear why it didnt matter which pair of fuel
> injectors I turned off turning off either pair improved the
> situation because it slightly reduced the electrical load by a few
> amps and the engine ran slightly better for a few moments. The
> same thing had happened when turning off one of the EFI fuel pumps
> but what threw me was the alternator voltage continued to be normal
> during this.
>
> After I knew the cause (switch in wrong position), I decided the
> problem was fixed so no reason to return to NC, and I just continued
> on to Texas.
>
> I know some of you may think that removing my second battery was a
> mistake but, consider this, having another battery could have
> meant I would have been much further from a suitable airfield before
> they both went south. On the other hand, it might have caused me to
> at least think to throw the essential bus switch to the second
> battery and have the Light bulb come on. Who really knows. But, I
> have in mind a simply addition to my electrical circuit that should
> help in the future.
>
>
> I do want to state that this time when the problems started I DID
> switch fuel tanks but naturally it had no effect because this time
> it turned out, it was not a fuel problem not the root cause at
> least.
>
> So what are the lessons learned:
>
> Put EVERY critical switch on your before-takeoff Check list
> Perhaps put a guard around such critical switches to force
> conscious activation
> Dont (hard not to) get overly focused on what you think is the
> problem consider other possibilities. I thought it was a fuel
> problem (I even switched fuel tanks this time) it turned out to be
> electrical in its root cause.
> While the fuel pressure was jumping all over the place and the
> EGT was erratic and engine surging strongly indicating a fuel
> problem the ultimate cause was electrical. Once the voltage got
> below a certain point the EC2 computer was still trying to pull the
> injectors open, but with the voltage so low it could not do it
> properly.
> When the battery voltage dropped below a certain point, the
> master relay released and removed the alternator from the electrical
> system and the panel went dark even though the alternator was
> still working
> Immediately turn to the nearest airfield when serious problems
> occur - THEN work on fixing them. I only delayed for perhaps 2-3
> minutes, but that could have made a difference.
> Watch out for Coffin Corner turn when turning base to final
> airspeed really bleeds off fast with no engine pulling you along
> (and especially with flaps deployed!)
> IF you change your mind about landing approach type - remember to
> reconfigure your aircraft for the last decision I had left my
> flaps deployed when I should have remembered to retracted them. Did
> that help prevent a Coffin Corner stall and spin or would it have
> put me closer to it?
> You must increase airspeed over the wing to get the sufficient
> energy to over come a high sink rate. Pulling back on the stick
> when the ground is staring you in the face is the natural reaction
> but, pushing forward to lower the nose is the correct action
> providing of course you have sufficient altitude!
> Battery life I had a two year old 680 odyssey battery which I
> maintain a trickle charge on whenever Im not flying. With two EFI
> fuel pumps, boost pump, injectors, coils, EC2 and radio and just
> having started the engine before take off this battery lasted 55
> minutes. Well, the last 5 minutes were not quality battery time.
> So in my case, 30 minutes appears to be a very realistic battery
> life. In fact, had I turned off one EFI pump and the boost pump
> would have gained a few more miles. But, if I had recognized the
> need to turn them off at that time (I normally turn them off at
> cruise altitude), then I would have known how to fix the problem.
> Ive decided to add a Schokkty diode between my essential bus and
> the alternator so that as long as the alternator is producing
> sufficient voltage, then the battery will be getting some charge to
> replace the drain. Ive also decided to make that switch position a
> check-list item.
>
> So what it boils down to if I had recognized early on that it was
> an electrical problem and not focused so much on the fuel system, I
> may have noticed the essential bus switch in the wrong position.
> Force yourself to examine other possible causes (easy to say
> harder to do).
>
> NEVER, NEVER forget that flying the airplane is the first and only
> priority in this type of situation
>
> NEVER, NEVER forget that saving your butt is the ultimately end-all
> priority. When I decided that landing on the grass was preferable
> to putting a hole in their concrete I may have made a life-saving
> decision.
>
> So thats my story and Im sticking to it.
>
> Fly safe, guys!!
>
> Ed
> Ed Anderson
>
>
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Subject: | Essential Incident - Almost (Long) |
Sam, its just about on the centerline of the panel but down on the bottom.
So its actually outside my line of vision looking straight ahead. My
voltmeter and its toggle selector is above it approx 3-4" and slightly to
the left of it. Both are within reach without stretching.
As I mentioned the essential bus switch has been in the alternator position
for the past 10 years of flying and never moved since initial testing back
then. Should have had it on my pre-takeoff check list and will.
Ed
Ed Anderson
Rv-6A N494BW Rotary Powered
Matthews, NC
eanderson@carolina.rr.com
<http://www.andersonee.com> http://www.andersonee.com
<http://www.dmack.net/mazda/index.html>
http://www.dmack.net/mazda/index.html
http://www.flyrotary.com/
<http://members.cox.net/rogersda/rotary/configs.htm>
http://members.cox.net/rogersda/rotary/configs.htm#N494BW
http://www.rotaryaviation.com/Rotorhead%20Truth.htm
<http://www.dmack.net/mazda/index.html>
_____
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Sam
Hoskins
Sent: Wednesday, June 03, 2009 4:12 PM
Subject: Re: AeroElectric-List: Essential Incident - Almost (Long)
Ed - great story. Just out of curiosity, where is the essential bus switch
located? Is it plainly in your field of vision or do you have to turn your
head to see it?
Cockpit ergonomics are a huge challenge.
Sam Hoskins
www.samhoskins.blogspot.com
On Wed, Jun 3, 2009 at 2:53 PM, Ed Anderson <eanderson@carolina.rr.com>
wrote:
It was suggested by one of the aeroelectric list members, Sam Hoskins, that
the following report of an incident I had on a recent trip be posted to the
AeroElectric list for obvious reasons - once you read it.
I have an all-electric Rv-6A with over 10 years and close to 500 hours on
it. I based the electrical system roughly one of Bob's excellent designs.
It initially had one alternator and two batteries, but removed the second
battery approx 5 years ago - but, I did make one modification to the design
that I almost had cause to regret.
So needless to say, but I will, responsibility for design and incident is
totally mine.
But, to get on with the tale
One the way to Texas I had an incident that ended up in with me and aircraft
making a 7 mile engine-out glide into Craig Field (Selma, Alabama). NO! It
was not fault of the engine or even the subsystems. But, the complete
answer is not provided until after my litany of the conditions and symptoms
- can you figure it out?
I took off on Thursday (28 May 2009) AM from North Carolina planning on
stopping in Mississippi to join up with two friends. After spending the
night there, we all three would then head for Texas. But, the weather (as
you are aware) has been laying over the southeast for days with rain and
more rain - but I launched into it anyway as past Atlanta, GA things were
forecast to improve..
Other than dodging lines of clouds and a bit of scud running, but not much,
I landed at Alexandria City to the southwest of Atlanta, GA to take on fuel.
I then climbed back in and fire it up and took off.
I noticed that during climb-out the engine would occasionally miss and
thought the fuel might have had a bit of water in it, but was not really
concerned. So I fly on for approx another 45 minutes and had just passed
Selma, Alabama and old Craig Air Force base, and turned west toward
Mississippi, when more symptoms began to occur.
It started to act like a case of SAG (fouled spark plugs) where the rpm will
drop a bit - not dangerous - just nerve racking. But, shortly things began
to go beyond the SAG symptoms, so I though I might have an injector problem
(like one sticking open or not opening at all). Since our injectors are in
pairs, I tried turning one pair off figuring if things got better, then
that pair might have a bad injector.
So I turned off one pair and sure enough the symptoms abated a bit (more on
this later) so I figured I had a bad injector in that pair. To be certain I
turned this "bad" pair back on and turn off the "good" pair expecting the
symptoms to really get bad as I would now be running on only the "bad" pair
- much to my surprise when I turned off the "good" pair - the symptoms also
abated. So that indicated it was not an injector problem - but what?
About this time, I decided to turn the aircraft back around toward Craig
Field and dodging clouds headed back with the engine progressively getting
worst. It appeared to be a fuel problem (and while that is ultimately the
subsystem affected - it was not the root cause). The fuel pressure was
ranging from zero to 80 psi, other electrical things were also misbehaving.
I check the voltmeter thinking perhaps the alternator had died - but it
showed 14 volts. So back to the fuel system.
Finally, the engine just stops with the prop standing still - like a hood
ornament, I'm at around 4500-5000 MSL at this point having lost some
altitude dodging a cloud (good old GPS just kept pointing to Craig Field).
At that time I am 6-7 miles out from Craig Field at 4500 msl with a stopped
prop, a crippled seat cushion and a dry mouth. Yes, I've been there before,
but I don't think you ever get "use" to it. I recalled thinking -". things
just can't get worst." when they very shortly and suddenly - did.
I keyed the radio and made a call to Craig Field at 4 miles on the GPS but
before I could get their reply, I heard a "CLANK" (without the engine
running you can hear things like that) like a relay springing open (it was)
and the entire panel goes dead!!!! No radio, no engine instruments, not
even a stinking LED was lit - only the battery powered GPS. Can you spell
"total electrical failure?" Talk about a lonely feeling - amazing how
comforting having lights on and radio - you could almost convince yourself
this was just a practice engine-out landing, but not when the panel goes
dark. No engine gauges, no radio, nada!
