Today's Message Index:
----------------------
1. 06:56 AM - Re: Voltage drop (Robert L. Nuckolls, III)
2. 07:04 AM - Re: Voltage drop (Robert L. Nuckolls, III)
3. 08:49 AM - Re: Voltage drop (Robert L. Nuckolls, III)
4. 09:19 AM - Re: Voltage drop (ashleysc@broadstripe.net)
5. 12:09 PM - Re: Voltage drop (Robert L. Nuckolls, III)
6. 01:08 PM - EFIS Power Switch (Art Zemon)
7. 01:27 PM - Re: Voltage drop (Chuck Birdsall)
8. 05:13 PM - Re: Voltage drop (Robert L. Nuckolls, III)
9. 06:19 PM - Re: Voltage drop (Jim Baker)
10. 07:16 PM - Re: Voltage drop (ashleysc@broadstripe.net)
11. 07:29 PM - Re: EFIS Power Switch (user9253)
Message 1
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| Subject: | Re: Voltage drop |
At 08:57 PM 8/20/2016, you wrote:
>Thanks Bob,
>
>I do have a backup battery that is already wired
>in but have it disconnected because there is no charging going on.
Don't understand this . . . is this a system
battery that is part of your airplane's architecture
or is it associated with a specific appliance
as part of its design?
>=C2 The other problem is that my odyssey battery
>(680) was more discharged than I thought .=C2 It
>is on a charger now and it should rectify the
>problem. I was just concerned I had a bad relay
>or miss-wired something.=C2 The good news is I
>checked all my wiring Battery/ Alt. switch etc.=C2 They were all fine.
. . . good connecting of the dots . . .
>I do have a basic question that I cannot seem to
>answer in my mind.=C2 When the Battery switch is
>on, there is power going to the alternator via
>the main B lead. Since that lead is connected
>directly to the output side of the battery relay
>dose it not draw a significant amount of current
>when the Battery master is on and the alternator
>is not running.=C2 In you book it show hat=C2 lead
>connected to coils that are stationary in the
>alternator, then to ground believe.=C2 My non
>electrical mind just cannot figure that out.
An alternator generally has two connections
to the ship's electrical system. (1) The "B-Lead"
or battery lead that is a power-output connection
and an input lead that is (2a) excitation from the
regulator to the field . . .
Emacs!
. . . or (2b) on/off control to the internal
regulator.
Emacs!
In both cases, you can see that the B-lead
connects to the + side of a three-phase
rectifier . . . diodes that convert the
internally generated AC into DC while
preventing any back flow of current from
the battery into the alternator.
In all automotive applications, you will find that
the b-lead is always connected to the vehicle's
battery. The factory stock (+) battery cable for
my truck comes with two wires, a fat wire to the
starter solenoid and a not-so-fat wire running
directly to the alternator b-lead - power never
flows into this lead as long as the diodes
are intact.
The only 'input' lead to an externally regulated
alternator draws current when the alternator
control switch is ON. This is field current
from the regulator attempting to control
bus voltage. If the engine is not yet running,
the regulator will 'full field' the alternator
causing as much as 3 amps of draw on the
battery.
The modern internally regulated alternator
often features an integrated circuit that
'watches' for the presence of ac voltage
from the stator windings. If no AC present
then the alternator is not rotating . . . and
field current is shut off. This prevents
the otherwise inevitable, non-productive
drain during times the engine is not running.
>It's been 5 years since I retired, but I do
>remember some screen interruption, all be it
>small and fast during engine starts on some if
>not all the planes I flew to make a buck.=C2 Usually when changing from
>APU power to the engine driven generators. =C2 I
>guess its just part of the program
Correct. This is a function of time-to-boot-up
inherent in the design of the appliance.
As I recall, all of the screens in the
line of Beech products pretty much came
alive in a second or less after application
of operating power whether first-on or
post brown-out . . . so we KNOW it can
be done. All of my software driven products
are wide-eyed, bright-eyed and bushy-tailed
milliseconds after power up.
