Today's Message Index:
----------------------
1. 05:11 AM - Re: Producing pdf or xps files with ExpressSCH (Scott Klemptner)
2. 06:49 AM - Bendix Magneto Wiring (MikeDunlop)
3. 07:05 AM - Re: Bendix Magneto Wiring (George, Neal Capt 505 TRS/DOJ)
4. 08:01 AM - Re: Re: Producing pdf or xps files with ExpressSCH (Vern Little)
5. 09:14 AM - Re: Re: Garmin believes in Old Wive's Tales. (Robert L. Nuckolls, III)
6. 10:23 AM - Latching Relay Redux (Jeff Luckey)
7. 10:45 AM - Re: What's wrong with this circuit? (Robert L. Nuckolls, III)
8. 11:02 AM - Re: Latching Relay Redux (Robert L. Nuckolls, III)
9. 01:02 PM - Re: Latching Relay Redux (Jeff Luckey)
10. 01:48 PM - Re: Latching Relay Redux (Robert L. Nuckolls, III)
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Subject: | Re: Producing pdf or xps files with ExpressSCH |
=0A=0AVern,=0A=0Ai have been using ExpressSCH for years and it has always b
ehaved this way on both XP and Vista.=0A=0Ai have never found a workaround.
=0A=0A-=0AScott A Klemptner=0Abmwr606 on Yahoo IM=0A
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Subject: | Bendix Magneto Wiring |
Having searched the forum I have found the following:
-------
Is there is any significant degradation in starting
performance when only one mag is hot?
You betcha . . . most engines come with only one impulse coupled mag.
Unless both mags are impulse coupled, you need to add a jumper between
the right mag's p-lead terminal and a nearby switched ground terminal
on the key-type magneto switch. This has the effect of grounding out
the right mag while cranking. It also has the effect of letting the
right mag become "hot" with the engine still moving after an aborted
cranking attempt - been known to break starter castings.
-------------------------
Question is:
My Long-EZ is being fitted with a O-320 B3B that has two impulse couplings! Does
this mean that the jumper between the right mag's p-lead terminal and a nearby
switched ground terminal on the key-type magneto switch (with Start position
- Gerdes A510-2) IS NOT REQUIRED?
This is all described in article at http://www.aeroelectric.com/articles/MagnetoSwitchOptions.pdf
I would like to clarify this now because looking at the engine logs, it shows that
the previous owner had replaced the woodruff key in the starter motor 3 times
within 130 hours! This sounds as if there is a problem with kicking back
on startup.
BTW the engine has now been zero timed and the mags will now be overhauled.
MikeD (U.K.)
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=376706#376706
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Subject: | Bendix Magneto Wiring |
Mike -
If both mags are fitted with impulse couplings, and both function correctly,
you may remove the jumper.
neal
-----Original Message-----
Question is:
My Long-EZ is being fitted with a O-320 B3B that has two impulse couplings!
Does this mean that the jumper between the right mag's p-lead terminal and a
nearby switched ground terminal on the key-type magneto switch (with Start
position - Gerdes A510-2) IS NOT REQUIRED?
This is all described in article at
http://www.aeroelectric.com/articles/MagnetoSwitchOptions.pdf
I would like to clarify this now because looking at the engine logs, it
shows that the previous owner had replaced the woodruff key in the starter
motor 3 times within 130 hours! This sounds as if there is a problem with
kicking back on startup.
BTW the engine has now been zero timed and the mags will now be overhauled.
MikeD (U.K.)
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Subject: | Re: Producing pdf or xps files with ExpressSCH |
Thanks for the confirmation, Scott. =98Express=99 has been
consistently denying that they have a problem. As soon as I said that I
threatened to post it on internet forums, they said that they would have
an engineer look at it. Sounds like they follow the Microsoft support
model (not a compliment).
If you are up to it, an email to =98Express=99 describing
your problem would go a long way... they said that they had never had
anyone report this problem before, therefore I must be wrong (what an
attitude!). My response to them was... =9CI=99m not wrong,
just the first=9D.
