Today's Message Index:
----------------------
1. 07:56 AM - Re: Yak 55M Tail Wheel (mikspin)
2. 10:14 AM - Nanchang vs 18T (skidmk)
3. 10:58 AM - Re: Getting caught off guard, a life and death issue (Roger Kemp M.D.)
4. 02:06 PM - Re: Nanchang vs 18T (Didier Blouzard)
5. 03:01 PM - Engine/avionics shutdown procedure (KingCJ6@aol.com)
6. 03:44 PM - Re: Engine/avionics shutdown procedure (Bitterlich, Mark G CIV Det Cherry Point, MALS-14 64E)
7. 05:39 PM - Re: Engine/avionics shutdown procedure (Steven Johnson)
8. 06:04 PM - Re: Engine/avionics shutdown procedure (Tom Elliott)
9. 06:36 PM - Re: Engine/avionics shutdown procedure (Eric Wobschall)
10. 08:08 PM - Re: Engine/avionics shutdown procedure (Bitterlich, Mark G CIV Det Cherry Point, MALS-14 64E)
11. 10:01 PM - Re: Engine/avionics shutdown procedure (Walter Lannon)
12. 10:55 PM - Re: Engine/avionics shutdown procedure (Didier BLOUZARD)
Message 1
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| Subject: | Re: Yak 55M Tail Wheel |
Flightbag,
Contact Wesley Warner via warner.wesley@gmail.com for info about a very nicely
machined Scott tailwheel housing machined just for the 55 spring.
Mike Hastings
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=313782#313782
Message 2
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Hi all,,, My chang is no longer, and I'm looking for a replacement. I have contemplated
the 18T as there is a nice one for sale here in Canada. Any words of
wisdom? Any problem areas on these ships I should be asking about?
thanks
Mike
--------
Mike "Skidmk" Bourget
Ottawa, Ontario
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=313787#313787
Message 3
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| Subject: | Getting caught off guard, a life and death issue |
Chris,
Glad you survived the prop strike. You are absolutely correct...all
accidents are a sequence of small events the lead up to the big event. The
idea behind safety lectures and articles are to identify those small events
before they become an incident. By your open discussion of your unfortunate
accident you have helped many that may have become complacent in their
pre-flights.
Thanks for your candor.
Doc
-----Original Message-----
From: owner-yak-list-server@matronics.com
[mailto:owner-yak-list-server@matronics.com] On Behalf Of CHRIS ABBOTT
Sent: Friday, September 24, 2010 6:21 PM
Subject: Re: Yak-List: Getting caught off guard, a life and death issue
Guys.
Cant help but to comment, whilst best practices are always good, all
accidents are a sequence of events that until lined up may never happen!
My story goes this way, I have a yak 52 built 1990 VH-YAV, am an avid pilot
(390hrs and 98 in type), Drag racer (2007 championship winner HD Destroyer
9.38sec 147mph ) Flat track racer (HD XR 750, good mates and raced with Jay
Springsteen), a Scuba instructor (wreck, deep 60m+ with over 2000 dives
logged) and in excess of 20 years of experience monitoring and teaching
safety around construction and heavy equipment, ridden motorcycles 1.1
million kilometers including one trip around the world, to base camp tibetan
side, seen war in lebanon "85", Sahara desert, look if it had horsepower,
speed and calculated danger i was into it. Farm raised, a mechanic and
tekkie for some 32 years I am very fastidious about maintenance, build all
my race engines and do all my setups so my yak starts extremely easily!
My sequence of events go this way : - Some 18 months prior to getting in the
way of the prop i had treatment for cancer and subsequent chemo, with this a
couple of business worries and a foggy head! during the whole 18 month
period of treatment and recovery i had to attend to business (partner rip
off problems), this left me with a "busy mind".
At midday on April 4th 2008, even though the night before we had a late one
(tired but not hung over) i dragged the yak out to take a client for a "deal
clincher", done my normal pre flight and noticed that both the battery and
air was a little low during this i received an argumentative phone call from
a previous supplier of the business, after i sat for a while to try to calm
down, a short time had elapsed and i felt ready to go ahead, primed the
engine, jumped in the cockpit to fire it up and taxi to the fuel bowser,
whilst even though it started easily with the low air and battery it stopped
quickly ! this then lead to the sequence that would end in tears, i was
concerned that if i just primed and tried starting on the air it would not
have enough to pull the fuel through so i jumped out to pull through by hand
and to conserve air, looked back to do a check "mags off etc" and reverted
to my instinct of turning things anti clock ways for "off"
and subsequently turned the mags on, the little voice told me this was
incorrect but i assured myself it wasn't (no glasses didn't check the
numbers), slid over the front of the wing to make it quicker (didn't touch
the prop!) checked the oil drain to make sure that it was closed (once again
didn't touch the prop) looked at the prop, it was at approximately the 1:35
position, made the decision to pull it down to a position where i could get
to it easily, i stepped in and reached under the blade rather than lift the
lower blade (quicker this was the final sequence that would see me in and
out of surgery for the next couple of years), as as soon as i touched it it
immediately fired backwards for about 3 blades (fortunately as this pushed
me back) then jumped into a very nice fast forward idle striking my arms and
legs as i tried getting out of the way.
