Today's Message Index:
----------------------
1. 04:14 AM - Re: Re: Transponder antenna location (FLYaDIVE@aol.com)
2. 04:35 AM - Re: Alternator Problem - Not in plane (FLYaDIVE@aol.com)
3. 04:42 AM - Re: Fuel Pump Switch(es) (FLYaDIVE@aol.com)
4. 04:57 AM - Re: Switch contact rattings which is best for this app (FLYaDIVE@aol.com)
5. 05:38 AM - Re: Re: John Deere PM alternator regulator (Ken)
6. 05:59 AM - Glowing Warning Lights (MikeEasley@aol.com)
7. 06:28 AM - Re: Re: John Deere PM alternator regulator (Dave N6030X)
8. 07:00 AM - Fuel Pump Switch(es) (glen matejcek)
9. 07:13 AM - Engine analyzer OFF for engine start? (Kelly McMullen)
10. 07:49 AM - Re: Glowing Warning Lights (Matt Prather)
11. 07:55 AM - the George debate (Fergus Kyle)
12. 08:46 AM - Re: Re: Transponder antenna location (Robert L. Nuckolls, III)
13. 10:37 AM - Re: Glowing Warning Lights (Robert L. Nuckolls, III)
14. 10:51 AM - Re: Engine analyzer OFF for engine start? (Robert L. Nuckolls, III)
15. 10:59 AM - Re: Fuel Pump Switch(es) (Brian Lloyd)
16. 11:06 AM - Re: Switch Ratings (Robert L. Nuckolls, III)
17. 11:07 AM - Re: Switch Ratings (Robert L. Nuckolls, III)
18. 11:07 AM - Re: Switch Ratings (Robert L. Nuckolls, III)
19. 11:10 AM - Re: Switch contact rattings which is best for this app (Brian Lloyd)
20. 11:29 AM - Re: Engine analyzer OFF - Avionics Master (Dave N6030X)
21. 12:50 PM - Re: Engine analyzer OFF for engine start? (Ken)
22. 02:19 PM - Re: Fuel Pump Switch(es) (G McNutt)
23. 03:17 PM - Re: "Oversized" RG batteries and small generators (Robert L. Nuckolls, III)
24. 07:38 PM - Re: Fuel Pump Switch(es) (Hinde, Frank George (Corvallis))
25. 07:40 PM - Re: Fuel Pump Switch(es) (Hinde, Frank George (Corvallis))
26. 09:24 PM - Re: Fuel Pump Switch(es) (Brian Lloyd)
Message 1
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| Subject: | Re: Transponder antenna location |
--> AeroElectric-List message posted by: FLYaDIVE@aol.com
In a message dated 9/9/06 9:37:19 AM Eastern Daylight Time,
gilles.tatry@wanadoo.fr writes:
> Should the bottom of the front fuselage, 2 ft behind the engine, be a
proper
> location?
> Is it a problem to be so close to the engine, isn't it far better at the
> rear?
>
> Thanks,
>
> Gilles
=================
Gilles:
Keep it away from the exhaust gases. Keep it away from the breather tube.
Place it as perpendicular to the to the earth surface as possible and where it
sits in the center of at least 1 Sq. Ft of aluminum surface. And as close to
centerline as possible. ON THE BELLY!
Basic rule:
If the base station you are trying to communicate with is on the ground then
the antenna should be ON THE BELLY.
The exception to the rule is COM#2, there the antenna should be ON THE TOP.
The reason for that is, COM#2 is used to communicate while on the GROUND and
the base station antennas are UP above the plane. You don't want to transmit
into the ground.
Examples (ON THE BELLY):
COM#1
XPONDER
ADF
LOC/GS
RNAV
and VOR, yet 99% of VOR antennas are mounted on the rudder. [Not on my RV-6
... On the Belly at the tail]
Examples (ON THE TOP)
COM#2
GPS [Gee, I wonder why?]
ELT [Gee, I wonder why?]
Hope this helps.
Barry
"Chop'd Liver"
"Show them the first time, correct them the second time, kick them the third
time."
Yamashiada
Message 2
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| Subject: | Re: Alternator Problem - Not in plane |
--> AeroElectric-List message posted by: FLYaDIVE@aol.com
In a message dated 9/9/06 10:54:08 AM Eastern Daylight Time,
ceengland@bellsouth.net writes:
> If they came off small cars, they might not be rated for that much
> current & unable to maintain voltage if you demand excess current.
>
> Another thought: are they internally or externally regulated? If
> external & you're using a regulator built into the test set, are you
> sure the test set regulator is set correctly and are you sure the test
> set voltmeter is accurate? Getting the same volt reading for all using
> one test set & a different, same volt reading for all on another test
> set seems to point at the test sets.
====================================
Charlie:
The rated amperage of the alternator is 90 Amps.
Normal draw is about 15 Amps.
It is internally regulated.
The test benches are at automotive parts stores and rebuilding shops.
At both locations, on all 4 alternators the output was 10.5 V.
This is a crazy problem. It is not a simple problem. I know there is
someone out there with the knowledge and past experience of this situation. If
is
was simple I would have solved it months ago. NO ONE has been able to identify
the problem. Not even Hyundai or Bosch. And it is their alternator's!
Barry
"Chop'd Liver"
Message 3
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| Subject: | Re: Fuel Pump Switch(es) |
--> AeroElectric-List message posted by: FLYaDIVE@aol.com
In a message dated 9/9/06 11:21:44 AM Eastern Daylight Time, kkinney@fuse.net
writes:
> --> AeroElectric-List message posted by: Kevin Kinney <kkinney@fuse.net>
>
> I'm planning a left/right fuel system each with an on/off valve and an aux
> pump on each incoming line.
> I'm thinking of using an on/off/on switch for pumps rather than an on/off
> switch for each pump.
>
> Can anyone offer any thoughts on the downside of this?
>
> Regards,
> Kevin Kinney
========================
WHY!
Kevin:
There are thousands of planes out there with a ONE PUMP boost system running
off on the one common line going to the engine or from the fuel selector.
What I would do though is put a fuel filter on each tank. And then if you want
to go crazy put in a parallel boost pump. That will give you redundancy and of
course more weight and maintenance.
Barry
"Chop'd Liver"
"Show them the first time, correct them the second time, kick them the third
time."