But ever since the Blue Mountain days of
EFIS products offered to owner built and
maintained aircraft, there have be a variety
of instances where boot-up times were sometimes
distressingly long (Blue Mountain had a HARD
DRIVE!!). So not only did that product
need to load an operating system, it might
take many seconds after the software woke
up until the analog rate integration
calculations could get stood up in deducing
the gravity vector.
We've come a long way baby . . . but it's
still disappointing that some of the big
guns in the electronic instrumentation
business for light aircraft are not not
implementing the best we know how to do
in managing power-up/brown-outs events.
Bob . . .
Message 2
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| Subject: | Re: Voltage drop |
At 06:59 PM 8/20/2016, you wrote:
>
>The only situation I have experienced where oil pressure response
>time was important is for a cold start, as in below freezing, where
>the amount of pre-heat is questionable as to whether it was applied
>long enough. As in if pressure doesn't come up in 30 seconds, one
>should shut down and apply heat longer to the engine compartment.
>Seems like some electrowhizzy engine monitors take 30 seconds to
>boot. On the other hand, most of them respond well to a small backup
>battery that keeps input voltage high enough to prevent a reboot.
Yeah. I recall getting ready to depart
Kansas City one morning when the airplane
had sat out in -10F weather. We heated the
engine and used ground power to supplement
a cold battery. Engine started readily
but the oil pressure didn't really start to
move for a really long time (didn't have the stop
watch out). The oil pressure gage was connected
to the engine through a small bore copper line.
Oil in that line behind the fire wall did not
get warmed in pre-heat . . . and was essentially
the consistency of peanut butter.
Under some circumstances, even the legacy
steam gage can take some time to offer useful
information.
Bob . . .
Message 3
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| Subject: | Re: Voltage drop |
Posted this eariler and got a bounce from the
ListServer about having exceeded attachment
limits. Need to look into that.
In the mean time, here's a repost with links
to images:
At 08:57 PM 8/20/2016, you wrote:
>Thanks Bob,
>
>I do have a backup battery that is already wired
>in but have it disconnected because there is no charging going on.
Don't understand this . . . is this a system
battery that is part of your airplane's architecture
or is it associated with a specific appliance
as part of its design?
>=C2 The other problem is that my odyssey battery
>(680) was more discharged than I thought .=C2 It
>is on a charger now and it should rectify the
>problem. I was just concerned I had a bad relay
>or miss-wired something.=C2 The good news is I
>checked all my wiring Battery/ Alt. switch etc.=C2 They were all fine.
. . . good connecting of the dots . . .
>I do have a basic question that I cannot seem to
>answer in my mind.=C2 When the Battery switch is
>on, there is power going to the alternator via
>the main B lead. Since that lead is connected
>directly to the output side of the battery relay
>dose it not draw a significant amount of current
>when the Battery master is on and the alternator
>is not running.=C2 In you book it show hat=C2 lead
>connected to coils that are stationary in the
>alternator, then to ground believe.=C2 My non
>electrical mind just cannot figure that out.
An alternator generally has two connections
to the ship's electrical system. (1) The "B-Lead"
or battery lead that is a power-output connection
and an input lead that is (2a) excitation from the
regulator to the field . . .
http://www.aeroelectric.com/List_Files/Externally_Regulated-s.jpg
. . . or (2b) on/off control to the internal
regulator.
http://www.aeroelectric.com/List_Files/Internally_Regulated-s.jpg
In both cases, you can see that the B-lead
connects to the + side of a three-phase
rectifier . . . diodes that convert the
internally generated AC into DC while
preventing any back flow of current from
the battery into the alternator.
In all automotive applications, you will find that
the b-lead is always connected to the vehicle's
battery. The factory stock (+) battery cable for
my truck comes with two wires, a fat wire to the
starter solenoid and a not-so-fat wire running
directly to the alternator b-lead - power never
flows into this lead as long as the diodes
are intact.
The only 'input' lead to an externally regulated
alternator draws current when the alternator
control switch is ON. This is field current
from the regulator attempting to control
bus voltage. If the engine is not yet running,
the regulator will 'full field' the alternator
causing as much as 3 amps of draw on the
battery.