Well not being one inclined to panic (but I seriously considered it for a
moment {:>)), I continued toward Craig field - I mean like there were lots
of other alternatives. Well Once again I found myself in the "fortunate
position" of being too high, too much altitude. So I put in 40 degs of flaps
to steepen my rate of descent. But, then I decided this time that rather
than do the 360 I had done on a previous Incident to lose "excessive"
altitude, I would try to glide - a more or less - regular traffic pattern.
However, I neglected to remember to retract the flaps. So I found myself on
the downwind around mid-field at pattern altitude (which felt normal) until
I suddenly realized that you CAN NOT maintain that pattern altitude without
an engine!!! (and particularly with 40 deg of flaps deployed - flaps and
trim are manual) Duh!
I knew I could never make it to the far end of the runway before turning
base (toward the runway) and I was losing altitude at the rate of 400-500
fpm, so I started my turn immediately. To make matters a bit worst - I had
been paralleling the runway on the downwind leg a bit too close in - must
have been the comforting feeling of being close to safety. This position
naturally required a tighter turn and as I turned I saw I was likely to
overshoot the runway and land in the grass. So I though I need to steepen
this turn further (Yep! COFFIN CORNER was calling), but fortunately glanced
at my airspeed indicator - to see it only registering 80 MPH and my rate of
descent (normally 400-500 feet per minute) up to over 1000 feet per minute.
The seat cushion suddenly vanished from this universe.
But the REAL danger in this situation, as you all know, is your airspeed
gets low, you are in a steep bank which greatly raises the stall speed -
meaning at 80 mph you are close to a stall in a steep turn while your are
not in straight and level. So I immediately straighten out of the turn -
the little voice saying "better to land in the grass than get their concrete
runway all messed up". So the immediate danger of a stall was adverted, but
I was still pointed toward the ground with a sink rate twice as high as
normal (and I've manage a few hard landings even with a normal sink rate).
Fortunately, the runway was now under my nose rather than grass.
The hardest thing to do when you are sinking at a 1000 fpm a couple hundred
feet above the ground (with your nose already pointed at the ground) is to
push the stick forward steeping the dive even more. But, I manage to do
that and picked enough air speed and energy to flair to a nice touch down -
not even a bump. I've always been amazed at what total concentration does
to improve you landing {:>).
Rolled to the end of the runway and had energy to roll off onto the taxiway.
Got out, check under the aircraft for any evidence of leaks and started
pulling the aircraft toward the far -off - hangar which had an airplane
parked in front of it. A nice looking young woman comes riding a bicycle
out to meet me. Hopped off and holding out her hand said "Hi I'm Angie,
looks like we'll be spending time together" - so things were starting to
look up {:>)
So pulled the aircraft in to the hangar where the mechanic came over and ask
what the problem was. Well, I looked at the volt meter and it said the
battery was dead. Mechanic put on a battery charger and announced "Yep! The
battery is dead". So we both concluded that the alternator must have failed
and not being able to replenish the drain on the battery by all the
electrical systems such as fuel pumps, injectors, ignition coils, etc had
drained the battery.
However, there were a few problems with the analysis of a failed alternator.
First, the low voltage warning light never came on to warn of an alternator
problem, 2nd I never notice the voltmeter showing anything other than what
it should for alternator voltage - like around 14 volts. While checking the
voltage after the Mechanic had charged the battery, I noticed down below
that the "essential bus" switch was in the battery rather than the
alternator position, so flicked it back to the alternator position figuring
I must have accidentally kicked it while getting to some stuff in the
baggage compartment of my RV-6A.
It was getting late and being a bit tired not to mention stressed, I needed
to get a rental car and a motel for the night. Did that, eat dinner and
went to bed after sitting down and drawing out a problem tree with the
entire major elements of the electrical system.
So next morning I show up at the hangar early and met Ben, the mechanic, the
battery had received a charge of only 45 minutes the evening before, So I
suggested we charged it for another hour and try to start the aircraft. Ben
suggested a real stress test of the battery and NOT charge it anymore. Made
sense, so we rolled the aircraft out of the hangar. I hopped in, threw a
half dozen switches and punched the starter button. The engine started on
the first prop blade rotation - so the battery was clearly OK. The engine is
humming like a top. So I looked over at the voltmeter expecting it to
show only around 12.8 volts instead of the 14 volts a functioning alternator
would produce. Much to both my and Ben's surprise the alternator voltage
read 14 volts. We loaded the alternator by turning on the both l00 watt
landing lights, all fuel pumps, the pitot heat, etc. The alternator voltage
only drops perhaps 0.4 volts clearly indicating the alternator could carry
the load and was OK.
So here I am - battery is OK, alternator is OK - engine is purring normally,
so clearly this was all a figment of my deteriorating brain cells. I loaded
up the aircraft and launched to do a few circuits of the airport - I did so
and all was operating normally and so I radio them I was head onward to
Texas. While flying (with my only functional eyeball on the voltmeter), my
mind could not let go of the problem and finally the light bulb came on.
The essential bus switch had (for my entire 10 + years of flying)always been
in the alternator position. The purpose of this switch is, of course, to
isolate the battery from the alternator should the alternator fail - to
prevent an alternator problem from draining the battery. So in event of an
alternator problem, you move the switch from alternator to battery. Its
call the essential bus because you only have the essential things drawing
from the battery so you wont' drain it as quickly. The idea is to give you
time (generally around 30 minutes) to find a safe place to land in case of
alternator failure.
Well, at some point I had either (not paying attention) turned the switch to
battery thinking I was turning the voltmeter switch to battery(more on that
below) - or accidentally had move the switch from alternator to battery
without noticing it by kicking it, etc. However, it was sort of protected
in its position from accidental activation. It must have happened during
refueling - as I got approx 45 minutes down the road on the battery after
take off before quality battery time started to deteriorate. As the battery
voltage fell due to the load (and no alternator link to replenish it),
electrical things (mainly computers first) started acting up until they
could not longer run the engine. The injectors would not open fully, etc.
Then as the voltage level further decreased, the master relay which the
battery held closed and which connected the (fully functional) alternator to
the rest of the electrical system - opened up and removed ALL power from the
electrical system. So no radio, no gauges, etc.
Oh, another little factor that may have contributed, the voltmeter has a
tiny toggle switch by it marked ALT BAT1 BAT2 for checking alternator
battery 1 and battery 2 (which I no longer fly with) voltages. Down below
It a couple of inches and off to the right is the essential bus normal size
toggle switch - also marked ALT BAT1 BAT1. I normally never touch it and
don't even think about it. But I could have reached for the voltmeter
toggle thinking to check my battery voltage (which I do as a regular thing)
and perhaps distracted by something reached a bit further down and instead
moved the essential bus switch from Alternator to Battery causing this
entire event. I know that I did not consciously do it. So it is either
accidental or absence minded activation - either way ends with the same
results {:>)
Now it became clear why it didn't matter which pair of fuel injectors I
turned off - turning off either pair improved the situation because it
slightly reduced the electrical load by a few amps - and the engine ran
slightly better for a few moments. The same thing had happened when turning
off one of the EFI fuel pumps - but what threw me was the alternator voltage
continued to be normal during this.
After I knew the cause (switch in wrong position), I decided the problem was
fixed so no reason to return to NC, and I just continued on to Texas.
I know some of you may think that removing my second battery was a mistake -
but, consider this, having another battery could have meant I would have
been much further from a suitable airfield before they both went south. On
the other hand, it might have caused me to at least think to throw the
essential bus switch to the second battery and have the Light bulb come on.
Who really knows. But, I have in mind a simply addition to my electrical
circuit that should help in the future.
I do want to state that this time when the problems started I DID switch
fuel tanks - but naturally it had no effect because this time it turned out,
it was not a fuel problem - not the root cause at least.
So what are the lessons learned:
1. Put EVERY critical switch on your before-takeoff Check list
2. Perhaps put a guard around such critical switches to force conscious
activation
3. Don't (hard not to) get overly focused on what you think is the
problem - consider other possibilities. I thought it was a fuel problem (I
even switched fuel tanks this time) - it turned out to be electrical in its
root cause.
4. While the fuel pressure was jumping all over the place and the EGT
was erratic and engine surging strongly indicating a fuel problem - the
ultimate cause was electrical. Once the voltage got below a certain point
the EC2 computer was still trying to pull the injectors open, but with the
voltage so low it could not do it properly.
5. When the battery voltage dropped below a certain point, the master
relay released and removed the alternator from the electrical system and the
panel went dark - even though the alternator was still working
6. Immediately turn to the nearest airfield when serious problems occur
- THEN work on fixing them. I only delayed for perhaps 2-3 minutes, but
that could have made a difference.
7. Watch out for Coffin Corner turn when turning base to final -
airspeed really bleeds off fast with no engine pulling you along (and
especially with flaps deployed!)
8. IF you change your mind about landing approach type - remember to
reconfigure your aircraft for the last decision - I had left my flaps
deployed when I should have remembered to retracted them. Did that help
prevent a Coffin Corner stall and spin or would it have put me closer to it?
9. You must increase airspeed over the wing to get the sufficient
energy to over come a high sink rate. Pulling back on the stick when the
ground is staring you in the face is the natural reaction - but, pushing
forward to lower the nose is the correct action - providing of course you
have sufficient altitude!