Yamashiada
Message 4
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| Subject: | Re: Switch contact rattings which is best for this |
app
--> AeroElectric-List message posted by: FLYaDIVE@aol.com
In a message dated 9/9/06 3:29:38 PM Eastern Daylight Time, jskiba@icosa.net
writes:
> --> AeroElectric-List message posted by: "Jeffrey W. Skiba"
<jskiba@icosa.net>
>
>
> Okay,
>
> I Have gone and confused myself, I am looking at ordering some switches for
> my OBAM aircraft and can't rember which would be better Higher current
> switch
>
> The catalog states two options:
>
> 1: Silver Rated 3A @ 125V AC
>
>
> 2: Gold Rated 0.4 VA max @ 28V AC/DC max
>
>
> My application will be used in a 12-14 Volt system I want the switch with
> the higher switch capability which is it?
>
> THANKS in advance
>
>
> P.s. my guess is option one the silver contacts but for some reason I don't
> think that is correct....
==================================
OK, here is the break down:
Silver is the better conductor - But - Oxidized much more.
Gold is obviously slightly less in conductivity (but, you will never know
that) than Silver - But - for the practical, does not oxidize.
Without getting ridiculous in explaining a switch ... If you Double the
Voltage you Half the current. So a Switch that is rated at 0.4 Amps @ 28 VDC will
be able to handle 0.8Amps @ 14 VDC.
As for your amperage rating of the switch:
1 - Find out what the circuit draw at MAX will be.
2 - Use a switch that is about 50% over rated than the MAX draw.
3 - If a switch is rated in AC DE-RATE the amperage by 36 to 40%
[This is a rule of thumb. It has NEVER FAILED for me. Some pencil pusher
may have worked out a more accurate number but definitely not a better one.]
Barry
"Chop'd Liver"
"Show them the first time, correct them the second time, kick them the third
time."
Yamashiada
Message 5
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| Subject: | Re: John Deere PM alternator regulator |
--> AeroElectric-List message posted by: Ken <klehman@albedo.net>
David Carter wrote:
> --> AeroElectric-List message posted by: "David Carter"
> <dcarter11@sbcglobal.net>
>
> Ken,
>
> For my info what is your last name? I thought at first you would be
> Ken Powell who I have shared info with about Deere PM alternators, but
> the e-mail address is different.
> In any case, could you will in some of the "scenario":
>
> 1. The battery was dead, and you charged the battery from a non-PM
> alternator after starting the engine.
> . . . So, you have two batteries, 1 was dead, 1 was OK enough to start
> engine.
> . . . You have two alternators (a PM and a "standard" - not a bad idea
> when building experience with an unproven application like a Deere on
> an airplane)
> . . . . . and used the non-PM to attempt to charge the dead battery.
Yes with a Z-14, you just clost the crossfeed contactor to parallel the
batteries.
>
> 2. Was the PM alternator isolated from the good battery so it or its
> Deere voltage regulator lacked some needed "excitation"?
Yes. For experimentation I put a few short charges into the completely
dead battery and kept trying the pm alternator. The pm alternator would
not come alive until the dead battery was pretty much up to 12 volts.
This does not bother me as in normal use a dead battery would mean the
alternator has already failed and I have low voltage warning. Mostly I'm
mentioning it in regards to the recent thread where with other
architectures some guys are wiring their units to be able to come alive
with no battery voltage present.
>
> Looks like we need a "functional test" (experiment) to determine
> characteristics of a Deere PM alternator and VR to see how it performs
> in our application: We should find out "on a bench" that the Deere
> system won't work with a dead battery.
I believe I have confirmed that. What does bother me is that the VR
failed while I was conducting the above scenario. I would like to
prevent that in the future as sooner or later I will miss a switch and
run the battery dead again. At home base I will charge it first but this
aircraft will fly to a number of remote locations. At least the VR
failed on rather than off. It seemed to run fine paralleled with the
crossfeed closed as long as I had the total system loads above the pm's
20 amp output.
>
> Actually, there are two dead battery cases that come to mind:
> 1. Before flight, battery is dead. Don't fly with dead battery - so
> this is a ground maintenance scenario.
Yes
>
> 2. During flight, battery dies and I want to continue flight with my
> PM alternator to some suitable landing spot, either "soon" or "procede
> to final destination" (whatever my risk analysis and good judgement
> and experience and prior planning for this scenario may indicate is
> "safe enough")
> .
This does not concern me at all. Loss of either of my systems is not a
show stopper for me and I don't believe it is a significant risk in any
event.
> . . I plan to have two batteries, so 2. would have to include loss of
> BOTH batteries or some portion of the electrical circuit.
>
> Does you experience in this case you are reporting indicate that the
> PM alternator system might stop putting out voltage and current if
> battery power is lost?
Don't know. I donlt think one shorted cell would not stop it. I have
seen several flooded batteries open circuit in operation though and I
never even noticed til shutdown and subsequent restart attempt. I am not
confident that would happen with this regulator though because I don't
really know why it failed in this case. I am certain that it failed
before it was heavily loaded and before it had a chance to heat up
significantly. I suspect that it won't tolerate this scenario. Note that
my OVM cut off power into the VR but the VR still failed.
Ken Lehman
(haven't put my last name on a list in years other than in my address
but this list is pretty large now I guess)
>
>
> David Carter
>
> ----- Original Message ----- From: "Ken" <klehman@albedo.net>
> To: <aeroelectric-list@matronics.com>
> Sent: Saturday, September 09, 2006 2:31 PM
> Subject: AeroElectric-List: John Deere PM alternator regulator
>
>
>> --> AeroElectric-List message posted by: Ken <klehman@albedo.net>
>>
>> I can now say for certain that the AM101406 regulator will not come
>> to life with a totally dead battery. Since I was at homebase,
>> without power for a charger, and like to experiment, I attempted to
>> charge the dead battery by closing the Z-14 cross feed contactor and
>> charging the dead battery with the good alternator for a few minutes
>> until the PM alternator came to life. I wouldn't recommend that and
>> in this case it seems to have caused the regulator to fail full on. I
>> don't really know why it failed as the rpm was modest (well below the
>> max output capability of the 20 amp PM alternator) and it is not
>> particularly uncommon to have dead batteries on the small tractors
>> that these are original equipment on. Further the regulator is on the
>> cool side of the firewall.
>>
>> My best theory is that the totally dead small AGM battery allowed
>> the output to overvoltage some component in the regulator. I do not
>> have a battery contactor so I felt that there was no need for a large
>> electrolytic capacitor on the output since the battery would never
>> be disconnected. The oem application doesn't have a capacitor. AFAIK
>> totally dead batteries can be reluctant to take a charge at first so
>> maybe it wasn't absorbing enough current initially to dampen the
>> output pulses?? Again I wouldn't have expected that to fail a
>> regulator designed to work with up to 200vac open circuit voltage
>> from the alternator.
