Today's Message Index:
----------------------
1. 05:40 AM - Re: testing of backup alternator (Ken)
2. 06:38 AM - Re: Z-12 questions (Robert L. Nuckolls, III)
3. 07:01 AM - Re: testing of backup alternator (Robert L. Nuckolls, III)
4. 07:35 AM - Re: testing of backup alternator ()
5. 07:53 AM - Re: testing of backup alternator (Dj Merrill)
6. 08:32 AM - Re: testing of backup alternator (Ken)
7. 08:40 AM - Re: GPS outage in fiberglass plane (Radioflyer)
8. 08:53 AM - Re: Re: GPS outage in fiberglass plane (James Kilford)
9. 09:40 AM - Re: Z-12 questions (corrections) (Robert L. Nuckolls, III)
10. 07:12 PM - Re: GRT EIS-Fuel Sender (jonlaury)
11. 07:25 PM - Re: Re: GRT EIS-Fuel Sender (John Grosse)
Message 1
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Subject: | Re: testing of backup alternator |
I definitely failed a John Deere PM regulator just by starting the
engine on the ground with a totally dead battery. An immediate over
voltage caused the crowbar OV module to trip the AC relay off, and the
regulator evermore put out max voltage after the battery was recharged.
I never have had a large capacitor in that system which might have
helped. It was a sealed battery and they don't accept current for some
time (if ever) when totally discharged. Undoubtedly the same failure
would occur with a disconnected battery.
Ken
Robert L. Nuckolls, III wrote:
> <nuckolls.bob@aeroelectric.com>
>
> At 03:15 PM 8/26/2010, you wrote:
>>
>> On 08/26/2010 03:17 PM, longg@pjm.com wrote:
>> > From what
>> > I understand it's not recommended to re-start some of these alternators
>> > in flight. It may blow off the cowling and your firewall may melt.
>>
>>
>> Would absolutely love to see some real data to back up this
>> claim...
>> Can you point us to any references?
>
> I've been testing alternators and generators on airplanes,
> laboratory test stands and an odd assortment of vehicles
> for 40+ years. We turn them on, off, no-load, full-load,
> you name it. Whether or not there's a battery on line.
> See chapter on engine driven power sources in:
>
> http://www.aeroelectric.com/Book/AEC12A_PDF.zip
>
> Having said that, there MAY be regulator characteristics
> (whether internal in or external) that present poor transient
> response without a battery on line. Indeed, this is one
> of the situations described by "load dump" in automotive
> parlance and "battery dump" in aviation parlance. Depending
> on how wildly the system behaves without a battery, SOME
> devices may be at risk if they're tied to the bus. This
> INCLUDES poorly designed regulators. This was the problem
> reported but not understood a few years back when some
> folks experienced alternator/regulator damage when switching
> a Z-24 system off with the alternator loaded. However,
> this is the exception.
>
> Bottom line is, as long as the battery stays tied to the
> alternator's b-lead, there's nothing you can do with
> switches on the panel that will hurt anything . . .
>
> In other words, transients generated by such activities
> do not exceed NORMAL operating transients as described
> in Mil-STD-704 and DO-160. Even with Z-24 configuration,
> an internally regulated alternator worth your hard-earned
> dollars is not at-risk for inadvertent switch positioning.
>
> Bob . . .
>
>
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Subject: | Re: Z-12 questions |
At 11:52 PM 8/26/2010, you wrote:
>Bob,
>
>I know you're a very busy man, so I hope I'm not imposing too much
>by asking you a couple of questions. I'm hoping you can help shed
>some light on these issues, for which I've been unable to find answers:
No problem, it's what we do.
>
>1. My RV-8 will utilize a Z-12-based architecture, including a 60A
>main alternator, and a 20A backup alternator from B&C mounted on the
>vacuum pad. I am using the standard LR-3 and SB-1 alternator
>controllers. My first question is: Does the "Aux Alternator" switch
>normally stay ON during flight, so that the Aux alternator actually
>provides power to the Main Bus all the time? Or should the switch
>stay OFF, only to be switched on by the pilot in the event of a Main
>alternator failure?
The SB-1 alternator is specifically designed for STANDBY service
and is normally installed with a setpoint down around 13.5 volts.