The modern internally regulated alternator
often features an integrated circuit that
'watches' for the presence of ac voltage
from the stator windings. If no AC present
then the alternator is not rotating . . . and
field current is shut off. This prevents
the otherwise inevitable, non-productive
drain during times the engine is not running.
>It's been 5 years since I retired, but I do
>remember some screen interruption, all be it
>small and fast during engine starts on some if
>not all the planes I flew to make a buck.=C2 Usually when changing from
>APU power to the engine driven generators. =C2 I
>guess its just part of the program
Correct. This is a function of time-to-boot-up
inherent in the design of the appliance.
As I recall, all of the screens in the
line of Beech products pretty much came
alive in a second or less after application
of operating power whether first-on or
post brown-out . . . so we KNOW it can
be done. All of my software driven products
are wide-eyed, bright-eyed and bushy-tailed
milliseconds after power up.
But ever since the Blue Mountain days of
EFIS products offered to owner built and
maintained aircraft, there have be a variety
of instances where boot-up times were sometimes
distressingly long (Blue Mountain had a HARD
DRIVE!!). So not only did that product
need to load an operating system, it might
take many seconds after the software woke
up until the analog rate integration
calculations could get stood up in deducing
the gravity vector.
We've come a long way baby . . . but it's
still disappointing that some of the big
guns in the electronic instrumentation
business for light aircraft are not not
implementing the best we know how to do
in managing power-up/brown-outs events.
Bob . . .
Bob . . .
Message 4
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| Subject: | Re: Voltage drop |
Hi Bob;
Neat and very understandable schematics for externally and internally regul
ated alternators. Would you care to provide one for a internally regulated,
permanent magnet alternator, so as to cover the subject exhaustively? I th
ink I can deduce same, but would feel better to have it "from the horse's m
outh."
Cheers!=C2-=C2- Stu.
----- Original Message -----
From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
Sent: Sunday, August 21, 2016 7:57:50 AM
Subject: Re: AeroElectric-List: Voltage drop
Posted this eariler and got a bounce from the
ListServer about having exceeded attachment
limits. Need to look into that.
In the mean time, here's a repost with links
to images:
At 08:57 PM 8/20/2016, you wrote:
Thanks Bob,
I do have a backup battery that is already wired in but have it disconnecte
d because there is no charging going on.
=C2- Don't understand this . . . is this a system
=C2- battery that is part of your airplane's architecture
=C2- or is it associated with a specific appliance
=C2- as part of its design?
<blockquote>
=C3=82=C2- The other problem is that my odyssey battery (680) was more di
scharged than I thought .=C3=82=C2- It is on a charger now and it should
rectify the problem. I was just concerned I had a bad relay or miss-wired s
omething.=C3=82=C2- The good news is I checked all my wiring Battery/ Alt
. switch etc.=C3=82=C2- They were all fine.
</blockquote>
=C2-=C2- . . . good connecting of the dots . . .
<blockquote>
I do have a basic question that I cannot seem to answer in my mind.=C3=82
=C2- When the Battery switch is on, there is power going to the alternato
r via the main B lead. Since that lead is connected directly to the output
side of the battery relay dose it not draw a significant amount of current
when the Battery master is on and the alternator is not running.=C3=82=C2
- In you book it show hat=C3=82=C2- lead connected to coils that are st
ationary in the alternator, then to ground believe.=C3=82=C2- My non elec
trical mind just cannot figure that out.
</blockquote>
=C2- An alternator generally has two connections
=C2- to the ship's electrical system. (1) The "B-Lead"
=C2- or battery lead that is a power-output connection
=C2- and an input lead that is (2a) excitation from the
=C2- regulator to the field . . .
http://www.aeroelectric.com/List_Files/Externally_Regulated-s.jpg
=C2-. . . or (2b) on/off control to the internal
=C2-regulator.
http://www.aeroelectric.com/List_Files/Internally_Regulated-s.jpg
=C2- In both cases, you can see that the B-lead
=C2- connects to the + side of a three-phase
=C2- rectifier . . . diodes that convert the
=C2- internally generated AC into DC while
=C2- preventing any back flow of current from
=C2- the battery into the alternator.