>>
>> The OVM worked perfectly. It is wired to interupt the line from the
>> alternator to the regulator. In further experimenting, the little 40
>> amp relay does not seem to have suffered noticeably from a few 20 amp
>> disconnects. I also learned that a single 9ah battery will start the
>> subaru rather nicely so all in all I have obtained some value for the
>> cost of my experimentation ;) I guess I also obtained some value
>> from the OVM modules ;)
>>
>> As a shot in the dark I am thinking of putting a capacitor on the
>> output of the regulator. That would leave the capacitor permanently
>> wired across the battery through the b-lead circuit breaker. I don't
>> think transorbs there would help. Any other suggestions? The obvious
>> one is to charge the battery first but that is not always convenient
>> as sooner or later I will likely run a battery dead again in some out
>> of the way place.
>>
>> I do not have a charging indicator lamp wired to the regulator but I
>> am assuming that is irrelevant.
>>
>> Ken
>>
Message 6
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| Subject: | Glowing Warning Lights |
I have 2 of the B&C LR3C-14 regulators hooked up to warning lights on my
panel. The warning lights are LED. They work fine, flashing when the voltage
is low. I finally got my plane out at night an noticed that both warning
lights have a dim glow. My other warning lights are totally dark.
Any ideas?
Mike Easley
Lancair ES
Colorado Springs
Message 7
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| Subject: | Re: John Deere PM alternator regulator |
--> AeroElectric-List message posted by: Dave N6030X <N6030X@DaveMorris.com>
Many in the Corvair group (www.FlyCorvair.com) are using this same
John Deere generator/VR combo. You might take up the question there
and find out what people have witnessed. The guy who's probably
flown more hours with that combo than anybody is Gus Warren down at
William Wynne's hangar in Florida.
Dave Morris
At 07:38 AM 9/10/2006, you wrote:
>--> AeroElectric-List message posted by: Ken <klehman@albedo.net>
>
>David Carter wrote:
>
>>--> AeroElectric-List message posted by: "David Carter"
>><dcarter11@sbcglobal.net>
>>
>>Ken,
>>
>>For my info what is your last name? I thought at first you would
>>be Ken Powell who I have shared info with about Deere PM
>>alternators, but the e-mail address is different.
>>In any case, could you will in some of the "scenario":
>>
>>1. The battery was dead, and you charged the battery from a non-PM
>>alternator after starting the engine.
>>. . . So, you have two batteries, 1 was dead, 1 was OK enough to
>>start engine.
>>. . . You have two alternators (a PM and a "standard" - not a bad
>>idea when building experience with an unproven application like a
>>Deere on an airplane)
>>. . . . . and used the non-PM to attempt to charge the dead battery.
Message 8
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| Subject: | Fuel Pump Switch(es) |
--> AeroElectric-List message posted by: "glen matejcek" <aerobubba@earthlink.net>
Hi Kevin-
>I'm planning a left/right fuel system each with an on/off valve and an aux
pump
>on each incoming line.
>I'm thinking of using an on/off/on switch for pumps rather than an on/off
switch
>for each pump.
>Can anyone offer any thoughts on the downside of this?
Yup, there are a few. Other folks have touched on most of them already.
The fusing issue could be handled by either putting the FP fuses downstream
of a SPDT center off switch with a larger fuse at the bus (for a total of
3), or by using a DPDT center off switch and two feeds from 2 fuses at the
bus(ses). The former arrangement would have the single feed wire, the
connectors at each end, the big fuse at the bus, and the switch itself as
'single point of failure' nodes. The latter arrangement would reduce the
single point of failure nodes to just the switch itself, rather than all
the other stuff . The most bullet proof system would indeed involve
separate switches for the individual pumps, which would ideally be fed by
separate busses. On balance, having one fuse, one feed wire, and one
switch controlling two pumps leaves you with no less redundancy than my
single pump system, and actually has a smidge more. Unless, of course,
your pumps are inherently less reliable than mine. I have no info on that,
tho-
Having typed this all out, and considering that the electric fuel pumps are
already a back up for the mechanical pump, I'd personally stick with the
single electric pump solution. Especially if one only had one bus to draw
power from. If you are committed to two pumps, I'd probably be perfectly
happy with the single switch, three fuse arrangement. Two electric fuel
pumps gets into the 'belts and suspenders' zone, and complete independent
power systems seems to get into the 'belt, suspenders, and duct tape' zone.
As ever, this is worth precisely what you've paid for it-
glen matejcek
aerobubba@earthlink.net
Message 9
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| Subject: | Engine analyzer OFF for engine start? |
--> AeroElectric-List message posted by: Kelly McMullen <kellym@aviating.com>
I'm installing an EI UBG16. The instructions are very clear that they
believe the unit should be on an avionics switch and turned OFF for
engine start. Which of course raises the question in my mind, why?
Did they shortcut on voltage regulation or spike/noise protection for
the units power supply?
The aircraft in question has a Delco 50 amp generator and a Zeftronics
solid state regulator, which appears to be very good at holding 14.1 v
at all rpms above 1100.
Message 10
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| Subject: | Re: Glowing Warning Lights |
--> AeroElectric-List message posted by: Matt Prather <mprather@spro.net>
Mike,
I seem to remember that the regulator was designed to drive incandescent
lamps instead of LED's. I can't remember why the regulator produces a
bias on the warning circuit.. At any rate, lamps won't produce any
light at low voltage/current bias, but LED's will. I think the fix was
to put a high value resistor (1kohm?) across the leads of the LED. It's
in the archive as I recall.
Regards,
Matt-
MikeEasley@aol.com wrote:
> I have 2 of the B&C LR3C-14 regulators hooked up to warning lights on
> my panel. The warning lights are LED. They work fine, flashing when
> the voltage is low. I finally got my plane out at night an noticed
> that both warning lights have a dim glow. My other warning lights are
> totally dark.
>
> Any ideas?
>
> Mike Easley
> Lancair ES
> Colorado Springs
>
>*
>
>
>*
>
Message 11
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| Subject: | the George debate |
--> AeroElectric-List message posted by: "Fergus Kyle" <VE3LVO@rac.ca>
The banning of someone, even for misdemeanours, is agreed to be a failure of
some sort in the system. But I believe it is also a failure of some
measureable dimension, in that eventually one must decide whether the act
reduces in effectiveness or increases it.
I came to an independent conclusion that the 'failure' is a lesser dimension
than the neglect to ban. It is the net which carries such value after all.
That is why I said "be gone" with regret but with conviction. To Eric may I
say I admire your stance if I cannot agree to its significance in this
instance. It needed to be said. As with Jensen I received a vituperative
personal message that was complete twaddle. I suspect professional help is
wanted here.
In the meantime I am determined to side with Bob N because of his attitude
and his understanding. His was an exemplary presentation at our EAA chapter,
and I will not have him maligned - this is MY net too.