Therefore, the second alternator installed for standby service is
not intended to either share loads with the main alternator nor
is it intended to charge the ship's battery.
It's your option, you can leave it ON or OFF at all times for normal
flight . . . if left ON, the SB-1 regulator will interpret the
normal bus voltage of 14+ volts as "too high" and will completely
relax thus driving the SB alternator field voltage to zero.
In the event of main alternator shut down for any reason, the
bus voltage would normally fall to battery support levels
that start at about 12.5 volts and goes down from there.
If the SB alternator is ON, this depression in bus votlage
will cause the SB-1 regulator to wake up and bring the
standby alternator into service. It will annunciate the fact
by illuminating the SB ALT loaded light. If total loads on
the SB alternator exceed 20A, the SB-1 will flash the warning
light . . . the pilot is advised to reduce ship's electrical
loads until flashing stops.
If left OFF, you'll get a LO VOLTS warning light that
prompts you to turn the sb alternator ON and
then do the load-shedding exercise.
>
>2. My interpretation of the Z-12 architecture indicates that in the
>event of a Main alternator failure, it would be the pilot's job to
>manually load-shed the electrical system so that the total load was
>below 20A. This is because the Aux alternator would feed the Main
>Bus (and thence the Endurance Bus), so in the event of an Aux
>alternator-only operation, most of the Main Bus items would have to
>be turned off (or not used). My Endurance Bus will pull about 10A,
>so I'd like to feed the Endurance Bus directly from the Aux
>alternator (in addition to the normal feed path from the Main Bus).
>That way, I could perform a quick, pre-selected load-shed operation
>merely by turning off the Main Alternator switch and turning on the
>Aux Alternator switch. (And, of course, I'd also have the E-Bus
>Alternate feed from the Batt Bus, as a last-ditch backup.) So my
>second question is: Is this a reasonable modification to the Z-12
>architecture? My goal is a simple, robust system, but I'd like the
>convenience and pilot friendliness of a dirt-simple "load shed"
>procedure, rather than a manual load-shed -- and having to ration
>power to the Main Bus items.
Then you're not talking about Z-12 (originally crafted to
be a drop-in for type certificated aircraft that (1) doesn't
have an e-bus and (2) would be exceedingly difficult under
FAA rules to shuffle bus structures around. The system you're
describing looks more like this
http://tinyurl.com/24j8gh4
This is a more robust version of Z-13/8 where the 20A
alternator is installed primarily to support an electrically
dependent engine. No e-bus is shown because if you have
a robust second alternator, there's no likelihood of needing
to operate battery-only . . . that's two major failures on
a single tank of fuel. Hence the simple direct connection
for the sb alternator to the battery such that battery
contactor failures are covered.
"Last ditch" ???? You're spending too much time worrying
about things that only happen in Hollywood's notions of
how airplanes work. Modern alternators properly integrated
into your airplane are very low failure rate items.
It is unlikely that you will EVER find experience a
pressing need to drop to SB alternator or a battery-only
ops mode over the lifetime of your airplane. In 25 years
of working with the OBAM aviation community, I've had
but a handful of readers report that the s/b alternator
or e-bus ops were found useful and functioned as advertised.
If the airplane you're flying now is a TC aircraft, then
it has no e-bus, no sb alternator, might even be a rented
airplane where you have little knowledge of and zero
control over ship's maintenance. This has always been
my personal situation having never owned an airplane.
So when I walk up to the airplane, I do it with the
mind set that I don't care if the electrical system
is going to work 100.0% of the time or not. I've got
stuff in my flight bag that will allow me to operate
any of the airplanes I fly in "J-3 mode" with a goal
of aviating to airport of intended destination whether
or not anything on the panel works.
http://aeroelectric.com/Pictures/Misc/Failure_Tolerance.pdf
No matter what electrical system is installed in your
OBAM aircraft, the stuff in your flight bag should be
similarly selected. If you've got smelly stuff in the
cockpit that's suspiciously like wire or electrical
accessory smoke, you might just want to shut everything
off, dig out the REAL stand-by goodies and keep on truck'n.
Actually, I've not turned a panel mounted nav radio
on since I purchased my first hand-held GPS in '95.