The sequence of events that lined up were as follows
. Tired.
. Busy Brain.
. Distracted by phone call.
. Low air (start solenoid was partially activated).
. Low battery (shower of sparks remained active).
. In a hurry and happy to accept the low air and battery.
. Compromised standing position and sequence for pulling through.
The engrained safety in me saved a much worse incident as i had applied
the brake, turned on the air and never once placed my head or the core of my
body in a position of rotating danger.
Hope this helps to keep the sequences out of sync and a sense of what can
happen when distracted (couple of photos attached to remind)
Message 4
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| Subject: | Re: Nanchang vs 18T |
Hi Mike,
owner of a 18T since 2 years.
Like nearly all yaks no problems if you take care of her.
The pleasure of traveling with three passengers and with a lot of room, with
the pleasure of simple positive aerobatic.
I am not objective as I love her since the beginning and she never falied
me.
Very stable but reactive
Beautiful line and comfortable conditions of flight.
The weak points are on the gears 'corrosion of the actators, corrosion of
the uplock cylinders) but with a regular maintenance there is no weak point.
The point is to purge the water in the air system systematicaly to avoid
water in the air circuit.
I don't speak about the engine because it is the same as on all yaks and
Nanchang.
regards
Diider
2010/9/26 skidmk <skidmk@gmail.com>
>
> Hi all,,, My chang is no longer, and I'm looking for a replacement. I have
> contemplated the 18T as there is a nice one for sale here in Canada. Any
> words of wisdom? Any problem areas on these ships I should be asking about?
>
> thanks
>
> Mike
>
> --------
> Mike "Skidmk" Bourget
> Ottawa, Ontario
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=313787#313787
>
>
--
Didier BLOUZARD
didier.blouzard@gmail.com
0624243672
Message 5
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| Subject: | Engine/avionics shutdown procedure |
Most Nanchang checklists specify shutting the engine down with mags prior
to shutting off the electric switches which power all of the avionics. All
traditional GA checklists I've seen specify turning off the avionics
master (or individual components) prior to shutting down the engine to
presumably prevent damage from a potential power spike. Any technical reason
for
the Nanchang to be different?
Dave
Message 6
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| Subject: | Engine/avionics shutdown procedure |
Dave, That is a very good point. Again, I must caution anyone reading this that
I have never worked on a CJ, though I am aware that they have two types of
control systems for the generator.
I believe there is a solid state controller and also a older more traditional style
controller. Whatever. Let's just cut to the chase. It would be much smarter
to turn off your avionics before killing the mags (engine) if you have anything
in there worth worrying about.
Why? Because on any engine that has a generator, when you kill the mags, the generator
stops turning. As it slows down, the generator voltage will drop below
the battery voltage. When this happens, current stops flowing from the generator
to the battery, and instead flows from the battery to the generator. This
is called "Reverse Current". In all aircraft with real generators, there
is some device that is in there to prevent this.
Or at least... normally the way it works is that as current STARTS flowing from
the battery to the generator, There is usually some kind of "set point" where
this relay operates and then DISCONNECTS the generator from the aircrafts electrical
bus.
Here is the problem. If your battery is not in just TIP TOP condition... which
by the way, many of our batteries are not... because we fail to CHECK THEM PROPERLY.....
what will happen is that when the engine starts slowing down to a
stop after you kill the mags, reverse current will start to flow. If your batteries
are not up to snuff, then the battery output voltage will drop as the
current going to the generator increases.
Hopefully, eventually the current will rise high enough to where the reverse current
RELAY operates and then disconnects the generator. However, that does not
HAVE to happen right away when it should. If the batteries are WEAK, then
this chain of events will happen much more SLOWYLY. And that is a bad bad thing,
because then your battery voltage will drop way down below 24 volts and maybe
as low as 14-16 VDC. Avionics systems really don't like voltage spikes like
this. Going down, or going up They just don't like that kind of thing. Will
it cause instant failure of your avionics? NO. Is it asking for a failure?