Ferg Kyle
Europa A064 914 Classic
Message 12
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| Subject: | Re: Transponder antenna location |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
At 03:31 PM 9/9/2006 +0200, you wrote:
>--> AeroElectric-List message posted by: "Gilles Tatry"
><gilles.tatry@wanadoo.fr>
>
>Should the bottom of the front fuselage, 2 ft behind the engine, be a
>proper location?
>Is it a problem to be so close to the engine, isn't it far better at the rear?
>
>Thanks,
>
>Gilles
I guess I don't know how to quantify "proper". Everything in
the choice of system architectures is a trade off. As an antenna
guy I could demand of my fellow airplane builders that they provide
me with installation conditions aboard the airplane that approach
the idealized antennas I can build and fully test in the lab. By
the same token, gurus of other disciplines could impose similar
constraints that make their installations look good too. The
end result is a product that performs poorly and looks so bizarre
that nobody would want to be seen flying it.
It's not in the spirit of compromise that we work together to
craft a product that performs adequately -AND- attracts customers.
It a goal of "optimized" performance given a relatively inflexible
platform. Once optimization is achieved, then performance needs to
be evaluated for adequacy to the task.
In the case of antennas, adequacy to the task is dependent
on the user's mission requirements. I've seen relatively
mediocre antennas slammed by pilots who routinely needed
to talk to RCO's on the horizon while others who only talked
to other airplanes and controllers in the airport control area
thought it worked "great".
In the case of transponder antennas, the manufacturer will suggest
coax length limits based on perceived reductions in the optimized
performance of his product (usually the receiver side) to "hear"
that very strong interrogation pulse shot out to the aircraft from
the ground based radar afar.
In the instance were considering, moving the antenna say 5' further
aft might reduce receive sensitivity by some factor we can deduce
by use of a coax loss calculator found at:
http://www.timesmicrowave.com/cgi-bin/calculate.pl
Plug in RG-400, 1050 Mhz and and a RUN of 6'. We find
that a typical installation has an attenuation of about 0.9 db.
Now, plug in 11' for an installation further aft and we get
1.7 db or an ADDITIONAL 0.8 db of attenuation.
If one chooses to worry about this, we could go to
one of the super-sexy coaxes like LMR-400 for a 6 foot
loss of 0.3 db and 11 foot loss of 0.5 db . . . still better
than 6' of RG-400.
Now, suppose we went flying and did some testing of our
transponder's ability to be "read" by ground stations
and could switch back and forth between an idealized
installation per the book: "right under the pilot's
seat antenna and 6' of LMR-400" and the "compromised
location and 11' of RG-400".
We're talking about such small changes in the grand
scheme of things as to make differences detectable in anything
less than a precision antenna lab environment. The guy
on the ground and the guy in the air will have zero
probability of telling which is the "worse" antenna
buy observing behavior of the electro-whizzies in front
of them.
Bob . . .
> --> AeroElectric-List message posted by: "Robert L. Nuckolls, III"
> <nuckollsr@cox.net>
>
> At 10:28 AM 9/7/2006 -0400, you wrote:
>
> >--> AeroElectric-List message posted by: Ken <klehman@albedo.net>
> >
> >Has anyone tried mounting a transponder antenna on the bottom of
> the rear
> >fuselage? That location (about 2/3 of the length of the fuselage back)
> >slopes upward on a Rebel but it is the location least blanked by large
> >gear fairings, and metal radiator ducting. Unfortunately the worst
> signal
> >would likely be forward to where the ground station I'm trying to
> reply to
> >is likely to be during first contact. I am willing to mount the
> >transponder behind me to keep the coax within the 8.8 feet max
> specified
> >by Garmin.
> >
> >The other option seems to be on the roof. That is apparently not
> >recommended and it would be near skylights and my head which I'm not
> >comfortable with. I could get it the minimum recommended 3 feet
> away from
> >the VHF antenna but the high wing might tend to blank ground
> stations to
> >the side. I suspect that roof mounting would provide a better signal to
> >other aircraft which is probably more important to me than a signal to
> >ground so I guess I could put the antenna on the roof back near the
> >tail. It seems silly to invest in a transponder though unless it is
> >likely to perform well with both ATC and also traffic warning
> devices on
> >other aircraft.
>
>
> Any place on the bottom would be preferable to top mounted.
> The aft fuselage location you cited would be fine.
>
> Bob . . .
>
>
> ---------------------------------------------------------
> < What is so wonderful about scientific truth...is that >
> < the authority which determines whether there can be >
> < debate or not does not reside in some fraternity of >
> < scientists; nor is it divine. The authority rests >
> < with experiment. >
> < --Lawrence M. Krauss >
> ---------------------------------------------------------
>
>
Bob . . .
---------------------------------------------------------
< What is so wonderful about scientific truth...is that >
< the authority which determines whether there can be >
< debate or not does not reside in some fraternity of >
< scientists; nor is it divine. The authority rests >
< with experiment. >
< --Lawrence M. Krauss >
---------------------------------------------------------
Message 13
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| Subject: | Re: Glowing Warning Lights |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
At 08:48 AM 9/10/2006 -0600, you wrote:
>--> AeroElectric-List message posted by: Matt Prather <mprather@spro.net>
>
>Mike,
>
>I seem to remember that the regulator was designed to drive incandescent
>lamps instead of LED's. I can't remember why the regulator produces a
>bias on the warning circuit.. At any rate, lamps won't produce any light
>at low voltage/current bias, but LED's will. I think the fix was to put a
>high value resistor (1kohm?) across the leads of the LED. It's in the
>archive as I recall.
>
>
>Regards,
>
>Matt-
Out of my archives:
>I believe I have seen that two 220 ohm resistors can be used in
>conjunction with an LED to act as a OV light on the B&C LR3s. Can
>someone help me with how 220 ohm was determined and why two of them?
>Normally, I use a 600 ohm resistor in series with an LED to operate at
>13.8V. (drop 12V at 20ma). What am I missing here?
To replace an incandescent lamp on the LR-3 Alternator Controller
with and LED, one has to account for a built-in leakage current
for the LR-3's lamp driver picked so that the lamp will illuminate
even when ALL power is removed from the LR-3 as long as the warning
lamp has + power.
This allows the LR-3 to be used with incandescent annunciator
panels that get power from a third source and still annunciate
regulator failure if all power is removed from the regulator.
This leakage is too small to cause an incandescent lamp to glow
but it will cause an LED to glow even when it's supposed to be
dark. Hence, the resistor around the lamp to drive up it's minimum
illumination current to something on the order of 7-8 mA.
