Today's Message Index:
----------------------
1. 05:49 AM - Re: Z-19 and considerations of SYSTEM reliability ()
2. 10:08 AM - Re: Ground loop risk? (Robert L. Nuckolls, III)
3. 10:25 AM - Re: Re: Z-19 and considerations of SYSTEM reliability (Robert L. Nuckolls, III)
4. 11:15 AM - Re: Re: Z-19 and considerations of SYSTEM reliability (Robert L. Nuckolls, III)
5. 12:33 PM - Engine sensor ground (vicster_26)
6. 04:31 PM - Re: Z-19 (Robert L. Nuckolls, III)
7. 04:36 PM - Ver 11.1 of the Data CD is uploaded (Robert L. Nuckolls, III)
Message 1
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Subject: | RE: Z-19 and considerations of SYSTEM reliability |
10/13/2007
Hello Bob, You wrote: " . . . and the pump is already ON for takeoff and
landing."
Just a reminder that in some aircraft the electrically driven fuel boost
pump is not turned on for takeoff or landing.
The problem in those aircraft is that with the engine driven fuel pump and
the electrically driven fuel boost pump both operating the engine can be
drowned in fuel and not operate properly or at all.
The function of the electrically driven fuel boost pump in those aircraft is
to prime the engine prior to starting the engine and to be turned on in
flight in case of failure of the engine driven fuel pump.
'OC' Says: "The best investment we can make is the effort to gather and
understand knowledge."
--------------------------------------
Time: 06:54:48 AM PST US
From: "Robert L. Nuckolls, III" <nuckolls.bob@cox.net>
Subject: AeroElectric-List: RE: Z-19 and considerations of SYSTEM
reliability
..... snip .............
Our low-wing, TC aircraft have been fitted with
boost pumps since day one. 95+ percent of all engine
falters in flight have to do with fuel issues.
We were taught to hit the pump switch first. Perception,
interpretation and reaction took perhaps two seconds.
. . . and the pump is already ON for takeoff and
landing. So, what is the return on investment of
adding an automatic "failover" device in those aircraft?
Now, if these engines tend to quit and be hard to
get restarted then perhaps some form of automatic,
fast reaction system is called for. But if it just
falters, windmills and recovers immediately upon
return of fuel flow, then perhaps the automatic
system is less than elegant. THAT decision is
entirely yours . . . I'm only suggesting that
you ponder the decision with good data and a goal
of arriving at the elegant solution.
Bob . . .
Message 2
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Subject: | Re: Ground loop risk? |
At 05:03 PM 10/12/2007 -0400, you wrote:
>
>I'm feeding my strobes from the 12 volt buss behind the panel.
>Is it necessary to run the ground for the strobes back to the panel ground
>buss, or can I just run the ground to the battery terminal since I'm in
>that vicinity?
>I'm trying to save a wire going forward.
>Will I risk a ground loop if I have more than one ground termination point?
What kind of airplane? If a metal airplane it is
perfectly useful to use local grounds for
landing lights
taxi lights
nav lights
pitot heaters
strobe power supplies
landing gear hydraulic pumps
etc.
These are ALL potential antagonists
for loading alternator noise onto the
airframe. But taking potential victims
to the single point grounds on firewall
and/or instrument panel as suggested
in Figure Z-15 of:
http://aeroelectric.com/articles/Rev11/AppZ_R11K.pdf
Bob . . .
Message 3
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Subject: | Re: RE: Z-19 and considerations of SYSTEM reliability |
At 08:48 AM 10/13/2007 -0400, you wrote:
>
>10/13/2007
>
>Hello Bob, You wrote: " . . . and the pump is already ON for takeoff and
>landing."
>
>Just a reminder that in some aircraft the electrically driven fuel boost
>pump is not turned on for takeoff or landing.
>
>The problem in those aircraft is that with the engine driven fuel pump and
>the electrically driven fuel boost pump both operating the engine can be
>drowned in fuel and not operate properly or at all.
>
>The function of the electrically driven fuel boost pump in those aircraft
>is to prime the engine prior to starting the engine and to be turned on in
>flight in case of failure of the engine driven fuel pump.
Sure . . . which re-enforces the notion that NOTHING
written anywhere by anyone that is not specific to
a study of demonstrated test data about a particular
design is to be taken as gospel. Every new recipe
for success combines simple ideas for the purpose
of meeting a design goal. It's up to the writer
of specific instructions to explain the rationale
for that particular combination of parts and recommend
a modus operandi for that system.