=C2- In all automotive applications, you will find that
=C2- the b-lead is always connected to the vehicle's
=C2- battery. The factory stock (+) battery cable for
=C2- my truck comes with two wires, a fat wire to the
=C2- starter solenoid and a not-so-fat wire running
=C2- directly to the alternator b-lead - power never
=C2- flows into this lead as long as the diodes
=C2- are intact.
=C2- The only 'input' lead to an externally regulated
=C2- alternator draws current when the alternator
=C2- control switch is ON. This is field current
=C2- from the regulator attempting to control
=C2- bus voltage. If the engine is not yet running,
=C2- the regulator will 'full field' the alternator
=C2- causing as much as 3 amps of draw on the
=C2- battery.
=C2- The modern internally regulated alternator
=C2- often features an integrated circuit that
=C2- 'watches' for the presence of ac voltage
=C2- from the stator windings. If no AC present
=C2- then the alternator is not rotating . . . and
=C2- field current is shut off. This prevents
=C2- the otherwise inevitable, non-productive
=C2- drain during times the engine is not running.
<blockquote>
It's been 5 years since I retired, but I do remember some screen interrupti
on, all be it small and fast during engine starts on some if not all the pl
anes I flew to make a buck.=C3=82=C2- Usually when changing from
APU power to the engine driven generators. =C3=82=C2- I guess its just pa
rt of the program
</blockquote>
=C2- Correct. This is a function of time-to-boot-up
=C2- inherent in the design of the appliance.
=C2- As I recall, all of the screens in the
=C2- line of Beech products pretty much came
=C2- alive in a second or less after application
=C2- of operating power whether first-on or
=C2- post brown-out . . . so we KNOW it can
=C2- be done. All of my software driven products
=C2- are wide-eyed, bright-eyed and bushy-tailed
=C2- milliseconds after power up.
=C2- But ever since the Blue Mountain days of
=C2- EFIS products offered to owner built and
=C2- maintained aircraft, there have be a variety
=C2- of instances where boot-up times were sometimes
=C2- distressingly long (Blue Mountain had a HARD
=C2- DRIVE!!). So not only did that product
=C2- need to load an operating system, it might
=C2- take many seconds after the software woke
=C2- up until the analog rate integration
=C2- calculations could get stood up in deducing
=C2- the gravity vector.
=C2- We've come a long way baby . . . but it's
=C2- still disappointing that some of the big
=C2- guns in the electronic instrumentation
=C2- business for light aircraft are not not
=C2- implementing the best we know how to do
=C2- in managing power-up/brown-outs events.
=C2- Bob . . .
=C2- Bob . . .
Message 5
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| Subject: | Re: Voltage drop |
At 11:18 AM 8/21/2016, you wrote:
>Hi Bob;
>Neat and very understandable schematics for externally and
>internally regulated alternators. Would you care to provide one for
>a internally regulated, permanent magnet alternator, so as to cover
>the subject exhaustively? I think I can deduce same, but would feel
>better to have it "from the horse's mouth."
>Cheers! Stu.
I'm not sure such a critter exitsts.
The only PM alternators I'm aware
of are exceedingly simple arrays of
magnets rotated about a stator winding
of suitable wire. Check out the images
at . . .
http://tinyurl.com/z27kpv4
These are PM alternators characteristic
of all such products from the lowly SD-8 up
through the 30A, 3-phase machines on some
small tractors.
Spinning magnets, stationary wires.
The energy coming out of these machines is
an AC current with frequency and voltage
proportional to engine RPM.
This is why the 'regulators' paired with
these devices are more properly called
RECTIFIER-REGULATORS.
They must not only convert the AC to DC
(like the diodes in the wound field
alternators) they must CONTROL that voltage
through devices that must CARRY the full
load current. Hence, there are no nifty,
itty-bitty regulators like those found in
wound field machines . . . instead, the R-R
is a rather robust device obviously designed
to dissipate HEAT.
It's a whole other breed of cat . . . so
sayeth the north end of the northbound
horse.