YES. Shut off your avionics before killing the engine is the smart thing
to do, regardless of what any check list currently says.
Mark Bitterlich
p.s. I do not bother to follow my own advice, but then I check my batteries carefully
all the time, and I also am only powering one Russian radio. But, I really
should, and if I had any Avionics that cost more than a few hundred, I would
be religious about it.
________________________________
From: owner-yak-list-server@matronics.com on behalf of KingCJ6@aol.com
Sent: Sun 9/26/2010 5:58 PM
Subject: Yak-List: Engine/avionics shutdown procedure
Most Nanchang checklists specify shutting the engine down with mags prior to shutting
off the electric switches which power all of the avionics. All traditional
GA checklists I've seen specify turning off the avionics master (or individual
components) prior to shutting down the engine to presumably prevent damage
from a potential power spike. Any technical reason for the Nanchang to be
different?
Dave
Message 7
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| Subject: | Engine/avionics shutdown procedure |
Mark, how does one check the batteries properly?
Steve Johnson
Yak 52 N9900X 0B5
413 522-1130 Cell
-----Original Message-----
From: owner-yak-list-server@matronics.com
[mailto:owner-yak-list-server@matronics.com] On Behalf Of Bitterlich, Mark G
CIV Det Cherry Point, MALS-14 64E
Sent: Sunday, September 26, 2010 6:29 PM
Subject: RE: Yak-List: Engine/avionics shutdown procedure
--> Point, MALS-14 64E" <mark.bitterlich@navy.mil>
Dave, That is a very good point. Again, I must caution anyone reading this
that I have never worked on a CJ, though I am aware that they have two types
of control systems for the generator.
I believe there is a solid state controller and also a older more
traditional style controller. Whatever. Let's just cut to the chase. It
would be much smarter to turn off your avionics before killing the mags
(engine) if you have anything in there worth worrying about.
Why? Because on any engine that has a generator, when you kill the mags,
the generator stops turning. As it slows down, the generator voltage will
drop below the battery voltage. When this happens, current stops flowing
from the generator to the battery, and instead flows from the battery to the
generator. This is called "Reverse Current". In all aircraft with real
generators, there is some device that is in there to prevent this.
Or at least... normally the way it works is that as current STARTS flowing
from the battery to the generator, There is usually some kind of "set
point" where this relay operates and then DISCONNECTS the generator from the
aircrafts electrical bus.
Here is the problem. If your battery is not in just TIP TOP condition...
which by the way, many of our batteries are not... because we fail to CHECK
THEM PROPERLY..... what will happen is that when the engine starts slowing
down to a stop after you kill the mags, reverse current will start to flow.
If your batteries are not up to snuff, then the battery output voltage will
drop as the current going to the generator increases.
Hopefully, eventually the current will rise high enough to where the reverse
current RELAY operates and then disconnects the generator. However, that
does not HAVE to happen right away when it should. If the batteries are
WEAK, then this chain of events will happen much more SLOWYLY. And that is
a bad bad thing, because then your battery voltage will drop way down below
24 volts and maybe as low as 14-16 VDC. Avionics systems really don't like
voltage spikes like this. Going down, or going up They just don't like
that kind of thing. Will it cause instant failure of your avionics? NO. Is
it asking for a failure? YES. Shut off your avionics before killing the
engine is the smart thing to do, regardless of what any check list currently
says.
Mark Bitterlich
p.s. I do not bother to follow my own advice, but then I check my batteries
carefully all the time, and I also am only powering one Russian radio. But,
I really should, and if I had any Avionics that cost more than a few
hundred, I would be religious about it.
________________________________
From: owner-yak-list-server@matronics.com on behalf of KingCJ6@aol.com
Sent: Sun 9/26/2010 5:58 PM
Subject: Yak-List: Engine/avionics shutdown procedure
Most Nanchang checklists specify shutting the engine down with mags prior to
shutting off the electric switches which power all of the avionics. All
traditional GA checklists I've seen specify turning off the avionics master
(or individual components) prior to shutting down the engine to presumably
prevent damage from a potential power spike. Any technical reason for the
Nanchang to be different?
Dave
Message 8
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| Subject: | Engine/avionics shutdown procedure |
Do you have a generator or an Alternator ? With the Alt no issue, with the
generator possibly depending on your battery and reverse current relay. I
have mostly
turned off the master and or avionics after engine shut down for many years
and have had no problems.
