Today's Message Index:
----------------------
1. 05:14 AM - Re: Z-13 and Dead Battery (CORRECTION) (Robert L. Nuckolls, III)
2. 05:21 AM - Re: Redundant Fuel pump wiring, 914 Rotax (Robert L. Nuckolls, III)
3. 06:48 AM - Re: Redundant Fuel pump wiring, 914 Rotax (Yahoo hasbroucka)
4. 07:29 AM - Re: Redundant Fuel pump wiring, 914 Rotax (Steve Stearns)
5. 06:14 PM - Re: Redundant Fuel pump wiring, 914 Rotax (Robert L. Nuckolls, III)
6. 06:36 PM - Re: Redundant Fuel pump wiring, 914 Rotax (rayj)
Message 1
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| Subject: | Re: Z-13 and Dead Battery (CORRECTION) |
> But ANY time the battery suffers a total discharge it should
> be recharged and cap checked on the ground to make sure it
> meets your design goals for minimum battery performance. In
> any case, with a battery taking heavy recharge currents from
> the engine driven power sources, I would not turn on much
> in the way of electro-whizzies until the low volts warning
> light has been out for 5-10 minutes. If the ship's voltmeter
> says anything over 11 volts, electro-whizzies should work as
> advertised, but leaving the ground WITHOUT assurances that
> the battery is taking on a charge is NOT good pilotage. <========
Bob . . .
Message 2
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| Subject: | Redundant Fuel pump wiring, 914 Rotax |
>>
>>I believe that I now have an engine that will gladly continue to
>>run, but will not have fuel feed?
>
> What's your proposed battery configuration?
Some years ago we attended to the notion that
redundant systems for an electrically dependent
engine would benefit from some unique battery
configurations and management. At that time, we
were talking about electronic ignition systems.
I wrote an article for Sport Aviation on the
idea for installing a separate, perhaps smaller
battery that would be set aside for the sole
purpose of supporting the engine in case of
alternator failure. I even crafted a LW warning/
Ignition Battery Management Module that would
automate the isolation of a second battery in
the event of alternator failure.
I sold perhaps 100 of those modules over the
years . . . I think Eric has a similar product
too. The same notion could apply to fuel
pumps in your case. Split battery duties between
two separate batteries with one dedicated to
running a pump. The second pump would run from
the main system.
What size battery are you considering now? Have
you crafted a load analysis for your proposed
system? What are your design goals for battery
only ops endurance?
Bob . . .
Message 3
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| Subject: | Redundant Fuel pump wiring, 914 Rotax |
Bob,
Thanks for the thoughtful info.
Last night I spent hours thinking about this, re-reading your book and
writing out several pages of notes and drawings. In the end I was
overlooking that my proposed wiring for the main fuel pump only might,
continue in an OV situation, but under other types of alternator
failure,
where the pilot had to turn off the Alt switch, it would also turn off
the
main fuel pump! Not quite as good a plan as I first thought. This could
be
worked around by adding another relay, but that unreasonably complicates
the
wiring and charging control, negating its usefulness.
The battery being way more reliable than the Alternator, I now agree
that I
am best served to tie both pumps off the battery from separate buses,
main
pump on a pull-able breaker to avoid accidental interruption. I
understand
that the only improvement options are to add a second battery or
Alternator,
which I am not considering for this airplane.
Battery planned to be 16ah RG. Working on load analysis, may be another
week
or so. Fuel endurance is 5.5hr max, though I am not attached to having
that
much Battery only Ops. This is a local fun flier/puddle jumper, so even
two
hours would be a comfortable margin.
Alan , HasbrouckA@yahoo.com
SeaRey Amphibian, framework and hull assembled (not covered). Working on
VFR
avionics and wiring (Dynon Skyview full suite). Top Priority is keep it
light, and place weight forward!
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of
Robert L.
Nuckolls, III
Sent: Monday, January 21, 2013 8:21 AM
Subject: RE: AeroElectric-List: Redundant Fuel pump wiring, 914 Rotax
I believe that I now have an engine that will gladly continue to run,
but
will not have fuel feed?
What's your proposed battery configuration?
Some years ago we attended to the notion that
redundant systems for an electrically dependent
engine would benefit from some unique battery
configurations and management. At that time, we
were talking about electronic ignition systems.
I wrote an article for Sport Aviation on the
idea for installing a separate, perhaps smaller
battery that would be set aside for the sole
purpose of supporting the engine in case of
alternator failure. I even crafted a LW warning/
Ignition Battery Management Module that would
automate the isolation of a second battery in
the event of alternator failure.