10. Battery life - I had a two year old 680 odyssey battery which I
maintain a trickle charge on whenever I'm not flying. With two EFI fuel
pumps, boost pump, injectors, coils, EC2 and radio and just having started
the engine before take off - this battery lasted 55 minutes. Well, the last
5 minutes were not quality battery time. So in my case, 30 minutes appears
to be a very realistic battery life. In fact, had I turned off one EFI pump
and the boost pump would have gained a few more miles. But, if I had
recognized the need to turn them off at that time (I normally turn them off
at cruise altitude), then I would have known how to "fix" the problem.
11. I've decided to add a Schokkty diode between my essential bus and
the alternator - so that as long as the alternator is producing sufficient
voltage, then the battery will be getting some charge to replace the drain.
I've also decided to make that switch position a check-list item.
So what it boils down to - if I had recognized early on that it was an
electrical problem and not focused so much on the fuel system, I may have
noticed the essential bus switch in the wrong position. Force yourself to
examine other possible causes (easy to say - harder to do).
NEVER, NEVER forget that flying the airplane is the first and only priority
in this type of situation
NEVER, NEVER forget that saving your butt is the ultimately end-all
priority. When I decided that landing on the grass was preferable to
putting a hole in their concrete - I may have made a life-saving decision.
So that's my story and I'm sticking to it.
Fly safe, guys!!
Ed
Ed Anderson
Rv-6A N494BW Rotary Powered
Matthews, NC
eanderson@carolina.rr.com
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Subject: | Essential Incident - Almost (Long) |
Thanks, Matt
Ed Anderson
Rv-6A N494BW Rotary Powered
Matthews, NC
eanderson@carolina.rr.com
http://www.andersonee.com
http://www.dmack.net/mazda/index.html
http://www.flyrotary.com/
http://members.cox.net/rogersda/rotary/configs.htm#N494BW
http://www.rotaryaviation.com/Rotorhead%20Truth.htm
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Matt
Prather
Sent: Wednesday, June 03, 2009 4:40 PM
Subject: Re: AeroElectric-List: Essential Incident - Almost (Long)
Great writeup Ed. Thanks for sharing it with the list.
Regards,
Matt-
> It was suggested by one of the aeroelectric list members, Sam Hoskins,
> that
> the following report of an incident I had on a recent trip be posted to
> the
> AeroElectric list for obvious reasons - once you read it.
>
>
> I have an all-electric Rv-6A with over 10 years and close to 500 hours on
> it. I based the electrical system roughly one of Bob's excellent designs.
> It initially had one alternator and two batteries, but removed the second
> battery approx 5 years ago - but, I did make one modification to the
> design
> that I almost had cause to regret.
>
>
> So needless to say, but I will, responsibility for design and incident
> is
> totally mine.
>
>
> But, to get on with the tale
>
>
> One the way to Texas I had an incident that ended up in with me and
> aircraft
> making a 7 mile engine-out glide into Craig Field (Selma, Alabama). NO!
> It
> was not fault of the engine or even the subsystems. But, the complete
> answer is not provided until after my litany of the conditions and
> symptoms
> - can you figure it out?
>
>
> I took off on Thursday (28 May 2009) AM from North Carolina planning on
> stopping in Mississippi to join up with two friends. After spending the
> night there, we all three would then head for Texas. But, the weather (as
> you are aware) has been laying over the southeast for days with rain and
> more rain - but I launched into it anyway as past Atlanta, GA things were
> forecast to improve..
>
>
> Other than dodging lines of clouds and a bit of scud running, but not
> much,
> I landed at Alexandria City to the southwest of Atlanta, GA to take on
> fuel.
> I then climbed back in and fire it up and took off.
>
>
> I noticed that during climb-out the engine would occasionally miss and
> thought the fuel might have had a bit of water in it, but was not really
> concerned. So I fly on for approx another 45 minutes and had just passed
> Selma, Alabama and old Craig Air Force base, and turned west toward
> Mississippi, when more symptoms began to occur.
>
>
> It started to act like a case of SAG (fouled spark plugs) where the rpm
> will
> drop a bit - not dangerous - just nerve racking. But, shortly things
> began
> to go beyond the SAG symptoms, so I though I might have an injector
> problem
> (like one sticking open or not opening at all). Since our injectors are
> in
> pairs, I tried turning one pair off figuring if things got better, then
> that pair might have a bad injector.
>
>
> So I turned off one pair and sure enough the symptoms abated a bit (more
> on
> this later) so I figured I had a bad injector in that pair. To be certain
> I
> turned this "bad" pair back on and turn off the "good" pair expecting the
> symptoms to really get bad as I would now be running on only the "bad"
> pair
> - much to my surprise when I turned off the "good" pair - the symptoms
> also
> abated. So that indicated it was not an injector problem - but what?
>
>
> About this time, I decided to turn the aircraft back around toward Craig
> Field and dodging clouds headed back with the engine progressively getting
> worst. It appeared to be a fuel problem (and while that is ultimately the
> subsystem affected - it was not the root cause). The fuel pressure was
> ranging from zero to 80 psi, other electrical things were also
> misbehaving.
> I check the voltmeter thinking perhaps the alternator had died - but it
> showed 14 volts. So back to the fuel system.
>
>
> Finally, the engine just stops with the prop standing still - like a
> hood
> ornament, I'm at around 4500-5000 MSL at this point having lost some
> altitude dodging a cloud (good old GPS just kept pointing to Craig Field).
> At that time I am 6-7 miles out from Craig Field at 4500 msl with a
> stopped
> prop, a crippled seat cushion and a dry mouth. Yes, I've been there
> before,
> but I don't think you ever get "use" to it. I recalled thinking -".
> things
> just can't get worst." when they very shortly and suddenly - did.
>
>
> I keyed the radio and made a call to Craig Field at 4 miles on the GPS but
> before I could get their reply, I heard a "CLANK" (without the engine
> running you can hear things like that) like a relay springing open (it
> was)
> and the entire panel goes dead!!!! No radio, no engine instruments, not
> even a stinking LED was lit - only the battery powered GPS. Can you spell
> "total electrical failure?" Talk about a lonely feeling - amazing how
> comforting having lights on and radio - you could almost convince yourself
> this was just a practice engine-out landing, but not when the panel goes
> dark. No engine gauges, no radio, nada!
>
>
> Well not being one inclined to panic (but I seriously considered it for a
> moment {:>)), I continued toward Craig field - I mean like there were lots
> of other alternatives. Well Once again I found myself in the "fortunate
> position" of being too high, too much altitude. So I put in 40 degs of
> flaps
> to steepen my rate of descent. But, then I decided this time that rather
> than do the 360 I had done on a previous Incident to lose "excessive"
> altitude, I would try to glide - a more or less - regular traffic pattern.
>
>
> However, I neglected to remember to retract the flaps. So I found myself
> on
> the downwind around mid-field at pattern altitude (which felt normal)
> until
> I suddenly realized that you CAN NOT maintain that pattern altitude
> without
> an engine!!! (and particularly with 40 deg of flaps deployed - flaps and
> trim are manual) Duh!
>
>
> I knew I could never make it to the far end of the runway before turning
> base (toward the runway) and I was losing altitude at the rate of 400-500
> fpm, so I started my turn immediately. To make matters a bit worst - I
> had
> been paralleling the runway on the downwind leg a bit too close in - must
> have been the comforting feeling of being close to safety. This position
> naturally required a tighter turn and as I turned I saw I was likely to
> overshoot the runway and land in the grass. So I though I need to steepen
> this turn further (Yep! COFFIN CORNER was calling), but fortunately
> glanced
> at my airspeed indicator - to see it only registering 80 MPH and my rate
> of
> descent (normally 400-500 feet per minute) up to over 1000 feet per
> minute.
> The seat cushion suddenly vanished from this universe.
>
>
> But the REAL danger in this situation, as you all know, is your airspeed
> gets low, you are in a steep bank which greatly raises the stall speed -
> meaning at 80 mph you are close to a stall in a steep turn while your are
> not in straight and level. So I immediately straighten out of the turn -
> the little voice saying "better to land in the grass than get their
> concrete
> runway all messed up". So the immediate danger of a stall was adverted,
> but
> I was still pointed toward the ground with a sink rate twice as high as
> normal (and I've manage a few hard landings even with a normal sink rate).
> Fortunately, the runway was now under my nose rather than grass.
>
>
> The hardest thing to do when you are sinking at a 1000 fpm a couple
> hundred
> feet above the ground (with your nose already pointed at the ground) is to
> push the stick forward steeping the dive even more. But, I manage to do
> that and picked enough air speed and energy to flair to a nice touch down
> -
> not even a bump. I've always been amazed at what total concentration does
> to improve you landing {:>).
>
>
> Rolled to the end of the runway and had energy to roll off onto the
> taxiway.
> Got out, check under the aircraft for any evidence of leaks and started
> pulling the aircraft toward the far -off - hangar which had an airplane
> parked in front of it. A nice looking young woman comes riding a bicycle
> out to meet me. Hopped off and holding out her hand said "Hi I'm Angie,
> looks like we'll be spending time together" - so things were starting to
> look up {:>)
>
>
> So pulled the aircraft in to the hangar where the mechanic came over and
> ask
> what the problem was. Well, I looked at the volt meter and it said the
> battery was dead. Mechanic put on a battery charger and announced "Yep!
> The
> battery is dead". So we both concluded that the alternator must have
> failed
> and not being able to replenish the drain on the battery by all the
> electrical systems such as fuel pumps, injectors, ignition coils, etc had
> drained the battery.