The $100 Magellans do 99% of everything I need the
nav radio to do . . . how far, which direction,
and ETA.
Your questions give the distinct impression that
you don't have much trust in the hardware for which
you're crafting an architecture. Lack of trust comes
from some combination of three conditions:
(1) You KNOW you're installing certified junk on
an airplane constrained by regulation to be forever
less than the best we know how to do.
(2) You don't personally possess a demonstrable,
experience-based data set the confirms the reliability
enjoyed by the OBAM aircraft community.
(3) Your understanding of the system is diluted
with a lot of extraneous noise exemplified by the
majority of dark-n-stormy-night stories in the
flying rags and the nail-biter scenarios dreamed
up by Hollywood writers to make the actors look
like the gods of failure mitigation.
If you're crafting an airplane with an electrically
dependent engine where all the engine support
comes from the battery bus, then Z-08 is recommended.
If your engine is not electrically dependent
then Z-12 as depicted is recommended.
When and if that low voltage warning light ever
comes on, know that this is NOT an emergency
You can finish your cup of coffee and decide
what, if anything, you plan to do about it.
The point is, there IS A PLAN that probably
requires repositioning less than a half dozen
switches until the light stops flashing.
Hence, I'll suggest that your quest for "dirt
simple" responses to a "last ditch" scenario
are probably not a good investment of emotional
capital or time.
You need to tell us more about what equipment
is installed on what kind of engine for the
advice to me more specific.
Bob . . .
Message 3
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Subject: | Re: testing of backup alternator |
At 07:28 AM 8/27/2010, you wrote:
>
>I definitely failed a John Deere PM regulator just by starting the
>engine on the ground with a totally dead battery.
>An immediate over voltage caused the crowbar OV module to trip the
>AC relay off,
Hmmm . . . It may be that the JD rectifier/regulator
has some feature a bit short on robustness . . . but
the scenario you describe is not one that immediately
suggests this. It's a certainty that yard maintenance
equipment is quite often jump-started into a dead battery.
>and the regulator evermore put out max voltage after the battery was
>recharged.
This my have been an isolated failure. Have you replaced
the r/r and found that everything works as expected?
>I never have had a large capacitor in that system which might have helped.
This would not have made any difference.
>It was a sealed battery and they don't accept current for some time
>(if ever) when totally discharged. Undoubtedly the same failure
>would occur with a disconnected battery.
Maybe, but does the owner's manual for any item
of JD equipment caution against operations with
a completely discharged but otherwise good battery?
I'm not sure you have enough data about the
manufacturer's design goals to arrive at this
conclusion. Certainly the scenario you describe
happens many times on perhaps thousands of mowers
and tractors every summer . . . if they were blowing
up R/R like popcorn, I have to believe there would
be some scrambling around in the JD engineering
community to fix it.
Obviously, my earlier comment to this thread
pertained only to wound-field alternators. The
permanent magnet devices with rectifier/regulators
are another breed of cat.
Bob . . .
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Subject: | testing of backup alternator |
DJ,
I do not but, based on Bob's generally reliable response I don't have to
worry about pilot tales to complete my testing. As Bob indicated unless
the battery is completely dead (not gonna happen in my case -on purpose
- caus' the Lightspeed requires min 5 volts to run), I can safely switch
on and off. That gives me the added comfort of continuing my flight say
if the alt CB pops momentarily and I want to turn off the Alt to reset
it. Naturally I'll only do that once in unknown circumstances.
In most cases I could run a very long distance with the SD-8.
One easy way to provide proof for yourself is to go out and do the
tests. If so worried, turn off everything else first. If you don't know
the limits of your machine, you don't know your machine.
I'll be out testing.
Glenn E. Long
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Dj
Merrill
Sent: Thursday, August 26, 2010 4:15 PM
Subject: Re: AeroElectric-List: testing of backup alternator
On 08/26/2010 03:17 PM, longg@pjm.com wrote:
> From what
> I understand it's not recommended to re-start some of these
alternators
> in flight. It may blow off the cowling and your firewall may melt.
Would absolutely love to see some real data to back up this
claim...
Can you point us to any references?
