Today's Message Index:
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1. 04:29 AM - Re: Re: Z-17 battery/ alternator switch (Stuart Hutchison)
2. 05:42 AM - Re: Re: Starter Hesitation (edward Clegg)
3. 05:57 AM - Re: Hobbs wiring (user9253)
4. 08:51 AM - Re: Hobbs wiring (Paul Millner)
Message 1
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| Subject: | Re: Z-17 battery/ alternator switch |
Thanks Joe & Bob.
I=99ve bought lots of parts from B&C, but in this case my
PlanePower 70A (internally regulated) also seems very well made, with
cooling air intake through the windings, hot air extracted by fans at
both front and back ends, plus a ram-air cooling duct directly targeting
the potted regulator.
The mounting brackets are very solid too, so hopefully the drive belt is
the only part I=99ll ever have to replace.
V/R, Stu
> On 9 Mar 2017, at 04:12, Robert L. Nuckolls, III
<nuckolls.bob@aeroelectric.com> wrote:
>
>> The author explained that aeroplane alternators seem have a higher
rate of failure compared to motor vehicle alternators that are also more
commonly subjected to mud, water and dust ingress. His reasoning was
that in a car the alternator field is isolated during the start sequence
(as are the lights and most other power hungry devices that add to the
battery load) until the key is released to its normal position. By
contrast, when cranking an aeroplane engine with the alternator field
excited, the voltage regulator senses a substantial sag in bus voltage
and attempts to draw max output from the alternator to fix the problem
before the alternator has sufficient RPM to provide the required output.
I reasoned that this was why some manufacturers have split or separate
alternator switches. Any truth to this concept then?
>
> "higher rates of failure" is not very descriptive
> of cause and effect. While it's true that some
> alternators in aircraft have been problematic,
> most of my encounters have been grounded in
> design or manufacturing defect. We used to break
> a lot of brackets on some installations. Piper's
> love affair with the Chrysler 'pancake' alternators
> led to short service life on attach brackets. An
> alternator I conducted failure analysis on a
> few months back had press fit diodes pushed into
> oversized holes at odd angles using a hand-tool
> as opposed to the recommended hydraulic press.
>
>
> <8e94c69.jpg>
>
> The diodes were deprived of good heat sinking and in
> some cases, good electrical conductivity.
>
> The last task I mounted in TC aviation concerned alternators
> that wouldn't stay on line . . . a problem I'd worked at
> least two previous times over 30 years. Focus
> of the investigation was on alternators that had
> demonstrated problems over the years, but in this case
> it was the regulator's o.v. sense system that was
> overly sensitive to normal brush noise from this
> alternator . . . they struggled for weeks to "filter"
> the field leads (with limited success) while in fact,
> it was the regulator that needed to be changed out.
>
> At the same time, alternators supplied by B&C (and
> no doubt others) have an exceedingly low return
> rate.
>
> The hypothesis offered in the article is without
> foundation in physics or practice. If the author
> went to the lab, he would not be able to reproduce
> a failure by duplication of conditions cited in the
> hypothesis.
>
> It's all physics. For every failure there IS a
> combination of conditions leading up to that failure.
> Proper operations of switches by crew are exceedingly
> unlikely to be in the chorus of conditions. Joe is
> correct, a few seconds of full-field operation is
> of no particular hardship on an alternator.
>
>
> Bob . . .
>
Message 2
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| Subject: | Re: Starter Hesitation |
Mine has been doing it for the past 750 hours. I changed out the s relay
with a Sky Tech and it has not done it as much. It only happens when the
engine is hot
Ed
On Wed, Mar 8, 2017 at 10:43 PM RV7ASask <rv7alamb@sasktel.net> wrote:
>
> "Let me ask this. Does this happen only when the engine is hot?
> If so I'll relate my 2 cents"
>
> No, the last start, a couple of days ago, was the first for a couple of
> months and there was a long "pause". Last year this pause was happening
> with both a hot and a cold engine,
>
> David
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=467086#467086
>
>
Message 3
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| Subject: | Re: Hobbs wiring |
You are on the right track if my interpretation of your post is correct. But I
can not say for sure until seeing a complete schematic of your proposed circuit
including the master switch and battery contactor. A picture is worth a thousand
words.
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=467106#467106
Message 4
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| Subject: | Re: Hobbs wiring |
Ron, starter switch is not wired to Hobbs meter.
Paul
Sent from my iPhone
> On Mar 8, 2017, at 7:49 PM, Ron Burnett <ronburnett@charter.net> wrote:
>
> Although I have this engine time on my GRT EIS I would like to have this already
installed additional system on my RV-6A which has a zero time rebuilt Lycoming.
>
> I have a master key and start button which I believe should be spliced into the
starter switch from the lamp, which being red when engine isn't running will
also serve as a reminder to shut it off after the flight.
>
> Then I should wire from the Hobbs meter to my fuse panel. Could someone please
confirm for my pace of mind?
>
> Thanks,
>
> RonBurnett
>
> <D7891D3F-0CEE-4F2F-8694-E4BFA25E7C3F.JPG>
>
>
>
> May you have the Lord's blessings today!
> Sent from my iPad
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