>
>
> However, there were a few problems with the analysis of a failed
> alternator.
> First, the low voltage warning light never came on to warn of an
> alternator
> problem, 2nd I never notice the voltmeter showing anything other than what
> it should for alternator voltage - like around 14 volts. While checking
> the
> voltage after the Mechanic had charged the battery, I noticed down below
> that the "essential bus" switch was in the battery rather than the
> alternator position, so flicked it back to the alternator position
> figuring
> I must have accidentally kicked it while getting to some stuff in the
> baggage compartment of my RV-6A.
>
>
> It was getting late and being a bit tired not to mention stressed, I
> needed
> to get a rental car and a motel for the night. Did that, eat dinner and
> went to bed after sitting down and drawing out a problem tree with the
> entire major elements of the electrical system.
>
>
> So next morning I show up at the hangar early and met Ben, the mechanic,
> the
> battery had received a charge of only 45 minutes the evening before, So I
> suggested we charged it for another hour and try to start the aircraft.
> Ben
> suggested a real stress test of the battery and NOT charge it anymore.
> Made
> sense, so we rolled the aircraft out of the hangar. I hopped in, threw a
> half dozen switches and punched the starter button. The engine started on
> the first prop blade rotation - so the battery was clearly OK. The engine
> is
> humming like a top. So I looked over at the voltmeter expecting it to
> show only around 12.8 volts instead of the 14 volts a functioning
> alternator
> would produce. Much to both my and Ben's surprise the alternator voltage
> read 14 volts. We loaded the alternator by turning on the both l00 watt
> landing lights, all fuel pumps, the pitot heat, etc. The alternator
> voltage
> only drops perhaps 0.4 volts clearly indicating the alternator could carry
> the load and was OK.
>
>
> So here I am - battery is OK, alternator is OK - engine is purring
> normally,
> so clearly this was all a figment of my deteriorating brain cells. I
> loaded
> up the aircraft and launched to do a few circuits of the airport - I did
> so
> and all was operating normally and so I radio them I was head onward to
> Texas. While flying (with my only functional eyeball on the voltmeter),
> my
> mind could not let go of the problem and finally the light bulb came on.
>
>
> The essential bus switch had (for my entire 10 + years of flying)always
> been
> in the alternator position. The purpose of this switch is, of course, to
> isolate the battery from the alternator should the alternator fail - to
> prevent an alternator problem from draining the battery. So in event of
> an
> alternator problem, you move the switch from alternator to battery. Its
> call the essential bus because you only have the essential things drawing
> from the battery so you wont' drain it as quickly. The idea is to give
> you
> time (generally around 30 minutes) to find a safe place to land in case of
> alternator failure.
>
>
> Well, at some point I had either (not paying attention) turned the switch
> to
> battery thinking I was turning the voltmeter switch to battery(more on
> that
> below) - or accidentally had move the switch from alternator to battery
> without noticing it by kicking it, etc. However, it was sort of protected
> in its position from accidental activation. It must have happened during
> refueling - as I got approx 45 minutes down the road on the battery after
> take off before quality battery time started to deteriorate. As the
> battery
> voltage fell due to the load (and no alternator link to replenish it),
> electrical things (mainly computers first) started acting up until they
> could not longer run the engine. The injectors would not open fully, etc.
> Then as the voltage level further decreased, the master relay which the
> battery held closed and which connected the (fully functional) alternator
> to
> the rest of the electrical system - opened up and removed ALL power from
> the
> electrical system. So no radio, no gauges, etc.
>
>
> Oh, another little factor that may have contributed, the voltmeter has a
> tiny toggle switch by it marked ALT BAT1 BAT2 for checking alternator
> battery 1 and battery 2 (which I no longer fly with) voltages. Down below
> It a couple of inches and off to the right is the essential bus normal
> size
> toggle switch - also marked ALT BAT1 BAT1. I normally never touch it and
> don't even think about it. But I could have reached for the voltmeter
> toggle thinking to check my battery voltage (which I do as a regular
> thing)
> and perhaps distracted by something reached a bit further down and instead
> moved the essential bus switch from Alternator to Battery causing this
> entire event. I know that I did not consciously do it. So it is either
> accidental or absence minded activation - either way ends with the same
> results {:>)
>
>
> Now it became clear why it didn't matter which pair of fuel injectors I
> turned off - turning off either pair improved the situation because it
> slightly reduced the electrical load by a few amps - and the engine ran
> slightly better for a few moments. The same thing had happened when
> turning
> off one of the EFI fuel pumps - but what threw me was the alternator
> voltage
> continued to be normal during this.
>
>
> After I knew the cause (switch in wrong position), I decided the problem
> was
> fixed so no reason to return to NC, and I just continued on to Texas.
>
>
> I know some of you may think that removing my second battery was a mistake
> -
> but, consider this, having another battery could have meant I would have
> been much further from a suitable airfield before they both went south.
> On
> the other hand, it might have caused me to at least think to throw the
> essential bus switch to the second battery and have the Light bulb come
> on.
> Who really knows. But, I have in mind a simply addition to my electrical
> circuit that should help in the future.
>
>
> I do want to state that this time when the problems started I DID switch
> fuel tanks - but naturally it had no effect because this time it turned
> out,
> it was not a fuel problem - not the root cause at least.
>
>
> So what are the lessons learned:
>
>
> 1. Put EVERY critical switch on your before-takeoff Check list
> 2. Perhaps put a guard around such critical switches to force conscious
> activation
> 3. Don't (hard not to) get overly focused on what you think is the
> problem - consider other possibilities. I thought it was a fuel problem
> (I
> even switched fuel tanks this time) - it turned out to be electrical in
> its
> root cause.
> 4. While the fuel pressure was jumping all over the place and the EGT
> was erratic and engine surging strongly indicating a fuel problem - the
> ultimate cause was electrical. Once the voltage got below a certain point
> the EC2 computer was still trying to pull the injectors open, but with
> the
> voltage so low it could not do it properly.
> 5. When the battery voltage dropped below a certain point, the master
> relay released and removed the alternator from the electrical system and
> the
> panel went dark - even though the alternator was still working
> 6. Immediately turn to the nearest airfield when serious problems occur
> - THEN work on fixing them. I only delayed for perhaps 2-3 minutes, but
> that could have made a difference.
> 7. Watch out for Coffin Corner turn when turning base to final -
> airspeed really bleeds off fast with no engine pulling you along (and
> especially with flaps deployed!)
> 8. IF you change your mind about landing approach type - remember to
> reconfigure your aircraft for the last decision - I had left my flaps
> deployed when I should have remembered to retracted them. Did that help
> prevent a Coffin Corner stall and spin or would it have put me closer to
> it?
>
> 9. You must increase airspeed over the wing to get the sufficient
> energy to over come a high sink rate. Pulling back on the stick when the
> ground is staring you in the face is the natural reaction - but, pushing
> forward to lower the nose is the correct action - providing of course you
> have sufficient altitude!
> 10. Battery life - I had a two year old 680 odyssey battery which I
> maintain a trickle charge on whenever I'm not flying. With two EFI fuel
> pumps, boost pump, injectors, coils, EC2 and radio and just having started
> the engine before take off - this battery lasted 55 minutes. Well, the
> last
> 5 minutes were not quality battery time. So in my case, 30 minutes
> appears
> to be a very realistic battery life. In fact, had I turned off one EFI
> pump
> and the boost pump would have gained a few more miles. But, if I had
> recognized the need to turn them off at that time (I normally turn them
> off
> at cruise altitude), then I would have known how to "fix" the problem.
> 11. I've decided to add a Schokkty diode between my essential bus and
> the alternator - so that as long as the alternator is producing sufficient
> voltage, then the battery will be getting some charge to replace the
> drain.
> I've also decided to make that switch position a check-list item.
>
>
> So what it boils down to - if I had recognized early on that it was an
> electrical problem and not focused so much on the fuel system, I may have
> noticed the essential bus switch in the wrong position. Force yourself to
> examine other possible causes (easy to say - harder to do).
>
>
> NEVER, NEVER forget that flying the airplane is the first and only
> priority
> in this type of situation
>
>
> NEVER, NEVER forget that saving your butt is the ultimately end-all
> priority. When I decided that landing on the grass was preferable to
> putting a hole in their concrete - I may have made a life-saving
> decision.
>
>
> So that's my story and I'm sticking to it.
>
>
> Fly safe, guys!!
>
>
> Ed
>
> Ed Anderson
>
> Rv-6A N494BW Rotary Powered
>
> Matthews, NC
>
> eanderson@carolina.rr.com
>
> <http://www.andersonee.com> http://www.andersonee.com
>
> <http://www.dmack.net/mazda/index.html>
> http://www.dmack.net/mazda/index.html
>
> http://www.flyrotary.com/
>
> <http://members.cox.net/rogersda/rotary/configs.htm>
> http://members.cox.net/rogersda/rotary/configs.htm#N494BW
>
> <http://www.dmack.net/mazda/index.html>
>
>
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Subject: | Essential Incident - Almost (Long) |
Thanks Kevin
Could not agree with your points more. Yes, I have a pre-takeoff check list
which I do use - however, as you point out - if an item is not on it that is
critical to safe flight, then it is certainly incomplete.