Bob . . .
Message 6
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| Subject: | EFIS Power Switch |
Folks,
I am reviewing my wiring diagrams, prior to starting to assemble the wiring
harness for my EFIS. I started with MGL's installation instructions, which
include an On/Off power switch for the whole MGL system: display + iBox +
RDAC + magnetometer + AHRS. You can see the "EFIS On-Off" switch in these
three diagrams:
=8B
can bus 1.pdf
<https://drive.google.com/a/zemon.name/file/d/0BzOP2gb9_3RQVU5TM3ktMy1tRDg/
view?usp=drive_web>
=8B=8B
can bus 2.pdf
<https://drive.google.com/a/zemon.name/file/d/0BzOP2gb9_3RQbFMzMFZ4S0tfbkU/
view?usp=drive_web>
=8B=8B
ibox.pdf
<https://drive.google.com/a/zemon.name/file/d/0BzOP2gb9_3RQeWx2MHBacWlQS2s/
view?usp=drive_web>
=8B
I am honestly not sure that I want this switch. Is there ever a time when I
would have the master switch on but not want power to the EFIS?
As far as current draining the battery, I am not too worried. The whole
system (all five components) draws just 1.7-2.9 amps, depending on display
brightness and whether or not the heaters in the magnetometer and AHRS are
energized.
-- Art Z.
--
http://CheerfulCurmudgeon.com/ <http://cheerfulcurmudgeon.com/>
*"If I am not for myself, who is for me? And if I am only for myself, what
am I? And if not now, when?" Hillel*
Message 7
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| Subject: | Re: Voltage drop |
Bob,
With respect to your 4th paragraph - I work in the TC maintenance side of th
e aviation industry, and have seen oil delivery system failure manifest itse
lf first during engine start. The majority of those times the failure was e
ither maintenance-induced or were on aircraft that have sat for extended per
iods with no attempt to pre-oil before starting (one of the bigger offenders
in the latter in my experience has been geared, turbocharged Continentals i
n Cessna 400 series aircraft, for some reason). A few, however were mechanic
al failures that were clued-in by oil pressure goofiness.
One of those involved a pipeline patrol aircraft whose operator said that he
didn't think the engine was developing full power. He also mentioned casual
ly that the oil pressure was jumping up high right away after engine start, a
nd had been doing that for several flights. That little tidbit led us to the
oil filter, which was chock full o metal bits. (After further clue-taking t
he engine was replaced...)
My take on this is that oil pressure behavior is one of several clues to eng
ine health. If the behavior departs from the norm then it's time to start as
king why. It's also the last chance you get to discover that after draining t
he oil for an oil change, you forgot to put oil back in - before it gets tur
ned into very expensive paper weights. It's why I'd recommend having some s
ort of backup for use during engine start or other times when the electrical
system has failed. In the TC world that's usually a backup battery (a la G
1000), but even a simple idiot light attached to an oil pressure switch woul
d help.
Chuck
On Aug 20, 2016, at 6:06 PM, Robert L. Nuckolls, III <nuckolls.bob@aeroelect
ric.com> wrote:
At 11:10 AM 8/20/2016, you wrote:
> The contactor normally gets a little warm--no worries there.=C3=82
>
> Your battery is probably just fine. My 925 does=C3=82 the same thing.=C3=82
>
> You'll need some kind of back-up battery to prevent what you're describing
. I use one from TCW that works great.
Oops . . . I stubbed my toe here. If you have any
electro-whizzies that reboot when presented with
a bus voltage below 11.0 volts . . . then they almost
certainly will reboot every time you start the engine.
I'm somewhat chagrined that folks who build and qualify
these panel mounted super-computers don't either (1)
study the real world of bus voltage behaviors during
engine start and/or (2) advise the customer that their
product WILL reboot during a start-up transient that
has ALWAYS existed on EVERY airplane.
To my mind, the simplest work-around is simply not to turn
on . . . or depend on these gizmos until after engine start.
Yeah, I know, our instructors taught us to concentrate on
the oil pressure display after engine start with a finger
on the mag switches lest the pressure not come up as expected.