Tom Elliott
CJ-6A NX63727
702-595-2680
_____
From: owner-yak-list-server@matronics.com
[mailto:owner-yak-list-server@matronics.com] On Behalf Of KingCJ6@aol.com
Sent: Sunday, September 26, 2010 2:59 PM
Subject: Yak-List: Engine/avionics shutdown procedure
Most Nanchang checklists specify shutting the engine down with mags prior to
shutting off the electric switches which power all of the avionics. All
traditional GA checklists I've seen specify turning off the avionics master
(or individual components) prior to shutting down the engine to presumably
prevent damage from a potential power spike. Any technical reason for the
Nanchang to be different?
Dave
Message 9
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| Subject: | Re: Engine/avionics shutdown procedure |
Im the Yak-52, I turn off all of the left side switches except engine
instruments (which I never turn off) during the pre-shutdown run-up.
On Sep 26, 2010, at 5:58 PM, KingCJ6@aol.com wrote:
> Most Nanchang checklists specify shutting the engine down with mags
> prior to shutting off the electric switches which power all of the
> avionics. All traditional GA checklists I've seen specify turning
> off the avionics master (or individual components) prior to shutting
> down the engine to presumably prevent damage from a potential power
> spike. Any technical reason for the Nanchang to be different?
>
> Dave
>
>
Message 10
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| Subject: | Engine/avionics shutdown procedure |
Steve, that is yet another good question. Most of us these days are using gell
cell batteries so checking the specific gravity of the electrolyte is just
not do-able.
So, another method is easy and very simple but it is not something you can tape
to a calibration table per se.
Batteries that are in "good shape" (a very loose term) will hold their voltage
for awhile when you put a load on them. If you notice, most of those gell cells
we stick in there have an amp/hour rating. What this means is that you can
draw that number of amps continuously for one hour. You can do some math with
this and interpolate accordingly. You can get pretty fancy with this if you
want to.
But the plain and simple method is pretty straight forward. Most YAK's and I believe
CJ's, have a voltage and amp meter built into the aircraft. Turn on the
electrical master. BEFORE you go flying. Look at the voltage. It should be
around 24 volts or so, maybe as high as 25. If it down around 22 vdc, your
eyebrows should start going up in alarm. At this point, start turning on anything
that draws a lot of current. Landing lights would be good. So is Pitot
Heat. Radios, no. As you turn this stuff on, look at that battery voltage.
Is it HOLDING? Or is it dropping like a stone? If you had 22-23 VDC and you
turn on Pitot Heat and it drops to 20 vdc... HMMM!!! If you then turn on a
landing light.... and it drops to 16-18 volts OR LESS, then it is time to replace
the batteries. A much better way is to put a good digital meter on the battery
terminals themselves when you do this by the way and read the voltage with
that.
Do not check them and come back and say: HEY, ONE IS 12 VOLTS AND ONE IS 6 VOLTS,
SO I AM ONLY GOING TO REPLACE ONE!!! Yeah, that will work, but it it is penny
wise and dollar foolish. You want all the cells in the two 12 volt batteries
that you connect in series to get 24 volts to be BALANCED. If they are NOT
balanced, then the current to charge the WEAK cells has to flow through the
GOOD cells to charge the weak ones. This ends up over-charging the GOOD cells
and causing them to vent gas. Which makes them go bad. Quickly.
SO ... try to replace them in PAIRS.
I don't want to sound like an advertisement, but I really am impressed with Battery-Minder
battery chargers. They not only have a temp. sensor that keeps from
overheating charging batteries, but also, after the batteries are charged,
they put a 3 Mhz blast pulse into the batteries that works to turn battery sulfate
off the plates and put it back into solution, or.... "gell" that extends
the life of the battery PLUS they check the status of the battery automatically.
They are not cheap. But.... They are worth every cent in my opinion. I
own THREE of them.
The YAK and CJ's aircraft for the most part do not use electrical starters (Some
rare models excepted). An electrical starter is a quick test for a battery.
I.E. Think of your car when it gets cold. Bad battery? You don't start,
so you replace it. We do not have that huge electrical draw that the car starter
represents... so our batteries kind of go bad in a sneaky way. Leading to
issues with the reverse current relay.
Just had a nice person with a YAK-18T that this just happened to. Hope this explains
what is happening, and how to keep an eye out for it.
Mark
________________________________
From: owner-yak-list-server@matronics.com on behalf of Steven Johnson
Sent: Sun 9/26/2010 8:18 PM
Subject: RE: Yak-List: Engine/avionics shutdown procedure
Mark, how does one check the batteries properly?