Thanks,
-Dj
--
Dj Merrill - N1JOV
Glastar Sportsman 2+2 Builder #7118 N421DJ - http://deej.net/sportsman/
Grumman Yankee Driver N9870L - http://deej.net/yankee/
Join us on the New England Aviation Forums - http://forum.deej.net/
Message 5
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Subject: | Re: testing of backup alternator |
On 08/27/2010 10:31 AM, longg@pjm.com wrote:
> One easy way to provide proof for yourself is to go out and do the
> tests. If so worried, turn off everything else first. If you don't know
> the limits of your machine, you don't know your machine.
Hi Glenn,
I've turned on and off the alternator with the engine running many
times without incident. In particular, I was taking mild exception with
your statements:
>> From what
>> I understand it's not recommended to re-start some of these
> alternators
>> in flight. It may blow off the cowling and your firewall may melt.
which I do not believe are true, and was asking if there were any
references where this had actually happened. I've certainly never heard
of a cowling blowing off nor a firewall melting due to someone turning
on their alternator... :-)
Could be you were trying to be sarcastic, in which case I was hoping no
one was actually thinking you were serious, and wanted to attempt to
stop more Old Wives Tales on this topic... :-)
Thanks,
-Dj
--
Dj Merrill - N1JOV
Glastar Sportsman 2+2 Builder #7118 N421DJ - http://deej.net/sportsman/
Grumman Yankee Driver N9870L - http://deej.net/yankee/
Join us on the New England Aviation Forums - http://forum.deej.net/
Message 6
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Subject: | Re: testing of backup alternator |
Yes a replacement regulator has worked perfectly for several hundred
hours. You make a good point about the lawn equipment and dead
batteries so maybe it was a one off failure. From what I've seen over
the years though I think a dead flooded cell battery (as found in all
the lawn equipment that I've seen) might have absorbed enough current to
prevent the failure. So my theory is that the sealed AGM battery was
the critical factor. It was a totally discharged battery. Anyway thought
it might save someone a hundred dollars and some hassle to mention my
experience.
Ken
Robert L. Nuckolls, III wrote:
> <nuckolls.bob@aeroelectric.com>
>
> At 07:28 AM 8/27/2010, you wrote:
>>
>> I definitely failed a John Deere PM regulator just by starting the
>> engine on the ground with a totally dead battery.
>> An immediate over voltage caused the crowbar OV module to trip the AC
>> relay off,
>
> Hmmm . . . It may be that the JD rectifier/regulator
> has some feature a bit short on robustness . . . but
> the scenario you describe is not one that immediately
> suggests this. It's a certainty that yard maintenance
> equipment is quite often jump-started into a dead battery.
>
>
>> and the regulator evermore put out max voltage after the battery was
>> recharged.
>
> This my have been an isolated failure. Have you replaced
> the r/r and found that everything works as expected?
>
>> I never have had a large capacitor in that system which might have
>> helped.
>
> This would not have made any difference.
>
>> It was a sealed battery and they don't accept current for some time
>> (if ever) when totally discharged. Undoubtedly the same failure would
>> occur with a disconnected battery.
>
> Maybe, but does the owner's manual for any item
> of JD equipment caution against operations with
> a completely discharged but otherwise good battery?
> I'm not sure you have enough data about the
> manufacturer's design goals to arrive at this
> conclusion. Certainly the scenario you describe
> happens many times on perhaps thousands of mowers
> and tractors every summer . . . if they were blowing
> up R/R like popcorn, I have to believe there would
> be some scrambling around in the JD engineering
> community to fix it.
>
> Obviously, my earlier comment to this thread
> pertained only to wound-field alternators. The
> permanent magnet devices with rectifier/regulators
> are another breed of cat.
>
>
> Bob . . .
>
>
>
>
Message 7
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Subject: | Re: GPS outage in fiberglass plane |
This has been an interesting discussion to read through. I've had similar experiences
with a Garmin 296 that had me baffled for a while. I first used my unit
extensively on a Florida to Boston cross country flight in a LongEZ. Maybe I
experienced a very brief lost of signal, but it was of no consequence. The unit
provided excellent service.
Then I started using it in a C172 and noticed a troubling occurence of dropouts.