But I would be interested to hear if anyone on this list
has ever experienced an failure of oil circulation that did
not manifest until right after start up. No doubt, Lindbergh
and contemporaries had good reason to worry about such things.
Those guys carried tool boxes around in the rear cockpit
with an eye toward needing off field maintenance of one
kind or another.
Now we have a new suite of technology which, for reasons
we'll never know, was NOT designed to replace
legacy instrumentation. DO-160 requires a qualified
product to (1) not be damaged by and (2) recover gracefully
from bus voltage brownouts quantified in the test
requirements document.
Problem is, graceful recovery has not been interpreted
to mean that the oil pressure display on the glass screen
needs to be as available and responsive as their steam
gage counterparts during the first few seconds after engine
start.
This leaves the system integrator (YOU) with a problem.
If you're going to pay homage to the legacy philosophy
for monitoring engine parameters that were of intense interest
to Charles Lindbergh, then we have to ADD power supply
brown-out buffers for these new electro-whizzies . . . that
COULD have been designed to accommodate such brown-outs.
The question becomes, are we adding cost, weight and complexity
to a system striving to honor a operating practice that
has been around since Lindbergh? What are the demonstrated
risks for cranking up an engine 'blind' an waiting for
the 'new' technology to wake up and report for duty?
Bob . . .
Message 8
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| Subject: | Re: Voltage drop |
At 03:24 PM 8/21/2016, you wrote:
>Bob,
>
>With respect to your 4th paragraph - I work in the TC maintenance
>side of the aviation industry, and have seen oil delivery system
>failure manifest itself first during engine start. The majority of
>those times the failure was either maintenance-induced or were on
>aircraft that have sat for extended periods with no attempt to
>pre-oil before starting (one of the bigger offenders in the latter
>in my experience has been geared, turbocharged Continentals in
>Cessna 400 series aircraft, for some reason). A few, however were
>mechanical failures that were clued-in by oil pressure goofiness.
Yes, aviation has been plagued with numerous
examples of engines that operated on the edge
of self destruction . . . the C175 engines
come to mind also. But again, what are the
probabilities that upon starting an engine
predominant in OBAM aviation aircraft that
it will present with a loss of oil pressure
. . . given that it taxied an airplane to
parking in the not too distant past?
Further, an aviation maintenance career
puts you in situations like doctors . . .
who never see anyone but sick people.
My last five years at Beech concentrated
on a series of seemingly intractable
difficulties . . . but for every airplane
I touched, there were thousands that did
not need or would benefit from my attention.
>My take on this is that oil pressure behavior is one of several
>clues to engine health. If the behavior departs from the norm then
>it's time to start asking why. It's also the last chance you get to
>discover that after draining the oil for an oil change, you forgot
>to put oil back in - before it gets turned into very expensive paper weights.
But do the FMEA on these hypothetical scenarios.
It's one thing that a particular engine/airframe
combination has a history of difficulties related
to loss of oil pressure . . . is anyone here on
the List flying such a machine? Forgetting to
put the oil in . . . any owner/op at elevated
risk for such errors has dozens of opportunities
for equal if not or more hazardous examples of
absent minded events.
If anyone is truly concerned about immediate
notification of oil pressure after start up,
I suggest that an oil pressure switch and
warning light would be a simpler, lower cost,
lighter weight and nearly zero maintenance
solution compared with any sort of battery
installation. Such switches are not subject
to the effects of brown-out.
Bob . . .
Message 9
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| Subject: | Re: Voltage drop |
Learned to fly a J3 with my Dad as the instructor. Even the old C65 was prone to
startup oil pressure issues. Had to watch carefully to see if pressure would
develop immediately after the hand prop. If not, you'd have to pull the pressure
line off the back of the pump and prime it with a squirt can so the gears
would have something to work with.