Thanks for your support.
Vern
From: Scott Klemptner
Sent: Wednesday, June 27, 2012 5:09 AM
Subject: AeroElectric-List: Re: Producing pdf or xps files with
ExpressSCH
Vern,
i have been using ExpressSCH for years and it has always behaved this
way on both XP and Vista.
i have never found a workaround.
Scott A Klemptner
bmwr606 on Yahoo IM
No virus found in this message.
Checked by AVG - www.avg.com
06/26/12
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Subject: | Re: Garmin believes in Old Wive's Tales. |
At 12:01 AM 6/27/2012, you wrote:
I just find this whole "don't dare turn it on before the engine is
started" argument a little crazy.
Those who have flown the B767 and similar vintage big metal things
will be familiar with the significant CLUNK as engine generators come
online and transfer power, causing various lights and screens to
blank, flicker and carry on spectacularly. Or other effects when the
APU generator comes online and takes over from battery power.
Similarly, there are dozens of potentially 'sensitive'
electro-whizzies firmly attached to the various busses
on most aircraft with DC power system. My first such
product was a pitch trim speed controller and runaway
monitor for the most of the fleet of Lears. It was
stuffed full of C-mos devices. Had we asked for procedures
and systems to 'shut it off during cranking' . . . the
product would never have made it to the production
line.
Yet the 20+ year old comm radios and nav systems made by Collins,
Honeywell, Garmin, etc still survive these power transients, spikes,
and surges. Excactly the same goes for other large aircraft I've
flown. Radios and nav gear were regularly switched on, as a matter of
necessity, before engine start. In almost 30 years of flying these
things, I've never experience an avionics failure due to power
transients when engine-driven power sources have come online and
assumed the load!
Exactly . . . and indeed radios much older. Don't know
about the heavier iron but I was working at Cessna's
single-engine facility when the Avionics Master Switch
was birthed. We were indeed 'killing' a goodly number
of brand new 300 series radios that sported the latest
'transistorized' audio systems and power supplies. It
seemed that radios which worked when the airplane was
parked in the finished goods patch didn't work the next
time the airplane was started.
It was 'assumed' that spikes from the starter were
killing transistors. The AMS seemed like a quick and
easy solution to isolating all radios from those
presumed risks.
In retrospect, I've deduced that it wasn't spikes
that killed radios but 'brown out' transients experienced
during cranking of a new, tight engine on a battery that
might never have been fully topped off and had been setting
on the ramp for 30-60 days.
Those new, relatively fragile, germanium PNP power
transistors were coming out of saturation and going
into second breakdown under low voltage conditions.
It was some years later that the DO-160 tests for
brown out conditions were expanded . . . combined with
more robust silicon transistors and designs by engineers
who were good students of lessons-learned and were
doing a better job.
This morbid fear, bordering on complete paranoia, of avionics being
on before engine start in the small-plane world is quite new to me!
Agreed. But we planted the weeds back about 1965 and
every flight instructor since has watered and fertilized
those weeds dutifully for the 50 years hence. What was
once a misinterpretation of cause and effect out of ignorance
morphed into a full blown superstition. I too was once a
believer but a few years after that experience at Cessna
as a tech writer, I had a responsibility to understand
and apply DO-160 requirements to my work product. The
task turned out to be a real superstition-killer.
Bob . . .
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Subject: | Latching Relay Redux |
Back in 2011 there was some discussion of new latching-type relay/contactors
that might be suitable for use as master relays.
I remember at the time looking at the spec sheets & pricing of some of those
devices and they seemed available & reasonably priced.
I google search earlier this week failed to turn-up any devices that were
reasonably priced and they seemed to have huge lead times.
I want to consider using such a device but if they are difficult to get, I
won't bother. Does anyone have a source(s) for such a device?