Tried new software, and different antenna. Eventually, I got to associate the
dropouts with specific routes, some of which had known large ground antenna
installations, so I thought it was just groundstation intereference. But no one
I talked to seem to be experiencing GPS problems in the area. I have used the
unit in another Cessna and while the dropouts were not at all as frequent, they
still occurred unpredictably. I had lost faith in my GPS.
I had learned from various sources that the navcoms could jam the GPS. So after
reading this thread, I finally took the time to check this out. I had just come
back from a flight during which the GPS performed flawlessly. While on the
tiedown, with engine and everything running, I started to tune in the various
com frequencies I use in my area. With the GPS screen set to show the sat reception
bars, I quickly found that the bars would quickly pulse down to nothing
when the frequency was set between 119.200 to 119.5. This was even without transmitting
and it was dramatic. As it turns out, I am usually tuned within this
frequency range when flying the routes I had associated with GPS loss.
Since the G296 seems to work well in the LongEz, but with dropouts in the Cessna,
the problem is with the Cessna radio and not the GPS. Not surprisingly, different
radio installations have different RF signatures and tolerances. Maybe
the Cessna radio is out of spec, maybe not, but it is good to know finally, what
is causing my dropouts. Now if I'm lost and the GPS drops out, I know I can
change frequencies or turn off the avionics and get re-oriented.
--Jose
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=310285#310285
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Subject: | Re: GPS outage in fiberglass plane |
Interesting stuff. That's worth everyone with a GPS tucking away in
the "for future reference" part of the brain. Thanks for taking the
time to report this info.
James
On Fri, Aug 27, 2010 at 4:39 PM, Radioflyer <skyeyecorp@airpost.net> wrote:
>
> This has been an interesting discussion to read through. I've had similar experiences
with a Garmin 296 that had me baffled for a while. I first used my unit
extensively on a Florida to Boston cross country flight in a LongEZ. Maybe
I experienced a very brief lost of signal, but it was of no consequence. The unit
provided excellent service.
>
> Then I started using it in a C172 and noticed a troubling occurence of dropouts.
Tried new software, and different antenna. Eventually, I got to associate
the dropouts with specific routes, some of which had known large ground antenna
installations, so I thought it was just groundstation intereference. But no
one I talked to seem to be experiencing GPS problems in the area. I have used
the unit in another Cessna and while the dropouts were not at all as frequent,
they still occurred unpredictably. I had lost faith in my GPS.
>
> I had learned from various sources that the navcoms could jam the GPS. So after
reading this thread, I finally took the time to check this out. I had just
come back from a flight during which the GPS performed flawlessly. While on the
tiedown, with engine and everything running, I started to tune in the various
com frequencies I use in my area. With the GPS screen set to show the sat reception
bars, I quickly found that the bars would quickly pulse down to nothing
when the frequency was set between 119.200 to 119.5. This was even without transmitting
and it was dramatic. As it turns out, I am usually tuned within this
frequency range when flying the routes I had associated with GPS loss.
>
> Since the G296 seems to work well in the LongEz, but with dropouts in the Cessna,
the problem is with the Cessna radio and not the GPS. Not surprisingly, different
radio installations have different RF signatures and tolerances. Maybe
the Cessna radio is out of spec, maybe not, but it is good to know finally,
what is causing my dropouts. Now if I'm lost and the GPS drops out, I know I can
change frequencies or turn off the avionics and get re-oriented.
>
> --Jose
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=310285#310285
>
>
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Subject: | Re: Z-12 questions (corrections) |
At 08:38 AM 8/27/2010, you wrote:
>At 11:52 PM 8/26/2010, you wrote:
>>Bob,
>>
>>I know you're a very busy man, so I hope I'm not imposing too much
>>by asking you a couple of questions. I'm hoping you can help shed
>>some light on these issues, for which I've been unable to find answers:
>
> No problem, it's what we do.
>>
>>1. My RV-8 will utilize a Z-12-based architecture, including a 60A
>>main alternator, and a 20A backup alternator from B&C mounted on
>>the vacuum pad. I am using the standard LR-3 and SB-1 alternator
>>controllers. My first question is: Does the "Aux Alternator" switch
>>normally stay ON during flight, so that the Aux alternator actually
>>provides power to the Main Bus all the time? Or should the switch
>>stay OFF, only to be switched on by the pilot in the event of a
>>Main alternator failure?