Steve Johnson
Yak 52 N9900X 0B5
413 522-1130 Cell
-----Original Message-----
From: owner-yak-list-server@matronics.com
[mailto:owner-yak-list-server@matronics.com] On Behalf Of Bitterlich, Mark G
CIV Det Cherry Point, MALS-14 64E
Sent: Sunday, September 26, 2010 6:29 PM
Subject: RE: Yak-List: Engine/avionics shutdown procedure
--> Point, MALS-14 64E" <mark.bitterlich@navy.mil>
Dave, That is a very good point. Again, I must caution anyone reading this
that I have never worked on a CJ, though I am aware that they have two types
of control systems for the generator.
I believe there is a solid state controller and also a older more
traditional style controller. Whatever. Let's just cut to the chase. It
would be much smarter to turn off your avionics before killing the mags
(engine) if you have anything in there worth worrying about.
Why? Because on any engine that has a generator, when you kill the mags,
the generator stops turning. As it slows down, the generator voltage will
drop below the battery voltage. When this happens, current stops flowing
from the generator to the battery, and instead flows from the battery to the
generator. This is called "Reverse Current". In all aircraft with real
generators, there is some device that is in there to prevent this.
Or at least... normally the way it works is that as current STARTS flowing
from the battery to the generator, There is usually some kind of "set
point" where this relay operates and then DISCONNECTS the generator from the
aircrafts electrical bus.
Here is the problem. If your battery is not in just TIP TOP condition...
which by the way, many of our batteries are not... because we fail to CHECK
THEM PROPERLY..... what will happen is that when the engine starts slowing
down to a stop after you kill the mags, reverse current will start to flow.
If your batteries are not up to snuff, then the battery output voltage will
drop as the current going to the generator increases.
Hopefully, eventually the current will rise high enough to where the reverse
current RELAY operates and then disconnects the generator. However, that
does not HAVE to happen right away when it should. If the batteries are
WEAK, then this chain of events will happen much more SLOWYLY. And that is
a bad bad thing, because then your battery voltage will drop way down below
24 volts and maybe as low as 14-16 VDC. Avionics systems really don't like
voltage spikes like this. Going down, or going up They just don't like
that kind of thing. Will it cause instant failure of your avionics? NO. Is
it asking for a failure? YES. Shut off your avionics before killing the
engine is the smart thing to do, regardless of what any check list currently
says.
Mark Bitterlich
p.s. I do not bother to follow my own advice, but then I check my batteries
carefully all the time, and I also am only powering one Russian radio. But,
I really should, and if I had any Avionics that cost more than a few
hundred, I would be religious about it.
________________________________
From: owner-yak-list-server@matronics.com on behalf of KingCJ6@aol.com
Sent: Sun 9/26/2010 5:58 PM
Subject: Yak-List: Engine/avionics shutdown procedure
Most Nanchang checklists specify shutting the engine down with mags prior to
shutting off the electric switches which power all of the avionics. All
traditional GA checklists I've seen specify turning off the avionics master
(or individual components) prior to shutting down the engine to presumably
prevent damage from a potential power spike. Any technical reason for the
Nanchang to be different?
Dave
Message 11
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| Subject: | Re: Engine/avionics shutdown procedure |
Thanks Mark;
Great information. Do you have a recommendation for which Battery- Minder to
get?
Walt
----- Original Message -----
From: "Bitterlich, Mark G CIV Det Cherry Point, MALS-14 64E"
<mark.bitterlich@navy.mil>
Sent: Sunday, September 26, 2010 8:04 PM
Subject: RE: Yak-List: Engine/avionics shutdown procedure
> MALS-14 64E" <mark.bitterlich@navy.mil>
>
> Steve, that is yet another good question. Most of us these days are
> using gell cell batteries so checking the specific gravity of the
> electrolyte is just not do-able.
>
> So, another method is easy and very simple but it is not something you can
> tape to a calibration table per se.
>
> Batteries that are in "good shape" (a very loose term) will hold their
> voltage for awhile when you put a load on them. If you notice, most of
> those gell cells we stick in there have an amp/hour rating. What this
> means is that you can draw that number of amps continuously for one hour.
> You can do some math with this and interpolate accordingly. You can get
> pretty fancy with this if you want to.
>
> But the plain and simple method is pretty straight forward. Most YAK's
> and I believe CJ's, have a voltage and amp meter built into the aircraft.
> Turn on the electrical master. BEFORE you go flying. Look at the
> voltage. It should be around 24 volts or so, maybe as high as 25. If it
> down around 22 vdc, your eyebrows should start going up in alarm. At this
> point, start turning on anything that draws a lot of current. Landing
> lights would be good. So is Pitot Heat. Radios, no. As you turn this
> stuff on, look at that battery voltage. Is it HOLDING? Or is it dropping
> like a stone? If you had 22-23 VDC and you turn on Pitot Heat and it
> drops to 20 vdc... HMMM!!! If you then turn on a landing light.... and
> it drops to 16-18 volts OR LESS, then it is time to replace the batteries.