So taking the 220 ohm resistors as recommended, let's figure
2v across the illuminated lamp which means we have about 9 mA
used up in the parallel resistor. Figure 12.5v for the bus voltage
while flashing which leaves 10.5 volts across the series resistor
and 47 mA total through it. With 8 mA being sucked off by
the parallel resistor, this leaves 39 mA or so for the LED.
A bit more than its "rated" current but by no means overly
stressful.
The 10.5 volt drop on series resistor at 47 mA suggests
that a 490 milliwatt resistor is called for . . . except
that this is used in a flashing light system with about 50%
duty cycle which cuts dissipation in half. So the 1/2
watt callouts on the drawing at
http://www.aeroelectric.com/Pictures/Schematics/LV_Led.jpg
are plenty conservative.
Why 220 ohm resistors? That was a size stocked by
Radio Shack (stock #271-1111) in packages of
5 for about a dollar. Other resistors could have
worked just as well for the parallel value . . . but
then one would have to buy two 5-paks and throw
away 8 resistors. The design offered gets the job
done with one purchase.
Why the "leakage" in the LR-3? We had a design goal
for the LV warning light to illuminate BOTH for
real Low Volts warning -AND- when the LR-3 had lost
power entirely. To achieve the second goal, the LR-3
had to appear "very leaky" in the OFF state, hence the
resistor optimized for incandescent lamps but something
of a nuisance for LEDs when attempting to directly
substitute the LED for incandescent.
Bob . . .
Message 14
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| Subject: | Re: Engine analyzer OFF for engine start? |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
At 07:12 AM 9/10/2006 -0700, you wrote:
>--> AeroElectric-List message posted by: Kelly McMullen <kellym@aviating.com>
>
>I'm installing an EI UBG16. The instructions are very clear that they
>believe the unit should be on an avionics switch and turned OFF for engine
>start. Which of course raises the question in my mind, why?
>Did they shortcut on voltage regulation or spike/noise protection for the
>units power supply?
>
>The aircraft in question has a Delco 50 amp generator and a Zeftronics
>solid state regulator, which appears to be very good at holding 14.1 v at
>all rpms above 1100.
I'm saddened that any product offered to general aviation
or any other market is still burdened with such admonitions
in their installation instructions. It's a blatant admission
that they're incapable or unwilling to make their product
live in the real-world environment of DC power systems and/or
simply don't understand the world in which they choose to
live. See:
http://www.aeroelectric.com/articles/Whats_all_this_DO160_Stuff_Anyhow.pdf#search=%22avionics%20master%22
http://www.aeroelectric.com/articles/avmaster.pdf
It's the engineering equivalent of child's play to
craft products totally compatible with DC vehicular
power systems.
One can only guess at the rational behind their inclusion
of such a statement . . . and maybe it's for the same reasons
cited by a number of engineers I've queried over the past
30 years:
"Sir, why do the instructions for your product recommend
powering it from an 'avionics' bus 'protected' by an avionics
master switch?" The replies something like, "Gee, I guess
just 'cause other folks are doing it. I personally don't care."
Call them up and ask . . .
Bob . . .
---------------------------------------------------------
< What is so wonderful about scientific truth...is that >
< the authority which determines whether there can be >
< debate or not does not reside in some fraternity of >
< scientists; nor is it divine. The authority rests >
< with experiment. >
< --Lawrence M. Krauss >
---------------------------------------------------------
Message 15
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| Subject: | Re: Fuel Pump Switch(es) |
--> AeroElectric-List message posted by: Brian Lloyd <brian-av@lloyd.com>
On Sun, 2006-09-10 at 04:41, FLYaDIVE@aol.com wrote:
> > I'm planning a left/right fuel system each with an on/off valve and an aux
> > pump on each incoming line.
> > I'm thinking of using an on/off/on switch for pumps rather than an on/off
> > switch for each pump.
> >
> > Can anyone offer any thoughts on the downside of this?
Kevin, I think your approach is just fine. Yes, the switch is a
single-point-of-failure but it shouldn't cause your engine to stop
running as the engine-driven fuel pump should be able to keep the engine
running. To lose the engine you would have to lose the both halves of
the switch, both electric fuel pumps, and the engine driven fuel pump.
> There are thousands of planes out there with a ONE PUMP boost system running
> off on the one common line going to the engine or from the fuel selector.
> What I would do though is put a fuel filter on each tank. And then if you want
> to go crazy put in a parallel boost pump. That will give you redundancy and
of
> course more weight and maintenance.
Barry, I think Kevin's idea of two pumps, each right at the tank, is a
good one. That approach means that your boost pump is never having to
suck against a fuel line thus reducing the chance for vapor lock to
almost zero. (I have experienced a vapor lock in flight on the
engine-driven fuel pump. It gets your attention.) If he is thinking of
running mogas, this might be a very good idea. Most automotive systems
now immerse the fuel pump right in the fuel. This ensures that the pump
has prime and that there is no chance for vapor lock.
Brian Lloyd
Message 16
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| Subject: | Re: Switch Ratings |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
> > --> AeroElectric-List message posted by: "Jeffrey W. Skiba"
><jskiba@icosa.net>
>
> >
> > Okay,
> >
> > I Have gone and confused myself, I am looking at ordering some
> switches for
> > my OBAM aircraft and can't rember which would be better Higher current
> > switch
> >
> > The catalog states two options:
> >
> > 1: Silver Rated 3A @ 125V AC
> >
> >
> > 2: Gold Rated 0.4 VA max @ 28V AC/DC max
> >
> >
> > My application will be used in a 12-14 Volt system I want the switch with
> > the higher switch capability which is it?
> >
> > THANKS in advance
> >
> >
> > P.s. my guess is option one the silver contacts but for some reason I
> don't
> > think that is correct....
>==================================
>OK, here is the break down:
>
>Silver is the better conductor - But - Oxidized much more.
>Gold is obviously slightly less in conductivity (but, you will never know
>that) than Silver - But - for the practical, does not oxidize.
>
>Without getting ridiculous in explaining a switch ... If you Double the
>Voltage you Half the current. So a Switch that is rated at 0.4 Amps @ 28
>VDC will
>be able to handle 0.8Amps @ 14 VDC.
>
>As for your amperage rating of the switch:
>1 - Find out what the circuit draw at MAX will be.
>2 - Use a switch that is about 50% over rated than the MAX draw.
>3 - If a switch is rated in AC DE-RATE the amperage by 36 to 40%
>[This is a rule of thumb. It has NEVER FAILED for me. Some pencil pusher
>may have worked out a more accurate number but definitely not a better one.]