>
> The SB-1 REGULATOR is specifically designed for STANDBY service
> and is normally installed with a setpoint down around 13.5 volts.
> Therefore, the second alternator installed for standby service
USING THE SB-1 is not intended to either share loads with the main
alternator nor is it intended to charge the ship's battery.
> It's your option, you can leave it ON or OFF at all times for normal
> flight . . . if left ON, the SB-1 regulator will interpret the
> normal bus voltage of 14+ volts as "too high" and will completely
> relax thus driving the SB alternator field voltage to zero.
>
> In the event of main alternator shut down for any reason, the
> bus voltage would normally fall to battery support levels
> that start at about 12.5 volts and goes down from there.
> If the SB alternator is ON, this depression in bus votlage
> will cause the SB-1 regulator to wake up and bring the
> standby alternator into service. It will annunciate the fact
> by illuminating the SB ALT loaded light. If total loads on
> the SB alternator exceed 20A, the SB-1 will flash the warning
> light . . . the pilot is advised to reduce ship's electrical
> loads until flashing stops.
>
> If left OFF, you'll get a LO VOLTS warning light that
> prompts you to turn the sb alternator ON and
> then do the load-shedding exercise.
ONE COULD RAISE THE SET-POINT ON AN SB-1 TO 14.4
VOLTS WHEREUPON IT WOULD BE CAPABLE OF BATTERY
MAINTENANCE. IN THIS CASE, YOU WOULD LEAVE THE
AUX ALTERNATOR OFF FOR NORMAL FLIGHT, TURN ON ONLY
AFTER AN LV WARNING PROMPTED YOU. Y0U WOULD STILL
HAVE THE AID FOR LOAD SHEDDING . . . YOU ONLY
GIVE UP THE AUTO-SWITCHING FEATURE THE SB-1 WAS
DESIGNED TO SUPPORT.
>>
>>2. My interpretation of the Z-12 architecture indicates that in the
>>event of a Main alternator failure, it would be the pilot's job to
>>manually load-shed the electrical system so that the total load was
>>below 20A. This is because the Aux alternator would feed the Main
>>Bus (and thence the Endurance Bus), so in the event of an Aux
>>alternator-only operation, most of the Main Bus items would have to
>>be turned off (or not used). My Endurance Bus will pull about 10A,
>>so I'd like to feed the Endurance Bus directly from the Aux
>>alternator (in addition to the normal feed path from the Main Bus).
>>That way, I could perform a quick, pre-selected load-shed operation
>>merely by turning off the Main Alternator switch and turning on the
>>Aux Alternator switch. (And, of course, I'd also have the E-Bus
>>Alternate feed from the Batt Bus, as a last-ditch backup.) So my
>>second question is: Is this a reasonable modification to the Z-12
>>architecture? My goal is a simple, robust system, but I'd like the
>>convenience and pilot friendliness of a dirt-simple "load shed"
>>procedure, rather than a manual load-shed -- and having to ration
>>power to the Main Bus items.
>
> Then you're not talking about Z-12 (originally crafted to
> be a drop-in for type certificated aircraft that (1) doesn't
> have an e-bus and (2) would be exceedingly difficult under
> FAA rules to shuffle bus structures around. The system you're
> describing looks more like this
>
>http://tinyurl.com/24j8gh4
>
> This is a more robust version of Z-13/8 where the 20A
> alternator is installed primarily to support an electrically
> dependent engine. No e-bus is shown because if you have
> a robust second alternator, there's no likelihood of needing
> to operate battery-only . . . that's two major failures on
> a single tank of fuel. Hence the simple direct connection
> for the sb alternator to the battery such that battery
> contactor failures are covered.
>
> "Last ditch" ???? You're spending too much time worrying
> about things that only happen in Hollywood's notions of
> how airplanes work. Modern alternators properly integrated
> into your airplane are very low failure rate items.
>
> It is unlikely that you will EVER find experience a
> pressing need to drop to SB alternator or a battery-only
> ops mode over the lifetime of your airplane. In 25 years
> of working with the OBAM aviation community, I've had
> but a handful of readers report that the s/b alternator
> or e-bus ops were found useful and functioned as advertised.