I sold perhaps 100 of those modules over the
years . . . I think Eric has a similar product
too. The same notion could apply to fuel
pumps in your case. Split battery duties between
two separate batteries with one dedicated to
running a pump. The second pump would run from
the main system.
What size battery are you considering now? Have
you crafted a load analysis for your proposed
system? What are your design goals for battery
only ops endurance?
Bob . . .
Message 4
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| Subject: | Redundant Fuel pump wiring, 914 Rotax |
Original poster (and Bob's reply) said:
> What happens if there is a failure at (or very near) the battery
> (hot or ground) making an open circuit.
> Those kinds of failures are generally pretty much
> in the 'never happens' category. In other words,
> those wires, terminals, components and craftsmanship
> for installation is so robust by design that they're
> treated much like wing struts and prop bolts . . . not
> part of a failure mode effects analysis.
>
A slightly different emphasis of which I don't think Bob will disagree:
There are a number of areas, of which this is one, in which it is both
reasonable and appropriate to make true the statement that, "Those kinds
of failures are generally pretty much in the 'never happens' category."
Specifically these apply to large feeders, battery connections etc. It
also applies to all of the other non-redundant system (e.g. your flight
controls). But the 'never happens' characteristic only apply if the
appropriate care has been taken.
My strident response to this topic is partially motivated by my finding,
on my then recently acquired "flying" (with ~1000 hrs) LongEz a totally
unacceptable crimp on the main positive terminal feeder coming from the
battery. It was either #2 or #4 wire (it was ~5 years ago) and the
terminal had been applied by one of those smack-it-with-a-hammer
crimpers. It was not gas tight and (presumably after 1000 hrs of
vibration) was quite loose. From my perspective if wasn't ready to
fail, it had already failed...
So I would say: IF you do your homework, and IF you do an appropriatly
"good" job (which is not difficult or tricky) THEN "Those kinds of
failures are generally pretty much in the 'never happens' category."
Steve Stearns
Boulder/Longmont, Colorado
Restoring (since 1/07) and flying again (8/11!): N45FC O235 Longeze
Cothern/Friling CF1 (~1000 Hrs)
Flying (since 9/86): N43732 A65 Taylorcraft BC12D
Message 5
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| Subject: | Redundant Fuel pump wiring, 914 Rotax |
>
>My strident response to this topic is partially motivated by my
>finding, on my then recently acquired "flying" (with ~1000 hrs)
>LongEz a totally unacceptable crimp on the main positive terminal
>feeder coming from the battery. It was either #2 or #4 wire (it was
>~5 years ago) and the terminal had been applied by one of those
>smack-it-with-a-hammer crimpers. It was not gas tight and
>(presumably after 1000 hrs of vibration) was quite loose. From my
>perspective if wasn't ready to fail, it had already failed...
>
>So I would say: IF you do your homework, and IF you do an
>appropriatly "good" job (which is not difficult or tricky) THEN
>"Those kinds of failures are generally pretty much in the 'never
>happens' category."
Well stated. Lack of understanding the physics behind processes
and inattention to details will undo the most reliable and elegant
of constructs.
Some of the most vexing (and expensive) dragons I've slain
ultimately had foundation in lack of understanding
and/or inattention on the part of one or more folks down
the chain of experience.
Even the wizened practitioners will step on their beards . . .
experience alone is not a 100.00% thing. This is why
the very best work for both original design and debugging
poor design and craftsmanship is a team effort. Different
perspectives, diverse curiosities, alternative analysis
is always good even if a particular exploration drives
up a blind canyon. Eliminating wrong answers is just as
valuable as finding the right one . . . when it adds to the
experience base (lessons learned) for the whole.
Yeah, I know the guys who budget man-hours and write the
checks don't always agree . . . some even believe that the
golden suite policies and procedures will ultimately prove
most valuable. However, I've yet to see it demonstrated.
Just because some words are enshrined on a piece of paper
does not guarantee that the ideas behind those words are
sure to prevail.
Bob . . .
Message 6
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| Subject: | Re: Redundant Fuel pump wiring, 914 Rotax |
Bob,
I'm not familiar with the term "golden suite" in this context. A quick
dfn please.
Thanks,
do not archive
Raymond Julian
Kettle River, MN.
"And you know that I could have me a million more friends,
and all I'd have to lose is my point of view." - John Prine
> Yeah, I know the guys who budget man-hours and write the
> checks don't always agree . . . some even believe that the
> golden suite policies and procedures will ultimately prove
> most valuable. However, I've yet to see it demonstrated.
> Just because some words are enshrined on a piece of paper
> does not guarantee that the ideas behind those words are
> sure to prevail.
>
>
> Bob . . .
>
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