Don't make it any more complicated than it needs to be. Check
out the article at:
http://www.aeroelectric.com/articles/swtchrat.pdf
I've never seen a failure of a switch in a TC or OBAM aircraft
that can be attributed to failure to observe ratings. The ratings
assume many thousands of operations that you're NEVER going to
achieve in your airplane. On the other hand, if you keep your airplane
10 years or longer, it's almost a given that you'll have to replace
some switch, some time . . . but not because you 'overloaded' it. See:
http://www.aeroelectric.com/articles/Anatomy_of_a_Switch_Failure/Anatomy_of_a_Switch_Failure.html
http://www.aeroelectric.com/Pictures/Switches/miniswitches.jpg
Here's and airplane flown often and had over 5 years service on MINATURE
toggles in the landing light, nav light, and strobe circuits. All of
these switches could be said to be 'overloaded' when the catalog
ratings are treated as limits.
Gold contacts are for very small signal switching, what Microswitch
calls "non-arcing" in . . .
http://www.aeroelectric.com/Mfgr_Data/Switches/tl_series.pdf#search=%22switch%20ratings%22
We often purchase 5A relays with silver-cad contacts plated with
a thin layer of gold. If NEVER subjected to higher currents, the
gold plating allows the relay to function well in very small signal
switching . . . but if ever used in a higher current application,
the gold layer is damaged and it officially reverts to a silver-cad
contact relay.
Someone at Beech decided years ago that it would be a good thing
to do 100% receiving inspection of all incoming super whippy mil spec
relays.
They set up a test bench and dutifully subjected every incoming relay
to 5A switching loads and pronounced them 'fit for duty'. Months later
we were having a rash of field failures in some circuits due to the
fact that inspection blew off the gold on relays used in both
"power" and "signal" switching applications. An EXPENSIVE way
to learn difference.
Bob . . .
Message 17
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| Subject: | Re: Switch Ratings |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
> > --> AeroElectric-List message posted by: "Jeffrey W. Skiba"
><jskiba@icosa.net>
>
> >
> > Okay,
> >
> > I Have gone and confused myself, I am looking at ordering some
> switches for
> > my OBAM aircraft and can't rember which would be better Higher current
> > switch
> >
> > The catalog states two options:
> >
> > 1: Silver Rated 3A @ 125V AC
> >
> >
> > 2: Gold Rated 0.4 VA max @ 28V AC/DC max
> >
> >
> > My application will be used in a 12-14 Volt system I want the switch with
> > the higher switch capability which is it?
> >
> > THANKS in advance
> >
> >
> > P.s. my guess is option one the silver contacts but for some reason I
> don't
> > think that is correct....
>==================================
>OK, here is the break down:
>
>Silver is the better conductor - But - Oxidized much more.
>Gold is obviously slightly less in conductivity (but, you will never know
>that) than Silver - But - for the practical, does not oxidize.
>
>Without getting ridiculous in explaining a switch ... If you Double the
>Voltage you Half the current. So a Switch that is rated at 0.4 Amps @ 28
>VDC will
>be able to handle 0.8Amps @ 14 VDC.
>
>As for your amperage rating of the switch:
>1 - Find out what the circuit draw at MAX will be.
>2 - Use a switch that is about 50% over rated than the MAX draw.
>3 - If a switch is rated in AC DE-RATE the amperage by 36 to 40%
>[This is a rule of thumb. It has NEVER FAILED for me. Some pencil pusher
>may have worked out a more accurate number but definitely not a better one.]
Don't make it any more complicated than it needs to be. Check
out the article at:
http://www.aeroelectric.com/articles/swtchrat.pdf
I've never seen a failure of a switch in a TC or OBAM aircraft
that can be attributed to failure to observe ratings. The ratings
assume many thousands of operations that you're NEVER going to
achieve in your airplane. On the other hand, if you keep your airplane
10 years or longer, it's almost a given that you'll have to replace
some switch, some time . . . but not because you 'overloaded' it. See:
http://www.aeroelectric.com/articles/Anatomy_of_a_Switch_Failure/Anatomy_of_a_Switch_Failure.html
http://www.aeroelectric.com/Pictures/Switches/miniswitches.jpg
Here's and airplane flown often and had over 5 years service on MINATURE
toggles in the landing light, nav light, and strobe circuits. All of
these switches could be said to be 'overloaded' when the catalog
ratings are treated as limits.
Gold contacts are for very small signal switching, what Microswitch
calls "non-arcing" in . . .
http://www.aeroelectric.com/Mfgr_Data/Switches/tl_series.pdf#search=%22switch%20ratings%22
We often purchase 5A relays with silver-cad contacts plated with
a thin layer of gold. If NEVER subjected to higher currents, the
gold plating allows the relay to function well in very small signal
switching . . . but if ever used in a higher current application,
the gold layer is damaged and it officially reverts to a silver-cad
contact relay.
Someone at Beech decided years ago that it would be a good thing
to do 100% receiving inspection of all incoming super whippy mil spec
relays.
They set up a test bench and dutifully subjected every incoming relay
to 5A switching loads and pronounced them 'fit for duty'. Months later
we were having a rash of field failures in some circuits due to the
fact that inspection blew off the gold on relays used in both
"power" and "signal" switching applications. An EXPENSIVE way
to learn difference.
Bob . . .
Message 18
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| Subject: | Re: Switch Ratings |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
> > --> AeroElectric-List message posted by: "Jeffrey W. Skiba"
><jskiba@icosa.net>
>
> >
> > Okay,
> >
> > I Have gone and confused myself, I am looking at ordering some
> switches for
> > my OBAM aircraft and can't rember which would be better Higher current
> > switch
> >
> > The catalog states two options:
> >
> > 1: Silver Rated 3A @ 125V AC
> >
> >
> > 2: Gold Rated 0.4 VA max @ 28V AC/DC max
> >
> >
> > My application will be used in a 12-14 Volt system I want the switch with
> > the higher switch capability which is it?
> >
> > THANKS in advance
> >
> >
> > P.s. my guess is option one the silver contacts but for some reason I
> don't
> > think that is correct....
>==================================
>OK, here is the break down:
>
>Silver is the better conductor - But - Oxidized much more.
>Gold is obviously slightly less in conductivity (but, you will never know
>that) than Silver - But - for the practical, does not oxidize.
>
>Without getting ridiculous in explaining a switch ... If you Double the
>Voltage you Half the current. So a Switch that is rated at 0.4 Amps @ 28
>VDC will
>be able to handle 0.8Amps @ 14 VDC.
>
>As for your amperage rating of the switch:
>1 - Find out what the circuit draw at MAX will be.
>2 - Use a switch that is about 50% over rated than the MAX draw.
>3 - If a switch is rated in AC DE-RATE the amperage by 36 to 40%
>[This is a rule of thumb. It has NEVER FAILED for me. Some pencil pusher
>may have worked out a more accurate number but definitely not a better one.]