>
> If the airplane you're flying now is a TC aircraft, then
> it has no e-bus, no sb alternator, might even be a rented
> airplane where you have little knowledge of and zero
> control over ship's maintenance. This has always been
> my personal situation having never owned an airplane.
>
> So when I walk up to the airplane, I do it with the
> mind set that I don't care if the electrical system
> is going to work 100.0% of the time or not. I've got
> stuff in my flight bag that will allow me to operate
> any of the airplanes I fly in "J-3 mode" with a goal
> of aviating to airport of intended destination whether
> or not anything on the panel works.
>
>http://aeroelectric.com/Pictures/Misc/Failure_Tolerance.pdf
>
> No matter what electrical system is installed in your
> OBAM aircraft, the stuff in your flight bag should be
> similarly selected. If you've got smelly stuff in the
> cockpit that's suspiciously like wire or electrical
> accessory smoke, you might just want to shut everything
> off, dig out the REAL stand-by goodies and keep on truck'n.
>
> Actually, I've not turned a panel mounted nav radio
> on since I purchased my first hand-held GPS in '95.
> The $100 Magellans do 99% of everything I need the
> nav radio to do . . . how far, which direction,
> and ETA.
>
> Your questions give the distinct impression that
> you don't have much trust in the hardware for which
> you're crafting an architecture. Lack of trust comes
> from some combination of three conditions:
>
> (1) You KNOW you're installing certified junk on
> an airplane constrained by regulation to be forever
> less than the best we know how to do.
>
> (2) You don't personally possess a demonstrable,
> experience-based data set the confirms the reliability
> enjoyed by the OBAM aircraft community.
>
> (3) Your understanding of the system is diluted
> with a lot of extraneous noise exemplified by the
> majority of dark-n-stormy-night stories in the
> flying rags and the nail-biter scenarios dreamed
> up by Hollywood writers to make the actors look
> like the gods of failure mitigation.
>
> If you're crafting an airplane with an electrically
> dependent engine where all the engine support
> comes from the battery bus, then Z-08 is recommended.
> If your engine is not electrically dependent
> then Z-12 as depicted is recommended.
>
> When and if that low voltage warning light ever
> comes on, know that this is NOT an emergency
> You can finish your cup of coffee and decide
> what, if anything, you plan to do about it.
> The point is, there IS A PLAN that probably
> requires repositioning less than a half dozen
> switches until the light stops flashing.
>
> Hence, I'll suggest that your quest for "dirt
> simple" responses to a "last ditch" scenario
> are probably not a good investment of emotional
> capital or time.
>
> You need to tell us more about what equipment
> is installed on what kind of engine for the
> advice to me more specific.
>
> Bob . . .
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Subject: | Re: GRT EIS-Fuel Sender |
Bob, you said:
> That "unusable fuel" has two important functions.
> (1) provide a low-spot for moisture collection
> and (2) keep the vapor in the tank saturated.
I spent a lot of time and effort to make sure that every drop in my fuel tanks
was usable except for the debris sumps. The mains and header can be pumped dry
except for sump fuel (4-6 ounces).
Is the small amount of fuel in the sumps enough to keep a 12' long wing tank vapor-saturated?
I wasn't ever worried about this before, but now that it's out on the line, just
want to be sure I'm not committing a major oversight.
J
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=310335#310335
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Subject: | Re: GRT EIS-Fuel Sender |
You don't have to run the tanks dry.
John Grosse
jonlaury wrote:
> --> AeroElectric-List message posted by: "jonlaury"<jonlaury@impulse.net>
>
> Bob, you said:
>
>
>> That "unusable fuel" has two important functions.
>> (1) provide a low-spot for moisture collection
>> and (2) keep the vapor in the tank saturated.
>>
>
>
> I spent a lot of time and effort to make sure that every drop in my fuel tanks
was usable except for the debris sumps. The mains and header can be pumped dry
except for sump fuel (4-6 ounces).
>
> Is the small amount of fuel in the sumps enough to keep a 12' long wing tank
vapor-saturated?
>
> I wasn't ever worried about this before, but now that it's out on the line, just
want to be sure I'm not committing a major oversight.
>
> J
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=310335#310335
>
>
>
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