TIA
Jeff Luckey
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Subject: | What's wrong with this circuit? |
At 10:30 PM 6/26/2012, you wrote:
I dont think Im totally convinced of the
benefit of multiple busses, main & essential. In
my airplane almost everything is essential
(except perhaps lighting & a few
accessories). My list of essential stuff:
Electronic Ignition, fuel pump, regulator, EFIS,
at least one nav/com, transponder. Everything
else is either not used frequently (like pitot
heat) or has very minimal draw where a minute or
two delay in turning-off the item is not significant.
Actually, it's not a 'essential bus' but an 'endurance bus'.
It's a means by which one can reduce loads on a battery to
the useful necessities for continued flight in the en route
mode. The idea is to design an electrical system with
endurance equal or greater than fuel aboard. This concept
goes to Plan-B for dealing with failure of the least reliable
energy source on the airplane . . . the alternator.
Suggest you review the chapter on system reliability and
List discussions on the philosophy and utility of the
E-bus . . .
Your 'concerns' are significant but may I suggest that
many are of such low risk as to be outside the sphere
of thought for designing your system? The hapless Mr.
Lloyd may have installed every back-up-to-backup system
in his airplane but all went for naught when wires pulled
out of terminal.
A search of FAA Service Difficulty Reports and NTSB accident
reports will show that very few accidents were precipitated
or exacerbated by electrical system failures. Those accidents
that DID have an electrical system component would have been
greatly mitigated by a combination of thoughtful architecture,
good preventative maintenance (don't run batteries 'til they
die) and pilot understanding of how the system worked.
The prime directives for this List are "thougtful architecture
that goes to comfortable tolerance of high risk failures",
"understanding based on simple ideas in physics, processes and
materials" and the study of "lessons learned from the experiences
of others".
With the single main bus that is essentially
wired like a UPS (uninterruptible power supply)
it seems simpler from an operational standpoint.
Simpler for the mitigation what failure for which there
is a demonstrably significant risk?
Not to confuse automatic w/ unknown In this
scenario, the system would produce a Low Batt B
Volts alarm. (and a quick look at the Batt B
voltmeter would indicate not only low but zero).
But what is the risk for "zero volts" on a bus and
what elements make up the constellation of events that
might produce that event. Is it not better to first
reduce those risks by changes in design, process or
materials? After the ingredients that go into your proposed
recipe for success are carefully combed, only then do
you exercise tools necessary to craft a Plan-B for the
failure that might put the mission (or hygene in your
shorts) at risk.
The goal is to comfortably assert that "my airplane
is exceedingly unlikely to suffer an electrical
emergency. It may suffer many failures of components
for which I will suffer the expense of maintenance . . .
but any and all will be no-sweat events."
Un-authorized arc welding (while airborne), very scary!
Scary to contemplate but in reality, so 'gentle' that
it took many flight hours for the effects to achieve
the interesting conclusion. The fact that there was
a Plan-B in the pilots hip pocket paired to other
features of the airplane's architecture turned a
'scary' contemplation into a 'no sweat' event.
Bob . . .
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Subject: | Re: Latching Relay Redux |
At 12:21 PM 6/27/2012, you wrote:
Back in 2011 there was some discussion of new latching-type
relay/contactors that might be suitable for use as master relays.
I remember at the time looking at the spec sheets & pricing of some
of those devices and they seemed available & reasonably priced.
I google search earlier this week failed to turn-up any devices that
were reasonably priced and they seemed to have huge lead times.
I want to consider using such a device but if they are difficult to
get, I won't bother. Does anyone have a source(s) for such a device?
If your design incorporates this, or any other
uniquely crafted product, you're presented with
both 'spares' and 'unconventional operations'
issues. If the design goal is to reduced energy
consumption in the battery contactor, you could
craft a duty-cycle controller that drops the
contactor excitation to about 1/2 say 1 second
after you energize it. More than enough to keep
it closed yet drops heating (energy consuption)
by 75% or so.