Don't make it any more complicated than it needs to be. Check
out the article at:
http://www.aeroelectric.com/articles/swtchrat.pdf
I've never seen a failure of a switch in a TC or OBAM aircraft
that can be attributed to failure to observe ratings. The ratings
assume many thousands of operations that you're NEVER going to
achieve in your airplane. On the other hand, if you keep your airplane
10 years or longer, it's almost a given that you'll have to replace
some switch, some time . . . but not because you 'overloaded' it. See:
http://www.aeroelectric.com/articles/Anatomy_of_a_Switch_Failure/Anatomy_of_a_Switch_Failure.html
http://www.aeroelectric.com/Pictures/Switches/miniswitches.jpg
Here's and airplane flown often and had over 5 years service on MINATURE
toggles in the landing light, nav light, and strobe circuits. All of
these switches could be said to be 'overloaded' when the catalog
ratings are treated as limits.
Gold contacts are for very small signal switching, what Microswitch
calls "non-arcing" in . . .
http://www.aeroelectric.com/Mfgr_Data/Switches/tl_series.pdf#search=%22switch%20ratings%22
We often purchase 5A relays with silver-cad contacts plated with
a thin layer of gold. If NEVER subjected to higher currents, the
gold plating allows the relay to function well in very small signal
switching . . . but if ever used in a higher current application,
the gold layer is damaged and it officially reverts to a silver-cad
contact relay.
Someone at Beech decided years ago that it would be a good thing
to do 100% receiving inspection of all incoming super whippy mil spec
relays.
They set up a test bench and dutifully subjected every incoming relay
to 5A switching loads and pronounced them 'fit for duty'. Months later
we were having a rash of field failures in some circuits due to the
fact that inspection blew off the gold on relays used in both
"power" and "signal" switching applications. An EXPENSIVE way
to learn difference.
Bob . . .
Message 19
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| Subject: | Re: Switch contact rattings which is best for this |
app
--> AeroElectric-List message posted by: Brian Lloyd <brian-av@lloyd.com>
On Sun, 2006-09-10 at 04:56, FLYaDIVE@aol.com wrote:
> Silver is the better conductor - But - Oxidized much more.
> Gold is obviously slightly less in conductivity (but, you will never know
> that) than Silver - But - for the practical, does not oxidize.
Switches maintain their low on resistance by both mechanical wiping and
by the very tiny arc that occurs on make and break. If you do not pass
any current through a switch, often the mechanical wiping is
insufficient to ensure a low on-resistance. Gold, unlike silver, has the
characteristic that it maintains its low on-resistance regardless of the
current flowing through it. That is why it is used to switch signals
with no appreciable current (like audio signals).
> Without getting ridiculous in explaining a switch ... If you Double the
> Voltage you Half the current. So a Switch that is rated at 0.4 Amps @ 28 VDC
will
> be able to handle 0.8Amps @ 14 VDC.
This is 100% false and incorrect. A switch rated at 0.4A is rated at
0.4A regardless of the voltage. The voltage ratings have to do with
reliably breaking the circuit. This also depends on whether you are
breaking a circuit carrying AC or DC. The amp rating also depends on
whether you are switching a resistive load or a lamp load. The low
resistance of a lamp filament causes a high inrush current so you need a
switch that is designed to carry more current so it isn't damaged by the
inrush current.
Barry, I strongly recommend you go back and reread the Aeroelectric
Connection. Bob does an excellent job of covering these things in there.
In a forum such as this, you really need to be sure of your answer
before you post one.
Brian Lloyd
Message 20
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| Subject: | Re: Engine analyzer OFF - Avionics Master |
--> AeroElectric-List message posted by: Dave N6030X <N6030X@DaveMorris.com>
Bob, it's bizarre to me that the "Avionics Master Switch" is still
touted as a "feature" rather than as a "single point of failure
liability" in most classified ads I've seen recently for
airplanes. Clearly you/we still have a lot of educating to do! :)
Dave Morris
At 12:50 PM 9/10/2006, you wrote:
>--> AeroElectric-List message posted by: "Robert L. Nuckolls, III"
><nuckollsr@cox.net>
>
> "Sir, why do the instructions for your product recommend
> powering it from an 'avionics' bus 'protected' by an avionics
> master switch?" The replies something like, "Gee, I guess
> just 'cause other folks are doing it. I personally don't care."
Message 21
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| Subject: | Re: Engine analyzer OFF for engine start? |
--> AeroElectric-List message posted by: Ken <klehman@albedo.net>
Hi Kelly
Just an observation but the GRT engine monitor specifically recommends
powering it up before engine start and confirming zero oil pressure
indication. On my particular installation it resets anyway during start
but I have not investigated whether it is voltage dropout during
cranking or momentary loss of power from my marine key switch which
controls power to it and the starter. It is back up in a second or so
anyway.
Ken L.
Kelly McMullen wrote:
> --> AeroElectric-List message posted by: Kelly McMullen
> <kellym@aviating.com>
>
> I'm installing an EI UBG16. The instructions are very clear that they
> believe the unit should be on an avionics switch and turned OFF for
> engine start. Which of course raises the question in my mind, why?
> Did they shortcut on voltage regulation or spike/noise protection for
> the units power supply?
>
> The aircraft in question has a Delco 50 amp generator and a Zeftronics
> solid state regulator, which appears to be very good at holding 14.1 v
> at all rpms above 1100.
Message 22
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| Subject: | Re: Fuel Pump Switch(es) |
--> AeroElectric-List message posted by: G McNutt <gmcnutt@shaw.ca>
Kevin, aside from the on/off switch debate, an on/off valve on each
tank introduces problems and complexity into emergency procedures for a
fuel delivery interruption. For example if you had a blockage or
inadvertently ran a tank dry you will have to reposition two fuel
valves, presumably on opposite sides of the cockpit.
Also check valves may be required to prevent fuel transfer if both tank
valves were inadvertently left open?
George in Langley BC
Kevin Kinney wrote:
> --> AeroElectric-List message posted by: Kevin Kinney <kkinney@fuse.net>
>
> I'm planning a left/right fuel system each with an on/off valve and an aux pump
on each incoming line.
> I'm thinking of using an on/off/on switch for pumps rather than an on/off switch
for each pump.
>
> Can anyone offer any thoughts on the downside of this?
>
> Regards,
> Kevin Kinney
>
>
Message 23
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| Subject: | Re: "Oversized" RG batteries and small generators |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
Received a clarification from Skip Koss at Concorde on the
a topic earlier this week where it was suggested that putting
"too large" and RG battery in an airplane with a small generator
(<35A) was potentially harmful to the generator.