I do not have an in-flight emergency check list, but will certainly give
that some serious thought - it would be helpful if it just isolated whether
the problem was the fuel system, electrical system and their subsystems.
Another good suggestion
Ah, good analysis, Kevin. You are correct, my low voltage light is hooked to
my alternator circuit and not the essential bus. The logic (if there was
any) was that if the alternator started to fail then the warning light would
warn me before I started to drain the battery. However, in this case, the
alternator was continuing to produce 14 V so naturally the low voltage light
never came on. So again, I agree on all the points you made.
Just goes to show you how even things designed to make it safer can do the
opposite under certain conditions. Clearly, there are a few things that I
need to change {:>)
Ed
Ed Anderson
Rv-6A N494BW Rotary Powered
Matthews, NC
eanderson@carolina.rr.com
http://www.andersonee.com
http://www.dmack.net/mazda/index.html
http://www.flyrotary.com/
http://members.cox.net/rogersda/rotary/configs.htm#N494BW
http://www.rotaryaviation.com/Rotorhead%20Truth.htm
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Kevin
Horton
Sent: Wednesday, June 03, 2009 5:02 PM
Subject: Re: AeroElectric-List: Essential Incident - Almost (Long)
Ed,
Congrats for keeping your cool, and flying the airplane to a safe
landing. And thanks for sharing the story, so we can all learn from
your incident.
I fully agree that checklists are important. If your electrical
system design assumes that the electrical system will be in a
particular configuration for flight, then you need a checklist that
ensures this is true. And you need to religiously do every step on
that checklist before take-off.
It is also useful to have well thought out checklists for engine
failure, engine rough running, etc. For example, a well thought rough
running engine checklist would include all steps necessary to check
voltage on whatever bus(s) your engine needs.
One thing that puzzles me about your electrical system design - it
seems that your engine needs power from the Essential Bus. But it
seems like your active low voltage warning is looking at some other
bus. Why not hook the low voltage warning up the the one bus that is
really important - i.e. the Essential Bus?
Kevin Horton
On 3-Jun-09, at 15:53 , Ed Anderson wrote:
> It was suggested by one of the aeroelectric list members, Sam
> Hoskins, that the following report of an incident I had on a recent
> trip be posted to the AeroElectric list for obvious reasons - once
> you read it.
>
> I have an all-electric Rv-6A with over 10 years and close to 500
> hours on it. I based the electrical system roughly one of Bob's
> excellent designs. It initially had one alternator and two
> batteries, but removed the second battery approx 5 years ago - but,
> I did make one modification to the design that I almost had cause
> to regret.
>
> So needless to say, but I will, responsibility for design and
> incident is totally mine.
>
> But, to get on with the tale
>
>
> One the way to Texas I had an incident that ended up in with me and
> aircraft making a 7 mile engine-out glide into Craig Field (Selma,
> Alabama). NO! It was not fault of the engine or even the
> subsystems. But, the complete answer is not provided until after my
> litany of the conditions and symptoms - can you figure it out?
>
> I took off on Thursday (28 May 2009) AM from North Carolina planning
> on stopping in Mississippi to join up with two friends. After
> spending the night there, we all three would then head for Texas.
> But, the weather (as you are aware) has been laying over the
> southeast for days with rain and more rain - but I launched into it
> anyway as past Atlanta, GA things were forecast to improve..
>
> Other than dodging lines of clouds and a bit of scud running, but
> not much, I landed at Alexandria City to the southwest of Atlanta,
> GA to take on fuel. I then climbed back in and fire it up and took
> off.
>
> I noticed that during climb-out the engine would occasionally miss
> and thought the fuel might have had a bit of water in it, but was
> not really concerned. So I fly on for approx another 45 minutes and
> had just passed Selma, Alabama and old Craig Air Force base, and
> turned west toward Mississippi, when more symptoms began to occur.
>
> It started to act like a case of SAG (fouled spark plugs) where the
> rpm will drop a bit - not dangerous - just nerve racking. But,
> shortly things began to go beyond the SAG symptoms, so I though I
> might have an injector problem (like one sticking open or not
> opening at all). Since our injectors are in pairs, I tried turning
> one pair off figuring if things got better, then that pair might
> have a bad injector.
>
> So I turned off one pair and sure enough the symptoms abated a bit
> (more on this later) so I figured I had a bad injector in that
> pair. To be certain I turned this "bad" pair back on and turn off
> the "good" pair expecting the symptoms to really get bad as I would
> now be running on only the "bad" pair - much to my surprise when I
> turned off the "good" pair - the symptoms also abated. So that
> indicated it was not an injector problem - but what?
>
> About this time, I decided to turn the aircraft back around toward
> Craig Field and dodging clouds headed back with the engine
> progressively getting worst. It appeared to be a fuel problem (and
> while that is ultimately the subsystem affected - it was not the
> root cause). The fuel pressure was ranging from zero to 80 psi,
> other electrical things were also misbehaving. I check the
> voltmeter thinking perhaps the alternator had died - but it showed
> 14 volts. So back to the fuel system.
>
> Finally, the engine just stops with the prop standing still - like
> a hood ornament, I'm at around 4500-5000 MSL at this point having
> lost some altitude dodging a cloud (good old GPS just kept pointing
> to Craig Field). At that time I am 6-7 miles out from Craig Field
> at 4500 msl with a stopped prop, a crippled seat cushion and a dry
> mouth. Yes, I've been there before, but I don't think you ever get
> "use" to it. I recalled thinking -". things just can't get
> worst." when they very shortly and suddenly - did.
>
> I keyed the radio and made a call to Craig Field at 4 miles on the
> GPS but before I could get their reply, I heard a "CLANK" (without
> the engine running you can hear things like that) like a relay
> springing open (it was) and the entire panel goes dead!!!! No
> radio, no engine instruments, not even a stinking LED was lit - only
> the battery powered GPS. Can you spell "total electrical failure?"
> Talk about a lonely feeling - amazing how comforting having lights
> on and radio - you could almost convince yourself this was just a
> practice engine-out landing, but not when the panel goes dark. No
> engine gauges, no radio, nada!
>
> Well not being one inclined to panic (but I seriously considered it
> for a moment {:>)), I continued toward Craig field - I mean like
> there were lots of other alternatives. Well Once again I found
> myself in the "fortunate position" of being too high, too much
> altitude. So I put in 40 degs of flaps to steepen my rate of
> descent. But, then I decided this time that rather than do the 360 I
> had done on a previous Incident to lose "excessive" altitude, I
> would try to glide - a more or less - regular traffic pattern.
>
> However, I neglected to remember to retract the flaps. So I found
> myself on the downwind around mid-field at pattern altitude (which
> felt normal) until I suddenly realized that you CAN NOT maintain
> that pattern altitude without an engine!!! (and particularly with
> 40 deg of flaps deployed - flaps and trim are manual) Duh!
>
> I knew I could never make it to the far end of the runway before
> turning base (toward the runway) and I was losing altitude at the
> rate of 400-500 fpm, so I started my turn immediately. To make
> matters a bit worst - I had been paralleling the runway on the
> downwind leg a bit too close in - must have been the comforting
> feeling of being close to safety. This position naturally required
> a tighter turn and as I turned I saw I was likely to overshoot the
> runway and land in the grass. So I though I need to steepen this
> turn further (Yep! COFFIN CORNER was calling), but fortunately
> glanced at my airspeed indicator - to see it only registering 80 MPH
> and my rate of descent (normally 400-500 feet per minute) up to over
> 1000 feet per minute. The seat cushion suddenly vanished from this
> universe.
>
> But the REAL danger in this situation, as you all know, is your
> airspeed gets low, you are in a steep bank which greatly raises the
> stall speed - meaning at 80 mph you are close to a stall in a steep
> turn while your are not in straight and level. So I immediately
> straighten out of the turn - the little voice saying "better to land
> in the grass than get their concrete runway all messed up". So the
> immediate danger of a stall was adverted, but I was still pointed
> toward the ground with a sink rate twice as high as normal (and I've
> manage a few hard landings even with a normal sink rate).
> Fortunately, the runway was now under my nose rather than grass.
>
> The hardest thing to do when you are sinking at a 1000 fpm a couple
> hundred feet above the ground (with your nose already pointed at the
> ground) is to push the stick forward steeping the dive even more.
> But, I manage to do that and picked enough air speed and energy to
> flair to a nice touch down - not even a bump. I've always been
> amazed at what total concentration does to improve you landing {:>).
>
> Rolled to the end of the runway and had energy to roll off onto the
> taxiway. Got out, check under the aircraft for any evidence of
> leaks and started pulling the aircraft toward the far -off - hangar
> which had an airplane parked in front of it. A nice looking young
> woman comes riding a bicycle out to meet me. Hopped off and holding
> out her hand said "Hi I'm Angie, looks like we'll be spending time
> together" - so things were starting to look up {:>)
>
> So pulled the aircraft in to the hangar where the mechanic came over
> and ask what the problem was. Well, I looked at the volt meter and
> it said the battery was dead. Mechanic put on a battery charger and
> announced "Yep! The battery is dead". So we both concluded that the
> alternator must have failed and not being able to replenish the
> drain on the battery by all the electrical systems such as fuel
> pumps, injectors, ignition coils, etc had drained the battery.