Then you can use ANY contactor in the constellation
of similar devices while. What's more, with a
alternate feed path to an E-bus, risks to mission
for failure of your energy conservation device are
covered by the same Plan-B that covers main
alternator failure. The airplane's controls are
consistent with legacy philosophies and no new
spares issues are created.
Bob . . .
Message 9
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Subject: | Latching Relay Redux |
Bob,
All good points, many of which have been discussed on this forum.
I'm currently doing a more academic analysis (you know, when you are stuck
in traffic) as to how such devices might improve a system design (if at all)
but, if they are difficult to obtain then I think the point is moot.
BTW - a "pull & hold" circuit seems to me to be a non-starter - putting a
bunch of 'exotic' circuitry in the critical path of the coil circuit to
accomplish such a trivial task seems to me to be counter-productive. If you
are counting milliamps then your system probably has bigger problems.
-Jeff
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L.
Nuckolls, III
Sent: Wednesday, June 27, 2012 11:02
Subject: Re: AeroElectric-List: Latching Relay Redux
<nuckolls.bob@aeroelectric.com>
At 12:21 PM 6/27/2012, you wrote:
Back in 2011 there was some discussion of new latching-type
relay/contactors that might be suitable for use as master relays.
I remember at the time looking at the spec sheets & pricing of some
of those devices and they seemed available & reasonably priced.
I google search earlier this week failed to turn-up any devices that
were reasonably priced and they seemed to have huge lead times.
I want to consider using such a device but if they are difficult to
get, I won't bother. Does anyone have a source(s) for such a device?
If your design incorporates this, or any other
uniquely crafted product, you're presented with
both 'spares' and 'unconventional operations'
issues. If the design goal is to reduced energy
consumption in the battery contactor, you could
craft a duty-cycle controller that drops the
contactor excitation to about 1/2 say 1 second
after you energize it. More than enough to keep
it closed yet drops heating (energy consuption)
by 75% or so.
Then you can use ANY contactor in the constellation
of similar devices while. What's more, with a
alternate feed path to an E-bus, risks to mission
for failure of your energy conservation device are
covered by the same Plan-B that covers main
alternator failure. The airplane's controls are
consistent with legacy philosophies and no new
spares issues are created.
Bob . . .
-----
No virus found in this message.
Checked by AVG - www.avg.com
Message 10
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Subject: | Latching Relay Redux |
>BTW - a "pull & hold" circuit seems to me to be a non-starter - putting a
>bunch of 'exotic' circuitry in the critical path of the coil circuit to
>accomplish such a trivial task seems to me to be counter-productive. If you
>are counting milliamps then your system probably has bigger problems.
That philosophy is core to this product from Tyco
http://www.aeroelectric.com/Pictures/Contactors/Kilovac_EV200_c
which not only offers a sealed atmosphere environment
for better high voltage handling but an after-engagement
duty-cycle managed for reduced power consumption. But
it's about a $135 device as I recall.
One of the drivers for installation of the E-bus was
to eliminate the 0.7A draw of a battery contactor
during alternator-out operations. That much current
would run several radios . . . but might seriously
impact a design goal for battery-only endurance to
exceed fuel endurance. Trivial task? It's a matter
of degree . . .
Exotic? About $6 worth of Radio Shack parts
will do it and it doesn't increase risks. But
if one has a Rotax 18A or SD-8 excited airplane
the wasted watts become more critical than when
you've got 60A alternator with 40 to burn. So
one could choose to achieve similar performance
with a plain vanilla contactor and DIY duty-cycle
management.
Hardware capable of very fancy footwork is becoming
less expensive while consuming less power. The things
one could put in a 25 year-old VariEz lit up with
an SD-8 were very limited . . . not so much today.
It's all inter-related and as mentioned earlier,
related to mission, hardware, full up vs.
endurance loads, battery sizes and PM protocols.
So if latching battery contactor is more a
attractive than a duty-cycle managed device, you
are ultimately responsible for the formulation
of design goals and techniques used to meet them.
The basket of bits-and-pieces with which the big
picture is painted is huge . . .
Bob . . .
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