> A much better way is to put a good digital meter on the battery terminals
> themselves when you do this by the way and read the voltage with that.
>
> Do not check them and come back and say: HEY, ONE IS 12 VOLTS AND ONE IS 6
> VOLTS, SO I AM ONLY GOING TO REPLACE ONE!!! Yeah, that will work, but it
> it is penny wise and dollar foolish. You want all the cells in the two 12
> volt batteries that you connect in series to get 24 volts to be BALANCED.
> If they are NOT balanced, then the current to charge the WEAK cells has to
> flow through the GOOD cells to charge the weak ones. This ends up
> over-charging the GOOD cells and causing them to vent gas. Which makes
> them go bad. Quickly.
>
> SO ... try to replace them in PAIRS.
>
> I don't want to sound like an advertisement, but I really am impressed
> with Battery-Minder battery chargers. They not only have a temp. sensor
> that keeps from overheating charging batteries, but also, after the
> batteries are charged, they put a 3 Mhz blast pulse into the batteries
> that works to turn battery sulfate off the plates and put it back into
> solution, or.... "gell" that extends the life of the battery PLUS they
> check the status of the battery automatically. They are not cheap.
> But.... They are worth every cent in my opinion. I own THREE of them.
>
> The YAK and CJ's aircraft for the most part do not use electrical starters
> (Some rare models excepted). An electrical starter is a quick test for a
> battery. I.E. Think of your car when it gets cold. Bad battery? You
> don't start, so you replace it. We do not have that huge electrical draw
> that the car starter represents... so our batteries kind of go bad in a
> sneaky way. Leading to issues with the reverse current relay.
>
> Just had a nice person with a YAK-18T that this just happened to. Hope
> this explains what is happening, and how to keep an eye out for it.
>
> Mark
>
>
> ________________________________
>
> From: owner-yak-list-server@matronics.com on behalf of Steven Johnson
> Sent: Sun 9/26/2010 8:18 PM
> To: yak-list@matronics.com
> Subject: RE: Yak-List: Engine/avionics shutdown procedure
>
>
>
> Mark, how does one check the batteries properly?
>
> Steve Johnson
> Yak 52 N9900X 0B5
> 413 522-1130 Cell
> -----Original Message-----
> From: owner-yak-list-server@matronics.com
> [mailto:owner-yak-list-server@matronics.com] On Behalf Of Bitterlich, Mark
> G
> CIV Det Cherry Point, MALS-14 64E
> Sent: Sunday, September 26, 2010 6:29 PM
> To: yak-list@matronics.com
> Subject: RE: Yak-List: Engine/avionics shutdown procedure
>
> --> Point, MALS-14 64E" <mark.bitterlich@navy.mil>
>
> Dave, That is a very good point. Again, I must caution anyone reading
> this
> that I have never worked on a CJ, though I am aware that they have two
> types
> of control systems for the generator.
>
> I believe there is a solid state controller and also a older more
> traditional style controller. Whatever. Let's just cut to the chase. It
> would be much smarter to turn off your avionics before killing the mags
> (engine) if you have anything in there worth worrying about.
>
> Why? Because on any engine that has a generator, when you kill the mags,
> the generator stops turning. As it slows down, the generator voltage will
> drop below the battery voltage. When this happens, current stops flowing
> from the generator to the battery, and instead flows from the battery to
> the
> generator. This is called "Reverse Current". In all aircraft with real
> generators, there is some device that is in there to prevent this.
>
> Or at least... normally the way it works is that as current STARTS flowing
> from the battery to the generator, There is usually some kind of "set
> point" where this relay operates and then DISCONNECTS the generator from
> the
> aircrafts electrical bus.
>
> Here is the problem. If your battery is not in just TIP TOP condition...
> which by the way, many of our batteries are not... because we fail to
> CHECK
> THEM PROPERLY..... what will happen is that when the engine starts
> slowing
> down to a stop after you kill the mags, reverse current will start to
> flow.
> If your batteries are not up to snuff, then the battery output voltage
> will
> drop as the current going to the generator increases.
>
> Hopefully, eventually the current will rise high enough to where the
> reverse
> current RELAY operates and then disconnects the generator. However, that
> does not HAVE to happen right away when it should. If the batteries are
> WEAK, then this chain of events will happen much more SLOWYLY. And that
> is
> a bad bad thing, because then your battery voltage will drop way down
> below
> 24 volts and maybe as low as 14-16 VDC. Avionics systems really don't
> like
> voltage spikes like this. Going down, or going up They just don't like
> that kind of thing. Will it cause instant failure of your avionics? NO.