Skip forwarded me a note that he'd sent to AOPA Pilot magazine
that included the following:
-----------------
My reference to small capacity generating systems is not for the protection
of the generator but for the airframe wire and C/B. I have had several reports
from operators of post WWII light airplanes (Ercoupes and Stinsons etc,) of
"After
an engine start, I have to reset the C/B around 5 times before the battery
charge
current is low enough to not pop the breaker"
Typically the RG-35AXC will accept 50 amps at 14 volts for a minute or so after
a start, before the current tapers down to less than 25 amps, so I recommend to
these operators to only use the lower plate count batteries that have a higher
internal resistance, so they won't over tax their wiring etc.
-----------------
So it seems that Skip's recommendations were mis-interpreted. The
circuit breaker tripping phenomenon in these small generator airplanes
is a predecessor to the nuisance-tripping of b-lead breakers in
modern airplanes.
Customer's airplanes were "peddling hard" to recharge the larger,
lower impedance battery which held the generating system at or
slightly above the nameplate rated output. As one customer noted,
he had to reset the breaker several times before it would stay in.
Skip's concerns were (based on tripping of the breaker) mostly
for wiring . . . but we know that as much as 200% overload beyond
the as-installed rating of the wire doesn't place it in imminent
danger.
I wasn't aware that the generator systems would suffer from the
same types of nuisance trips that alternators in most TC aircraft
do. The 60A breaker on a 60A alternator is designed to nuisance
trip. It took some serendipitous installations of modern hardware
in older airplanes to bring the condition forward. It seems the
phenomenon goes back a lot further than the beginning of the
alternator era. It's seldom a problem because most generators
and alternators are normally lightly loaded. A modern, perhaps
larger sized RG battery offers an opportunity to tax the system to
nameplate ratings of the equipment for extended periods of time.
If the system is designed to nuisance-trip, then this scenario
will get breakers pop'n. Interestingly enough, upgrading an older
airplane fitted with a 60A alternator could produce exactly
the same effects; a relatively 'trouble-free' airplane could
suddenly exhibit the symptom by simply changing out a flooded
cell battery for an RG battery.
Bob . . .
---------------------------------------------------------
< What is so wonderful about scientific truth...is that >
< the authority which determines whether there can be >
< debate or not does not reside in some fraternity of >
< scientists; nor is it divine. The authority rests >
< with experiment. >
< --Lawrence M. Krauss >
---------------------------------------------------------
Message 24
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| Subject: | Fuel Pump Switch(es) |
--> AeroElectric-List message posted by: "Hinde, Frank George (Corvallis)" <frank.hinde@hp.com>
I have an electric pump in each wing root and NO mechanical pump...I
assumed this system was the same but if it has a mechanical pump then
sure a single switch would be just fine.
Frank
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Brian
Lloyd
Sent: Sunday, September 10, 2006 10:57 AM
Subject: Re: AeroElectric-List: Fuel Pump Switch(es)
--> AeroElectric-List message posted by: Brian Lloyd
--> <brian-av@lloyd.com>
On Sun, 2006-09-10 at 04:41, FLYaDIVE@aol.com wrote:
> > I'm planning a left/right fuel system each with an on/off valve and
> > an aux pump on each incoming line.
> > I'm thinking of using an on/off/on switch for pumps rather than an
> > on/off switch for each pump.
> >
> > Can anyone offer any thoughts on the downside of this?
Kevin, I think your approach is just fine. Yes, the switch is a
single-point-of-failure but it shouldn't cause your engine to stop
running as the engine-driven fuel pump should be able to keep the engine
running. To lose the engine you would have to lose the both halves of
the switch, both electric fuel pumps, and the engine driven fuel pump.
> There are thousands of planes out there with a ONE PUMP boost system
> running off on the one common line going to the engine or from the
fuel selector.
> What I would do though is put a fuel filter on each tank. And then if
> you want to go crazy put in a parallel boost pump. That will give you
> redundancy and of course more weight and maintenance.
Barry, I think Kevin's idea of two pumps, each right at the tank, is a
good one. That approach means that your boost pump is never having to
suck against a fuel line thus reducing the chance for vapor lock to
almost zero. (I have experienced a vapor lock in flight on the
engine-driven fuel pump. It gets your attention.) If he is thinking of
running mogas, this might be a very good idea. Most automotive systems
now immerse the fuel pump right in the fuel. This ensures that the pump
has prime and that there is no chance for vapor lock.
Brian Lloyd
Message 25
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| Subject: | Fuel Pump Switch(es) |
--> AeroElectric-List message posted by: "Hinde, Frank George (Corvallis)" <frank.hinde@hp.com>
On my electric only system I simply switch pumps to switch tanks...No
selector valve...Just a non return valve in each line joining to a tee
then up to the standards vans selector that has been plumbed to act as
an on-off valve.
The valve has 4 ports so its simple to configure it this way.
System has now flown a total of 2.8 hours...:)
Frank
7a
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of G
McNutt
Sent: Sunday, September 10, 2006 2:21 PM
Subject: Re: AeroElectric-List: Fuel Pump Switch(es)
--> AeroElectric-List message posted by: G McNutt <gmcnutt@shaw.ca>
Kevin, aside from the on/off switch debate, an on/off valve on each
tank introduces problems and complexity into emergency procedures for a
fuel delivery interruption. For example if you had a blockage or
inadvertently ran a tank dry you will have to reposition two fuel
valves, presumably on opposite sides of the cockpit.
Also check valves may be required to prevent fuel transfer if both tank
valves were inadvertently left open?
George in Langley BC
Kevin Kinney wrote:
> --> AeroElectric-List message posted by: Kevin Kinney
Message 26
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| Subject: | Re: Fuel Pump Switch(es) |
--> AeroElectric-List message posted by: Brian Lloyd <brian-av@lloyd.com>
On Sep 10, 2006, at 7:39 PM, Hinde, Frank George (Corvallis) wrote:
> --> AeroElectric-List message posted by: "Hinde, Frank George
> (Corvallis)" <frank.hinde@hp.com>
>
> On my electric only system I simply switch pumps to switch tanks...No
> selector valve...Just a non return valve in each line joining to a tee
> then up to the standards vans selector that has been plumbed to act as
> an on-off valve.
My only concern with that would be that a pump failure could render
1/2 your fuel unavailable. Several aircraft have been lost on long
over-water flights when electric transfer pumps have failed thus
rendering necessary fuel unavailable. Something to think about.
Brian Lloyd 361 Catterline Way
brian HYPHEN av AT lloyd DOT com Folsom, CA 95630
+1.916.367.2131 (voice) +1.270.912.0788 (fax)
I fly because it releases my mind from the tyranny of petty things . . .
Antoine de Saint-Exupry
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