This is what the 40-hour fly-off is all about.
But many builders have put their own flavors onto
another builder's recipe. Too many modified recipes
have been turned loose on open skies and grinning pilots
with undiscovered potential for problems. Its fortunate
that reliance on electrical systems issues is Waaaaayyy
down the list of things that routinely bend airplanes
and kill folks. Fiddling with these recipes generally
don't generate much physical risk, only surprise and
cost of ownership. But we're talking about powerplants
here so the details are worthy of extra attention.
Now, may I take you to task my friend for, "The function
of an electrically driven fuel boost . . .". The POH
for many of the aircraft I fly instructs a pilot to turn
the boost pump on for take-offs and landings.
Bottom line is that there should be GOOD reasons
for doing or not doing a lot of things on our
airplanes . . . but the final word needs to
come from designers and testers that have, "Been
there. Done that." All other assertions are worthy
of measured skepticism and further study.
>'OC' Says: "The best investment we can make is the effort to gather and
>understand knowledge."
HEAR, Hear!
Bob . . .
Message 4
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Subject: | RE: Z-19 and considerations of SYSTEM reliability |
At 10:20 AM 10/12/2007 -0500, you wrote:
>
>Thanks Bob,
>
>I can't seem to find the email but I think Eggenfellner has decided that a
>simple switch on Pump#2 is fine. They were having too much trouble with the
>pressure switch for automatic fail-over.
>
>As a computer geek I find it so hard to resist "automatic techno gadgets"!
>Thanks for the detailed exhortation.
Yup, a lot of what's being done in new systems
design is driven more by what we're capable of
doing as opposed to crafting the minimum parts
count, highest reliability, lowest cost (i.e.
elegant) solution.
The drive to add whippy new features is oft offered
by folks who have little or poor connection to
end users. We see this in the Heavy Iron Aviation
all the time. In addition to bureaucratic
pressures to do or not do things, decisions
about what's attractive to the end user (owners
and pilots) tend not to be made with the elegant
solution as a design goal.
Walter, Dwayne, Ed, Arthur, Bill, Al and Lloyd
would be sad to observe the remnants of their
legacies.
Bob . . .
Message 5
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Subject: | Engine sensor ground |
Hello,
I understand that in a single point ground system, those sensors that are connected
to the engine case should have their ground returned from the instrument
to the engine side of the firewall ground. A question here, with some of these
new electronic engine analyzers where you have multiple sensors connecting to
one instrument via a D-sub connector, how do you resolve the issue of returning
the relevant ground back to engine side when the ground is grounded internally
in the instrument. In my case, most of the sensors are isolated from the
engine except for the Oil Temp which is obviously threaded directly to the engine
case.
I have a factory built airplane with very basic instrumentation and avionics, in
fact it had just one old chunky radio and the avionics master switch is simply
a 5amp switch type circuit breaker. Now that I am installing a few more avionics,
is there any problems with connecting all of them to this one circuit breaker
or perhaps running a bus from this switch/circuit breaker to separate circuit
breakers for each avionics?
Thanks in advance
Vic
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=139789#139789
Message 6
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At 08:46 PM 10/11/2007 -0400, you wrote:
>Bob,
>
>I have decided on a ULPower 260i engine for my Europa. It has one ECU and
>one fuel pump. In my book there is a Z-19 drawing, but I can't find it on
>the disk I picked up at your seminar or on your latest download from your
>site. Do you suppose that you could email it to me? Thanks
>
>Vaughn Teegarden
><mailto:vaughnray@bvunet.net>vaughnray@bvunet.net
All of the latest drawings are on the website's
Page-Per-System library at:
http://www.aeroelectric.com/PPS/ACAD_Architecture_Dwgs/
for the AutoCAD .dwg format and . . .
http://www.aeroelectric.com/PPS/Adobe_Architecture_Pdfs/
for the .pdf versions.
Your heads-up on the CD download is appreciated.
I forgot to update it. I've loaded Ver 11.1 up at:
http://www.aeroelectric.com/CD
Bob . . .
Message 7
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Subject: | Ver 11.1 of the Data CD is uploaded |
I've just uploaded the latest copy of the 'Connection's
data CD. Version 11.1 zip file may be accessed at:
http://www.aeroelectric.com/CD/AEC_11p1.zip
This is about a 400M file. It can take awhile on even
some "high speed" systems.
Bob . . .
----------------------------------------
( "Problems are the price of progress. )
( Don't bring me anything but trouble. )
( Good news weakens me." )
( -Charles F. Kettering- )
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