>
> However, there were a few problems with the analysis of a failed
> alternator. First, the low voltage warning light never came on to
> warn of an alternator problem, 2nd I never notice the voltmeter
> showing anything other than what it should for alternator voltage -
> like around 14 volts. While checking the voltage after the Mechanic
> had charged the battery, I noticed down below that the "essential
> bus" switch was in the battery rather than the alternator position,
> so flicked it back to the alternator position figuring I must have
> accidentally kicked it while getting to some stuff in the baggage
> compartment of my RV-6A.
>
> It was getting late and being a bit tired not to mention stressed, I
> needed to get a rental car and a motel for the night. Did that, eat
> dinner and went to bed after sitting down and drawing out a problem
> tree with the entire major elements of the electrical system.
>
> So next morning I show up at the hangar early and met Ben, the
> mechanic, the battery had received a charge of only 45 minutes the
> evening before, So I suggested we charged it for another hour and
> try to start the aircraft. Ben suggested a real stress test of the
> battery and NOT charge it anymore. Made sense, so we rolled the
> aircraft out of the hangar. I hopped in, threw a half dozen
> switches and punched the starter button. The engine started on the
> first prop blade rotation - so the battery was clearly OK. The
> engine is humming like a top. So I looked over at the voltmeter
> expecting it to show only around 12.8 volts instead of the 14 volts
> a functioning alternator would produce. Much to both my and Ben's
> surprise the alternator voltage read 14 volts. We loaded the
> alternator by turning on the both l00 watt landing lights, all fuel
> pumps, the pitot heat, etc. The alternator voltage only drops
> perhaps 0.4 volts clearly indicating the alternator could carry the
> load and was OK.
>
> So here I am - battery is OK, alternator is OK - engine is purring
> normally, so clearly this was all a figment of my deteriorating
> brain cells. I loaded up the aircraft and launched to do a few
> circuits of the airport - I did so and all was operating normally
> and so I radio them I was head onward to Texas. While flying (with
> my only functional eyeball on the voltmeter), my mind could not let
> go of the problem and finally the light bulb came on.
>
> The essential bus switch had (for my entire 10 + years of
> flying)always been in the alternator position. The purpose of this
> switch is, of course, to isolate the battery from the alternator
> should the alternator fail - to prevent an alternator problem from
> draining the battery. So in event of an alternator problem, you
> move the switch from alternator to battery. Its call the essential
> bus because you only have the essential things drawing from the
> battery so you wont' drain it as quickly. The idea is to give you
> time (generally around 30 minutes) to find a safe place to land in
> case of alternator failure.
>
>
> Well, at some point I had either (not paying attention) turned the
> switch to battery thinking I was turning the voltmeter switch to
> battery(more on that below) - or accidentally had move the switch
> from alternator to battery without noticing it by kicking it, etc.
> However, it was sort of protected in its position from accidental
> activation. It must have happened during refueling - as I got approx
> 45 minutes down the road on the battery after take off before
> quality battery time started to deteriorate. As the battery voltage
> fell due to the load (and no alternator link to replenish it),
> electrical things (mainly computers first) started acting up until
> they could not longer run the engine. The injectors would not open
> fully, etc. Then as the voltage level further decreased, the master
> relay which the battery held closed and which connected the (fully
> functional) alternator to the rest of the electrical system - opened
> up and removed ALL power from the electrical system. So no radio,
> no gauges, etc.
>
> Oh, another little factor that may have contributed, the voltmeter
> has a tiny toggle switch by it marked ALT BAT1 BAT2 for checking
> alternator battery 1 and battery 2 (which I no longer fly with)
> voltages. Down below It a couple of inches and off to the right is
> the essential bus normal size toggle switch - also marked ALT BAT1
> BAT1. I normally never touch it and don't even think about it. But
> I could have reached for the voltmeter toggle thinking to check my
> battery voltage (which I do as a regular thing) and perhaps
> distracted by something reached a bit further down and instead moved
> the essential bus switch from Alternator to Battery causing this
> entire event. I know that I did not consciously do it. So it is
> either accidental or absence minded activation - either way ends
> with the same results {:>)
>
>
> Now it became clear why it didn't matter which pair of fuel
> injectors I turned off - turning off either pair improved the
> situation because it slightly reduced the electrical load by a few
> amps - and the engine ran slightly better for a few moments. The
> same thing had happened when turning off one of the EFI fuel pumps -
> but what threw me was the alternator voltage continued to be normal
> during this.
>
> After I knew the cause (switch in wrong position), I decided the
> problem was fixed so no reason to return to NC, and I just continued
> on to Texas.
>
> I know some of you may think that removing my second battery was a
> mistake - but, consider this, having another battery could have
> meant I would have been much further from a suitable airfield before
> they both went south. On the other hand, it might have caused me to
> at least think to throw the essential bus switch to the second
> battery and have the Light bulb come on. Who really knows. But, I
> have in mind a simply addition to my electrical circuit that should
> help in the future.
>
>
> I do want to state that this time when the problems started I DID
> switch fuel tanks - but naturally it had no effect because this time
> it turned out, it was not a fuel problem - not the root cause at
> least.
>
> So what are the lessons learned:
>
> . Put EVERY critical switch on your before-takeoff Check list
> . Perhaps put a guard around such critical switches to force
> conscious activation
> . Don't (hard not to) get overly focused on what you think is the
> problem - consider other possibilities. I thought it was a fuel
> problem (I even switched fuel tanks this time) - it turned out to be
> electrical in its root cause.
> . While the fuel pressure was jumping all over the place and the
> EGT was erratic and engine surging strongly indicating a fuel
> problem - the ultimate cause was electrical. Once the voltage got
> below a certain point the EC2 computer was still trying to pull the
> injectors open, but with the voltage so low it could not do it
> properly.
> . When the battery voltage dropped below a certain point, the
> master relay released and removed the alternator from the electrical
> system and the panel went dark - even though the alternator was
> still working
> . Immediately turn to the nearest airfield when serious problems
> occur - THEN work on fixing them. I only delayed for perhaps 2-3
> minutes, but that could have made a difference.
> . Watch out for Coffin Corner turn when turning base to final -
> airspeed really bleeds off fast with no engine pulling you along
> (and especially with flaps deployed!)
> . IF you change your mind about landing approach type - remember to
> reconfigure your aircraft for the last decision - I had left my
> flaps deployed when I should have remembered to retracted them. Did
> that help prevent a Coffin Corner stall and spin or would it have
> put me closer to it?
> . You must increase airspeed over the wing to get the sufficient
> energy to over come a high sink rate. Pulling back on the stick
> when the ground is staring you in the face is the natural reaction -
> but, pushing forward to lower the nose is the correct action -
> providing of course you have sufficient altitude!
> . Battery life - I had a two year old 680 odyssey battery which I
> maintain a trickle charge on whenever I'm not flying. With two EFI
> fuel pumps, boost pump, injectors, coils, EC2 and radio and just
> having started the engine before take off - this battery lasted 55
> minutes. Well, the last 5 minutes were not quality battery time.
> So in my case, 30 minutes appears to be a very realistic battery
> life. In fact, had I turned off one EFI pump and the boost pump
> would have gained a few more miles. But, if I had recognized the
> need to turn them off at that time (I normally turn them off at
> cruise altitude), then I would have known how to "fix" the problem.
> . I've decided to add a Schokkty diode between my essential bus and
> the alternator - so that as long as the alternator is producing
> sufficient voltage, then the battery will be getting some charge to
> replace the drain. I've also decided to make that switch position a
> check-list item.
>
> So what it boils down to - if I had recognized early on that it was
> an electrical problem and not focused so much on the fuel system, I
> may have noticed the essential bus switch in the wrong position.
> Force yourself to examine other possible causes (easy to say -
> harder to do).
>
> NEVER, NEVER forget that flying the airplane is the first and only
> priority in this type of situation
>
> NEVER, NEVER forget that saving your butt is the ultimately end-all
> priority. When I decided that landing on the grass was preferable
> to putting a hole in their concrete - I may have made a life-saving
> decision.
>
> So that's my story and I'm sticking to it.
>
> Fly safe, guys!!
>
> Ed
> Ed Anderson
>
>
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Subject: | Essential Incident - Almost (Long) |
Ed, just curious,... How is it that your essential switch disconnects the
main bus? Usually, they power the essential bus but you have to shut off
the Main bus (I think) manually as a safety feature. When you heard the
CLANK which you said was the main bus relay disconnecting, that would have
been caused by the absolute drain of the battery. BUT, with the master
relay still engaged, the alternator should have still been charging the
battery? (even with the E-Bus switch thrown,... I think?
If your essential completely reroutes the current from the alternator around
the battery, then what takes up the load with the single battery off line?
Is that what the second battery (removed) was supposed to do?
Just wondering how it works?
Thanks Bill S
7a finishing / Z13/8 and other stuff
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Ed
Anderson
Sent: Wednesday, June 03, 2009 7:51 PM
Subject: RE: AeroElectric-List: Essential Incident - Almost (Long)
--> <eanderson@carolina.rr.com>
Thanks Kevin
Could not agree with your points more. Yes, I have a pre-takeoff check list
which I do use - however, as you point out - if an item is not on it that is
critical to safe flight, then it is certainly incomplete.
I do not have an in-flight emergency check list, but will certainly give
that some serious thought - it would be helpful if it just isolated whether
the problem was the fuel system, electrical system and their subsystems.