Jim Baker
405 426 5377
-----Original Message-----
From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
Sent: Sun, 21 Aug 2016 20:12
Subject: Re: AeroElectric-List: Voltage drop
--=====================_632832515==.ALT
Content-Type: text/plain; charset="us-ascii"; format=flowed
At 03:24 PM 8/21/2016, you wrote:
>Bob,
>
>With respect to your 4th paragraph - I work in the TC maintenance
>side of the aviation industry, and have seen oil delivery system
>failure manifest itself first during engine start. The majority of
>those times the failure was either maintenance-induced or were on
>aircraft that have sat for extended periods with no attempt to
>pre-oil before starting (one of the bigger offenders in the latter
>in my experience has been geared, turbocharged Continentals in
>Cessna 400 series aircraft, for some reason). A few, however were
>mechanical failures that were clued-in by oil pressure goofiness.
Yes, aviation has been plagued with numerous
examples of engines that operated on the edge
of self destruction . . . the C175 engines
come to mind also. But again, what are the
probabilities that upon starting an engine
predominant in OBAM aviation aircraft that
it will present with a loss of oil pressure
. . . given that it taxied an airplane to
parking in the not too distant past?
Further, an aviation maintenance career
puts you in situations like doctors . . .
who never see anyone but sick people.
My last five years at Beech concentrated
on a series of seemingly intractable
difficulties . . . but for every airplane
I touched, there were thousands that did
not need or would benefit from my attention.
>My take on this is that oil pressure behavior is one of several
>clues to engine health. If the behavior departs from the norm then
>it's time to start asking why. It's also the last chance you get to
>discover that after draining the oil for an oil change, you forgot
>to put oil back in - before it gets turned into very expensive paper weights.
But do the FMEA on these hypothetical scenarios.
It's one thing that a particular engine/airframe
combination has a history of difficulties related
to loss of oil pressure . . . is anyone here on
the List flying such a machine? Forgetting to
put the oil in . . . any owner/op at elevated
risk for such errors has dozens of opportunities
for equal if not or more hazardous examples of
absent minded events.
If anyone is truly concerned about immediate
notification of oil pressure after start up,
I suggest that an oil pressure switch and
warning light would be a simpler, lower cost,
lighter weight and nearly zero maintenance
solution compared with any sort of battery
installation. Such switches are not subject
to the effects of brown-out.
Bob . . .
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Content-Type: text/html; charset="us-ascii"
<html>
<body>
<font size=3>At 03:24 PM 8/21/2016, you wrote:<br>
<blockquote type=cite class=cite cite="">Bob, <br><br>
With respect to your 4th paragraph - I work in the TC maintenance side of
the aviation industry, and have seen oil delivery system failure manifest
itself first during engine start. The majority of those times the
failure was either maintenance-induced or were on aircraft that have sat
for extended periods with no attempt to pre-oil before starting (one of
the bigger offenders in the latter in my experience has been geared,
turbocharged Continentals in Cessna 400 series aircraft, for some
reason). A few, however were mechanical failures that were clued-in by
oil pressure goofiness.</font></blockquote>
<dl>
<dd>Yes, aviation has been plagued with numerous
<dd>examples of engines that operated on the edge
<dd>of self destruction . . . the C175 engines
<dd>come to mind also. But again, what are the
<dd>probabilities that upon starting an engine
<dd>predominant in OBAM aviation aircraft that
<dd>it will present with a loss of oil pressure
<dd> . . . given that it taxied an airplane to
<dd>parking in the not too distant past?<br><br>
<dd>Further, an aviation maintenance career
<dd>puts you in situations like doctors . . .
<dd>who never see anyone but sick people.
<dd>My last five years at Beech concentrated
<dd>on a series of seemingly intractable
<dd>difficulties . . . but for every airplane
<dd>I touched, there were thousands that did
<dd>not need or would benefit from my
attention.<br><br><blockquote type=cite class=cite cite="">
</dl><font size=3>My take on this is that oil pressure behavior is one of
several clues to engine health. If the behavior departs from the norm
then it's time to start asking why. It's also the last chance you get to
discover that after draining the oil for an oil change, you forgot to put
oil back in - before it gets turned into very expensive paper
weights.</font></blockquote>
<dl>
<dd>But do the FMEA on these hypothetical scenarios.