> Is
> it asking for a failure? YES. Shut off your avionics before killing the
> engine is the smart thing to do, regardless of what any check list
> currently
> says.
>
> Mark Bitterlich
>
> p.s. I do not bother to follow my own advice, but then I check my
> batteries
> carefully all the time, and I also am only powering one Russian radio.
> But,
> I really should, and if I had any Avionics that cost more than a few
> hundred, I would be religious about it.
>
> ________________________________
>
> From: owner-yak-list-server@matronics.com on behalf of KingCJ6@aol.com
> Sent: Sun 9/26/2010 5:58 PM
> To: yak-list@matronics.com
> Subject: Yak-List: Engine/avionics shutdown procedure
>
>
> Most Nanchang checklists specify shutting the engine down with mags prior
> to
> shutting off the electric switches which power all of the avionics. All
> traditional GA checklists I've seen specify turning off the avionics
> master
> (or individual components) prior to shutting down the engine to presumably
> prevent damage from a potential power spike. Any technical reason for the
> Nanchang to be different?
>
>
> Dave
>
>
>
Message 12
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| Subject: | Re: Engine/avionics shutdown procedure |
Yeah
I also would like to have one or plus recommendation please
Regards
Didier Blouzard
+33 6 2424 3672
Le 27 sept. 2010 06:41, Walter Lannon <wlannon@persona.ca> a crit :
>
> Thanks Mark;
>
> Great information. Do you have a recommendation for which Battery- Minder to
get?
>
> Walt
> ----- Original Message ----- From: "Bitterlich, Mark G CIV Det Cherry Point,
MALS-14 64E" <mark.bitterlich@navy.mil>
> To: <yak-list@matronics.com>
> Sent: Sunday, September 26, 2010 8:04 PM
> Subject: RE: Yak-List: Engine/avionics shutdown procedure
>
>
>>
>> Steve, that is yet another good question. Most of us these days are using
gell cell batteries so checking the specific gravity of the electrolyte is just
not do-able.
>>
>> So, another method is easy and very simple but it is not something you can tape
to a calibration table per se.
>>
>> Batteries that are in "good shape" (a very loose term) will hold their voltage
for awhile when you put a load on them. If you notice, most of those gell
cells we stick in there have an amp/hour rating. What this means is that you
can draw that number of amps continuously for one hour. You can do some math with
this and interpolate accordingly. You can get pretty fancy with this if you
want to.
>>
>> But the plain and simple method is pretty straight forward. Most YAK's and
I believe CJ's, have a voltage and amp meter built into the aircraft. Turn on
the electrical master. BEFORE you go flying. Look at the voltage. It should
be around 24 volts or so, maybe as high as 25. If it down around 22 vdc, your
eyebrows should start going up in alarm. At this point, start turning on anything
that draws a lot of current. Landing lights would be good. So is Pitot
Heat. Radios, no. As you turn this stuff on, look at that battery voltage.
Is it HOLDING? Or is it dropping like a stone? If you had 22-23 VDC and
you turn on Pitot Heat and it drops to 20 vdc... HMMM!!! If you then turn on
a landing light.... and it drops to 16-18 volts OR LESS, then it is time to replace
the batteries. A much better way is to put a good digital meter on the
battery terminals themselves when you do this by the way and read the voltage
with that.
>>
>> Do not check them and come back and say: HEY, ONE IS 12 VOLTS AND ONE IS 6 VOLTS,
SO I AM ONLY GOING TO REPLACE ONE!!! Yeah, that will work, but it it is
penny wise and dollar foolish. You want all the cells in the two 12 volt batteries
that you connect in series to get 24 volts to be BALANCED. If they are
NOT balanced, then the current to charge the WEAK cells has to flow through the
GOOD cells to charge the weak ones. This ends up over-charging the GOOD cells
and causing them to vent gas. Which makes them go bad. Quickly.
>>
>> SO ... try to replace them in PAIRS.
>>
>> I don't want to sound like an advertisement, but I really am impressed with
Battery-Minder battery chargers. They not only have a temp. sensor that keeps
from overheating charging batteries, but also, after the batteries are charged,
they put a 3 Mhz blast pulse into the batteries that works to turn battery
sulfate off the plates and put it back into solution, or.... "gell" that extends
the life of the battery PLUS they check the status of the battery automatically.
They are not cheap. But.... They are worth every cent in my opinion.