Another good suggestion
Ah, good analysis, Kevin. You are correct, my low voltage light is hooked to
my alternator circuit and not the essential bus. The logic (if there was
any) was that if the alternator started to fail then the warning light would
warn me before I started to drain the battery. However, in this case, the
alternator was continuing to produce 14 V so naturally the low voltage light
never came on. So again, I agree on all the points you made.
Just goes to show you how even things designed to make it safer can do the
opposite under certain conditions. Clearly, there are a few things that I
need to change {:>)
Ed
Ed Anderson
Rv-6A N494BW Rotary Powered
Matthews, NC
eanderson@carolina.rr.com
http://www.andersonee.com
http://www.dmack.net/mazda/index.html
http://www.flyrotary.com/
http://members.cox.net/rogersda/rotary/configs.htm#N494BW
http://www.rotaryaviation.com/Rotorhead%20Truth.htm
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Kevin
Horton
Sent: Wednesday, June 03, 2009 5:02 PM
Subject: Re: AeroElectric-List: Essential Incident - Almost (Long)
--> <khorton01@rogers.com>
Ed,
Congrats for keeping your cool, and flying the airplane to a safe landing.
And thanks for sharing the story, so we can all learn from your incident.
I fully agree that checklists are important. If your electrical system
design assumes that the electrical system will be in a particular
configuration for flight, then you need a checklist that ensures this is
true. And you need to religiously do every step on that checklist before
take-off.
It is also useful to have well thought out checklists for engine failure,
engine rough running, etc. For example, a well thought rough running engine
checklist would include all steps necessary to check voltage on whatever
bus(s) your engine needs.
One thing that puzzles me about your electrical system design - it seems
that your engine needs power from the Essential Bus. But it seems like your
active low voltage warning is looking at some other bus. Why not hook the
low voltage warning up the the one bus that is really important - i.e. the
Essential Bus?
Kevin Horton
On 3-Jun-09, at 15:53 , Ed Anderson wrote:
> It was suggested by one of the aeroelectric list members, Sam Hoskins,
> that the following report of an incident I had on a recent trip be
> posted to the AeroElectric list for obvious reasons - once you read
> it.
>
> I have an all-electric Rv-6A with over 10 years and close to 500
> hours on it. I based the electrical system roughly one of Bob's
> excellent designs. It initially had one alternator and two
> batteries, but removed the second battery approx 5 years ago - but, I
> did make one modification to the design that I almost had cause to
> regret.
>
> So needless to say, but I will, responsibility for design and
> incident is totally mine.
>
> But, to get on with the tale
>
>
> One the way to Texas I had an incident that ended up in with me and
> aircraft making a 7 mile engine-out glide into Craig Field (Selma,
> Alabama). NO! It was not fault of the engine or even the subsystems.
> But, the complete answer is not provided until after my litany of the
> conditions and symptoms - can you figure it out?
>
> I took off on Thursday (28 May 2009) AM from North Carolina planning
> on stopping in Mississippi to join up with two friends. After
> spending the night there, we all three would then head for Texas.
> But, the weather (as you are aware) has been laying over the southeast
> for days with rain and more rain - but I launched into it anyway as
> past Atlanta, GA things were forecast to improve..
>
> Other than dodging lines of clouds and a bit of scud running, but not
> much, I landed at Alexandria City to the southwest of Atlanta, GA to
> take on fuel. I then climbed back in and fire it up and took off.
>
> I noticed that during climb-out the engine would occasionally miss and
> thought the fuel might have had a bit of water in it, but was not
> really concerned. So I fly on for approx another 45 minutes and had
> just passed Selma, Alabama and old Craig Air Force base, and turned
> west toward Mississippi, when more symptoms began to occur.
>
> It started to act like a case of SAG (fouled spark plugs) where the
> rpm will drop a bit - not dangerous - just nerve racking. But,
> shortly things began to go beyond the SAG symptoms, so I though I
> might have an injector problem (like one sticking open or not opening
> at all). Since our injectors are in pairs, I tried turning one pair
> off figuring if things got better, then that pair might have a bad
> injector.
>
> So I turned off one pair and sure enough the symptoms abated a bit
> (more on this later) so I figured I had a bad injector in that pair.
> To be certain I turned this "bad" pair back on and turn off the "good"
> pair expecting the symptoms to really get bad as I would now be
> running on only the "bad" pair - much to my surprise when I turned off
> the "good" pair - the symptoms also abated. So that indicated it was
> not an injector problem - but what?
>
> About this time, I decided to turn the aircraft back around toward
> Craig Field and dodging clouds headed back with the engine
> progressively getting worst. It appeared to be a fuel problem (and
> while that is ultimately the subsystem affected - it was not the root
> cause). The fuel pressure was ranging from zero to 80 psi, other
> electrical things were also misbehaving. I check the voltmeter
> thinking perhaps the alternator had died - but it showed
> 14 volts. So back to the fuel system.
>
> Finally, the engine just stops with the prop standing still - like a
> hood ornament, I'm at around 4500-5000 MSL at this point having lost
> some altitude dodging a cloud (good old GPS just kept pointing to
> Craig Field). At that time I am 6-7 miles out from Craig Field at
> 4500 msl with a stopped prop, a crippled seat cushion and a dry mouth.
> Yes, I've been there before, but I don't think you ever get "use" to
> it. I recalled thinking -". things just can't get
> worst." when they very shortly and suddenly - did.
>
> I keyed the radio and made a call to Craig Field at 4 miles on the GPS
> but before I could get their reply, I heard a "CLANK" (without the
> engine running you can hear things like that) like a relay
> springing open (it was) and the entire panel goes dead!!!! No
> radio, no engine instruments, not even a stinking LED was lit - only
> the battery powered GPS. Can you spell "total electrical failure?"
> Talk about a lonely feeling - amazing how comforting having lights on
> and radio - you could almost convince yourself this was just a
> practice engine-out landing, but not when the panel goes dark. No
> engine gauges, no radio, nada!
>
> Well not being one inclined to panic (but I seriously considered it
> for a moment {:>)), I continued toward Craig field - I mean like there
> were lots of other alternatives. Well Once again I found myself in
> the "fortunate position" of being too high, too much altitude. So I
> put in 40 degs of flaps to steepen my rate of descent. But, then I
> decided this time that rather than do the 360 I had done on a previous
> Incident to lose "excessive" altitude, I would try to glide - a more
> or less - regular traffic pattern.
>
> However, I neglected to remember to retract the flaps. So I found
> myself on the downwind around mid-field at pattern altitude (which
> felt normal) until I suddenly realized that you CAN NOT maintain that
> pattern altitude without an engine!!! (and particularly with 40 deg
> of flaps deployed - flaps and trim are manual) Duh!
>
> I knew I could never make it to the far end of the runway before
> turning base (toward the runway) and I was losing altitude at the
> rate of 400-500 fpm, so I started my turn immediately. To make
> matters a bit worst - I had been paralleling the runway on the
> downwind leg a bit too close in - must have been the comforting
> feeling of being close to safety. This position naturally required a
> tighter turn and as I turned I saw I was likely to overshoot the
> runway and land in the grass. So I though I need to steepen this turn
> further (Yep! COFFIN CORNER was calling), but fortunately glanced at
> my airspeed indicator - to see it only registering 80 MPH and my rate
> of descent (normally 400-500 feet per minute) up to over 1000 feet per
> minute. The seat cushion suddenly vanished from this universe.
>
> But the REAL danger in this situation, as you all know, is your
> airspeed gets low, you are in a steep bank which greatly raises the
> stall speed - meaning at 80 mph you are close to a stall in a steep
> turn while your are not in straight and level. So I immediately
> straighten out of the turn - the little voice saying "better to land
> in the grass than get their concrete runway all messed up". So the
> immediate danger of a stall was adverted, but I was still pointed
> toward the ground with a sink rate twice as high as normal (and I've
> manage a few hard landings even with a normal sink rate).
> Fortunately, the runway was now under my nose rather than grass.
>
> The hardest thing to do when you are sinking at a 1000 fpm a couple
> hundred feet above the ground (with your nose already pointed at the
> ground) is to push the stick forward steeping the dive even more.
> But, I manage to do that and picked enough air speed and energy to
> flair to a nice touch down - not even a bump. I've always been amazed
> at what total concentration does to improve you landing {:>).
>
> Rolled to the end of the runway and had energy to roll off onto the
> taxiway. Got out, check under the aircraft for any evidence of
> leaks and started pulling the aircraft toward the far -off - hangar
> which had an airplane parked in front of it. A nice looking young
> woman comes riding a bicycle out to meet me. Hopped off and holding
> out her hand said "Hi I'm Angie, looks like we'll be spending time
> together" - so things were starting to look up {:>)
>
> So pulled the aircraft in to the hangar where the mechanic came over
> and ask what the problem was. Well, I looked at the volt meter and it
> said the battery was dead. Mechanic put on a battery charger and
> announced "Yep! The battery is dead". So we both concluded that the
> alternator must have failed and not being able to replenish the drain
> on the battery by all the electrical systems such as fuel pumps,
> injectors, ignition coils, etc had drained the battery.
>
> However, there were a few problems with the analysis of a failed
> alternator. First, the low voltage warning light never came on to
> warn of an alternator problem, 2nd I never notice the voltmeter
> showing anything other than what it should for alternator voltage -
> like around 14 volts. While checking the voltage after the Mechanic
> had charged the battery, I noticed down below that the "essential bus"
> switch was in the battery rather than the alternator position, so
> flicked it back to the alternator position figuring I must have
> accidentally kicked it while getting to some stuff in the baggage
> compartment of my RV-6A.