<dd>It's one thing that a particular engine/airframe
<dd>combination has a history of difficulties related
<dd>to loss of oil pressure . . . is anyone here on
<dd>the List flying such a machine? Forgetting to
<dd>put the oil in . . . any owner/op at elevated
<dd>risk for such errors has dozens of opportunities
<dd>for equal if not or more hazardous examples of
<dd>absent minded events.<br><br>
<dd>If anyone is truly concerned about immediate
<dd>notification of oil pressure after start up,
<dd>I suggest that an oil pressure switch and
<dd>warning light would be a simpler, lower cost,
<dd>lighter weight and nearly zero maintenance
<dd>solution compared with any sort of battery
<dd>installation. Such switches are not subject
<dd>to the effects of brown-out.<br>
<br><br><x-sigsep><p></x-sigsep>
</dl><font size=3> Bob . . .</font>
--=====================_632832515==.ALT--
</b></font></pre>
--=====================_632832515==.ALT--
Message 10
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| Subject: | Re: Voltage drop |
Hi Bob;
One such critter is DB Electrical APM0009, which is a 12 V., 20 Amp, intern
ally regulated permanent magnet alternator.
Cheers!=C2-=C2- Stu.
----- Original Message -----
From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
Sent: Sunday, August 21, 2016 11:17:35 AM
Subject: Re: AeroElectric-List: Voltage drop
At 11:18 AM 8/21/2016, you wrote:
Hi Bob;
Neat and very understandable schematics for externally and internally regul
ated alternators. Would you care to provide one for a internally regulated,
permanent magnet alternator, so as to cover the subject exhaustively? I th
ink I can deduce same, but would feel better to have it "from the horse's m
outh."
Cheers!=C2-=C2- Stu.
=C2-=C2- I'm not sure such a critter exitsts.
=C2-=C2- The only PM alternators I'm aware
=C2-=C2- of are exceedingly simple arrays of
=C2-=C2- magnets rotated about a stator winding
=C2-=C2- of suitable wire. Check out the images
=C2-=C2- at . . .
http://tinyurl.com/z27kpv4
=C2-=C2- These are PM alternators characteristic
=C2-=C2- of all such products from the lowly SD-8 up
=C2-=C2- through the 30A, 3-phase machines on some
=C2-=C2- small tractors.
=C2-=C2- Spinning magnets, stationary wires.
=C2-=C2- The energy coming out of these machines is
=C2-=C2- an AC current with frequency and voltage
=C2-=C2- proportional to engine RPM.
=C2-=C2- This is why the 'regulators' paired with
=C2-=C2- these devices are more properly called
=C2-=C2- RECTIFIER-REGULATORS.
=C2-=C2- They must not only convert the AC to DC
=C2-=C2- (like the diodes in the wound field
=C2-=C2- alternators) they must CONTROL that voltage
=C2-=C2- through devices that must CARRY the full
=C2-=C2- load current. Hence, there are no nifty,
=C2-=C2- itty-bitty regulators like those found in
=C2-=C2- wound field machines . . . instead, the R-R
=C2-=C2- is a rather robust device obviously designed
=C2-=C2- to dissipate HEAT.
=C2-=C2- It's a whole other breed of cat . . . so
=C2-=C2- sayeth the north end of the northbound
=C2-=C2- horse.=C2-=C2-=C2-=C2-=C2-=C2-=C2- =C2-=C2-
=C2-=C2-=C2-=C2-=C2-=C2-
=C2- Bob . . .
Message 11
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| Subject: | Re: EFIS Power Switch |
> I am honestly not sure that I want this switch. Is there ever a time when I would
have the master switch on but not want power to the EFIS?
The pilot should have the ability to shut off each and every electrical load.
If the MGL units have their own switches, than an additional switch is not necessary.
If the MGL malfunctions or gives off smoke, there should be a way to
shut it off without shutting off everything else.
On the other hand, if you do not mind shutting off the master switch if necessary,
it is not a big deal. Builders of experimental aircraft can wire the airplane
to meet their goals. As long as it is not dangerous, do it the way you
want.
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=459733#459733
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