I own THREE of them.
>>
>> The YAK and CJ's aircraft for the most part do not use electrical starters (Some
rare models excepted). An electrical starter is a quick test for a battery.
I.E. Think of your car when it gets cold. Bad battery? You don't start,
so you replace it. We do not have that huge electrical draw that the car starter
represents... so our batteries kind of go bad in a sneaky way. Leading
to issues with the reverse current relay.
>>
>> Just had a nice person with a YAK-18T that this just happened to. Hope this
explains what is happening, and how to keep an eye out for it.
>>
>> Mark
>>
>>
>> ________________________________
>>
>> From: owner-yak-list-server@matronics.com on behalf of Steven Johnson
>> Sent: Sun 9/26/2010 8:18 PM
>> To: yak-list@matronics.com
>> Subject: RE: Yak-List: Engine/avionics shutdown procedure
>>
>>
>>
>>
>> Mark, how does one check the batteries properly?
>>
>> Steve Johnson
>> Yak 52 N9900X 0B5
>> 413 522-1130 Cell
>> -----Original Message-----
>> From: owner-yak-list-server@matronics.com
>> [mailto:owner-yak-list-server@matronics.com] On Behalf Of Bitterlich, Mark G
>> CIV Det Cherry Point, MALS-14 64E
>> Sent: Sunday, September 26, 2010 6:29 PM
>> To: yak-list@matronics.com
>> Subject: RE: Yak-List: Engine/avionics shutdown procedure
>>
>> --> Point, MALS-14 64E" <mark.bitterlich@navy.mil>
>>
>> Dave, That is a very good point. Again, I must caution anyone reading this
>> that I have never worked on a CJ, though I am aware that they have two types
>> of control systems for the generator.
>>
>> I believe there is a solid state controller and also a older more
>> traditional style controller. Whatever. Let's just cut to the chase. It
>> would be much smarter to turn off your avionics before killing the mags
>> (engine) if you have anything in there worth worrying about.
>>
>> Why? Because on any engine that has a generator, when you kill the mags,
>> the generator stops turning. As it slows down, the generator voltage will
>> drop below the battery voltage. When this happens, current stops flowing
>> from the generator to the battery, and instead flows from the battery to the
>> generator. This is called "Reverse Current". In all aircraft with real
>> generators, there is some device that is in there to prevent this.
>>
>> Or at least... normally the way it works is that as current STARTS flowing
>> from the battery to the generator, There is usually some kind of "set
>> point" where this relay operates and then DISCONNECTS the generator from the
>> aircrafts electrical bus.
>>
>> Here is the problem. If your battery is not in just TIP TOP condition...
>> which by the way, many of our batteries are not... because we fail to CHECK
>> THEM PROPERLY..... what will happen is that when the engine starts slowing
>> down to a stop after you kill the mags, reverse current will start to flow.
>> If your batteries are not up to snuff, then the battery output voltage will
>> drop as the current going to the generator increases.
>>
>> Hopefully, eventually the current will rise high enough to where the reverse
>> current RELAY operates and then disconnects the generator. However, that
>> does not HAVE to happen right away when it should. If the batteries are
>> WEAK, then this chain of events will happen much more SLOWYLY. And that is
>> a bad bad thing, because then your battery voltage will drop way down below
>> 24 volts and maybe as low as 14-16 VDC. Avionics systems really don't like
>> voltage spikes like this. Going down, or going up They just don't like
>> that kind of thing. Will it cause instant failure of your avionics? NO. Is
>> it asking for a failure? YES. Shut off your avionics before killing the
>> engine is the smart thing to do, regardless of what any check list currently
>> says.
>>
>> Mark Bitterlich
>>
>> p.s. I do not bother to follow my own advice, but then I check my batteries
>> carefully all the time, and I also am only powering one Russian radio. But,
>> I really should, and if I had any Avionics that cost more than a few
>> hundred, I would be religious about it.
>>
>> ________________________________
>>
>> From: owner-yak-list-server@matronics.com on behalf of KingCJ6@aol.com
>> Sent: Sun 9/26/2010 5:58 PM
>> To: yak-list@matronics.com
>> Subject: Yak-List: Engine/avionics shutdown procedure
>>
>>
>>
>> Most Nanchang checklists specify shutting the engine down with mags prior to
>> shutting off the electric switches which power all of the avionics. All
>> traditional GA checklists I've seen specify turning off the avionics master
>> (or individual components) prior to shutting down the engine to presumably
>> prevent damage from a potential power spike. Any technical reason for the
>> Nanchang to be different?
>>
>>
>>
>> Dave
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>
>
>
>
>
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