>
> It was getting late and being a bit tired not to mention stressed, I
> needed to get a rental car and a motel for the night. Did that, eat
> dinner and went to bed after sitting down and drawing out a problem
> tree with the entire major elements of the electrical system.
>
> So next morning I show up at the hangar early and met Ben, the
> mechanic, the battery had received a charge of only 45 minutes the
> evening before, So I suggested we charged it for another hour and try
> to start the aircraft. Ben suggested a real stress test of the
> battery and NOT charge it anymore. Made sense, so we rolled the
> aircraft out of the hangar. I hopped in, threw a half dozen switches
> and punched the starter button. The engine started on the first prop
> blade rotation - so the battery was clearly OK. The
> engine is humming like a top. So I looked over at the voltmeter
> expecting it to show only around 12.8 volts instead of the 14 volts a
> functioning alternator would produce. Much to both my and Ben's
> surprise the alternator voltage read 14 volts. We loaded the
> alternator by turning on the both l00 watt landing lights, all fuel
> pumps, the pitot heat, etc. The alternator voltage only drops perhaps
> 0.4 volts clearly indicating the alternator could carry the load and
> was OK.
>
> So here I am - battery is OK, alternator is OK - engine is purring
> normally, so clearly this was all a figment of my deteriorating brain
> cells. I loaded up the aircraft and launched to do a few circuits of
> the airport - I did so and all was operating normally and so I radio
> them I was head onward to Texas. While flying (with my only
> functional eyeball on the voltmeter), my mind could not let go of the
> problem and finally the light bulb came on.
>
> The essential bus switch had (for my entire 10 + years of
> flying)always been in the alternator position. The purpose of this
> switch is, of course, to isolate the battery from the alternator
> should the alternator fail - to prevent an alternator problem from
> draining the battery. So in event of an alternator problem, you move
> the switch from alternator to battery. Its call the essential bus
> because you only have the essential things drawing from the battery so
> you wont' drain it as quickly. The idea is to give you time
> (generally around 30 minutes) to find a safe place to land in case of
> alternator failure.
>
>
> Well, at some point I had either (not paying attention) turned the
> switch to battery thinking I was turning the voltmeter switch to
> battery(more on that below) - or accidentally had move the switch
> from alternator to battery without noticing it by kicking it, etc.
> However, it was sort of protected in its position from accidental
> activation. It must have happened during refueling - as I got approx
> 45 minutes down the road on the battery after take off before quality
> battery time started to deteriorate. As the battery voltage fell due
> to the load (and no alternator link to replenish it), electrical
> things (mainly computers first) started acting up until they could not
> longer run the engine. The injectors would not open fully, etc. Then
> as the voltage level further decreased, the master relay which the
> battery held closed and which connected the (fully
> functional) alternator to the rest of the electrical system - opened
> up and removed ALL power from the electrical system. So no radio, no
> gauges, etc.
>
> Oh, another little factor that may have contributed, the voltmeter
> has a tiny toggle switch by it marked ALT BAT1 BAT2 for checking
> alternator battery 1 and battery 2 (which I no longer fly with)
> voltages. Down below It a couple of inches and off to the right is
> the essential bus normal size toggle switch - also marked ALT BAT1
> BAT1. I normally never touch it and don't even think about it. But I
> could have reached for the voltmeter toggle thinking to check my
> battery voltage (which I do as a regular thing) and perhaps distracted
> by something reached a bit further down and instead moved the
> essential bus switch from Alternator to Battery causing this entire
> event. I know that I did not consciously do it. So it is either
> accidental or absence minded activation - either way ends with the
> same results {:>)
>
>
> Now it became clear why it didn't matter which pair of fuel injectors
> I turned off - turning off either pair improved the situation because
> it slightly reduced the electrical load by a few amps - and the engine
> ran slightly better for a few moments. The same thing had happened
> when turning off one of the EFI fuel pumps - but what threw me was the
> alternator voltage continued to be normal during this.
>
> After I knew the cause (switch in wrong position), I decided the
> problem was fixed so no reason to return to NC, and I just continued
> on to Texas.
>
> I know some of you may think that removing my second battery was a
> mistake - but, consider this, having another battery could have meant
> I would have been much further from a suitable airfield before they
> both went south. On the other hand, it might have caused me to at
> least think to throw the essential bus switch to the second battery
> and have the Light bulb come on. Who really knows. But, I have in
> mind a simply addition to my electrical circuit that should help in
> the future.
>
>
> I do want to state that this time when the problems started I DID
> switch fuel tanks - but naturally it had no effect because this time
> it turned out, it was not a fuel problem - not the root cause at
> least.
>
> So what are the lessons learned:
>
> . Put EVERY critical switch on your before-takeoff Check list
> . Perhaps put a guard around such critical switches to force
> conscious activation
> . Don't (hard not to) get overly focused on what you think is the
> problem - consider other possibilities. I thought it was a fuel
> problem (I even switched fuel tanks this time) - it turned out to be
> electrical in its root cause.
> . While the fuel pressure was jumping all over the place and the EGT
> was erratic and engine surging strongly indicating a fuel problem -
> the ultimate cause was electrical. Once the voltage got below a
> certain point the EC2 computer was still trying to pull the injectors
> open, but with the voltage so low it could not do it properly.
> . When the battery voltage dropped below a certain point, the master
> relay released and removed the alternator from the electrical system
> and the panel went dark - even though the alternator was still working
> . Immediately turn to the nearest airfield when serious problems
> occur - THEN work on fixing them. I only delayed for perhaps 2-3
> minutes, but that could have made a difference.
> . Watch out for Coffin Corner turn when turning base to final -
> airspeed really bleeds off fast with no engine pulling you along (and
> especially with flaps deployed!)
> . IF you change your mind about landing approach type - remember to
> reconfigure your aircraft for the last decision - I had left my flaps
> deployed when I should have remembered to retracted them. Did that
> help prevent a Coffin Corner stall and spin or would it have put me
> closer to it?
> . You must increase airspeed over the wing to get the sufficient
> energy to over come a high sink rate. Pulling back on the stick when
> the ground is staring you in the face is the natural reaction - but,
> pushing forward to lower the nose is the correct action - providing of
> course you have sufficient altitude!
> . Battery life - I had a two year old 680 odyssey battery which I
> maintain a trickle charge on whenever I'm not flying. With two EFI
> fuel pumps, boost pump, injectors, coils, EC2 and radio and just
> having started the engine before take off - this battery lasted 55
> minutes. Well, the last 5 minutes were not quality battery time.
> So in my case, 30 minutes appears to be a very realistic battery life.
> In fact, had I turned off one EFI pump and the boost pump would have
> gained a few more miles. But, if I had recognized the need to turn
> them off at that time (I normally turn them off at cruise altitude),
> then I would have known how to "fix" the problem.
> . I've decided to add a Schokkty diode between my essential bus and
> the alternator - so that as long as the alternator is producing
> sufficient voltage, then the battery will be getting some charge to
> replace the drain. I've also decided to make that switch position a
> check-list item.
>
> So what it boils down to - if I had recognized early on that it was
> an electrical problem and not focused so much on the fuel system, I
> may have noticed the essential bus switch in the wrong position.
> Force yourself to examine other possible causes (easy to say - harder
> to do).
>
> NEVER, NEVER forget that flying the airplane is the first and only
> priority in this type of situation
>
> NEVER, NEVER forget that saving your butt is the ultimately end-all
> priority. When I decided that landing on the grass was preferable to
> putting a hole in their concrete - I may have made a life-saving
> decision.
>
> So that's my story and I'm sticking to it.
>
> Fly safe, guys!!
>
> Ed
> Ed Anderson
>
>
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Subject: | Re: Essential Incident - Almost (Long) |
Hi Ed
Aren't you glad you weren't flying at night! :-)
A diagram of your electrical system as it was would help us
understand what you did, and why its design caused the failure... Of
particular interest is why switching on the e-bus disconnected the
alternator. I also can't seem to make out why when the main bus still
had power from the alternator, the contactor died when the e-bus
voltage dropped. It may prompt Bob to suggest a better solution to
what you're planning :-D
Not pointing fingers here, I just can't visualise how it's all hooked
up!
Thanks
Etienne
On 03 Jun 2009, at 9:53 PM, Ed Anderson wrote:
> It was suggested by one of the aeroelectric list members, Sam
> Hoskins, that the following report of an incident I had on a
> recent trip be posted to the AeroElectric list for obvious reasons
> ' once you read it.
>
> I have an all-electric Rv-6A with over 10 years and close to 500
> hours on it. I based the electrical system roughly one of Bob=92s
> excellent designs. It initially had one alternator and two
> batteries, but removed the second battery approx 5 years ago ' but,
> I did make one modification to the design that I almost had cause
> to regret.
>
> So needless to say, but I will, responsibility for design and
> incident is totally mine.
>
> But, to get on with the tale
>
>
> One the way to Texas I had an incident that ended up in with me and
> aircraft making a 7 mile engine-out glide into Craig Field (Selma,
> Alabama). NO! It was not fault of the engine or even the
> subsystems. But, the complete answer is not provided until after
> my litany of the conditions and symptoms ' can you figure it out?
>
>
> Fly safe, guys!!
>
> Ed
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