Today's Message Index:
----------------------
1. 04:03 AM - Re: Z19RB Fat wire protection, etc. (Robert L. Nuckolls, III)
2. 02:03 PM - Crimp terminals with built-in shrink (Robert L. Nuckolls, III)
3. 04:23 PM - Re: Squeal PTT (Paul McAllister)
4. 09:11 PM - Static in radio reception (Jeff Page)
5. 09:54 PM - Re: Choosing Z-Diagram base (Ed Holyoke)
6. 11:19 PM - Prestolite vs B&C (Allan Aaron)
Message 1
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Subject: | Re: Z19RB Fat wire protection, etc. |
At 09:44 PM 11/12/2008 -0600, you wrote:
>
>Okay Bob,
>
>Airplane and configuration:
>RV7 w/Eggenfellner Subaru H6 up front.
>2 PC625 batteries in the very back of fuselage wired per Z19RB.
>Fat wire (#4 CCA from Eric Jones) runs from battery contactors to a firewall
>"pass thru stud" (West Marine). Firewall side of the stud has 2 connectors:
>one to an ANL on the way to a 75A IR alternator (supplied with engine
>package); another to the starter solenoid mounted as part of geared starter.
>I think this is all in accordance with Z19RB architecture.
>
>My question concerns the cockpit side of this "pass through stud". Could
>you please reassure me that I am correct in planning a #6 wire from that
>same stud (as the fat wire is connected to) to the MAIN POWER DISTRIBUTION
>BUS (approximately 42 inches "as the wire goes") withOUT any fuse/breaker
>protection?
That's correct.
>Your picture:
>http://www.aeroelectric.com/Pictures/Wiring_Technique/A36_Firewall_B.jpg
>(cert. plane of course) shows a bunch of ANL's to avionics, etc., but in the
>OBAM world I guess we do not need to imitate that kind of installation?
I've never paid much attention to the fuse-patch on
the A36. Just pulled up the wiring diagrams. That airplane
has a variety of busses on the left cabin wall (c/b panel)
pilots switch panel (switch breakers), copilots switch
panel (miniature push-pull breakers), two alternators, etc.
This is a mechanically busy architecture that I hope will
never be implemented in an RV! The designers no doubt found
it necessary to worry about failure modes grown out of
complexity.
>And could you also point me to the reference in AEC that speaks to the lack
>of a need for ANL protection of the fat wire at the batteries? I think I
>have read that ANL's are not needed by the batteries but can not remember
>where I read that.
It's a convention that has been with us for a long
time. Fat-wire feeders in small aircraft have never
benefited from circuit protection due to the nature
of the exceedingly rare, soft faults these wires
experience. By "soft fault" I'm referring to a condition
that will NOT product the hundreds of amps in current
flow necessary to open an ANL or similar device.
I've seen soft faults that parted elevator control
cables while never causing a light to flicker, no
smoke or bad smells, yet the feeder in question was
protected by a 40A breaker in a 28v aircraft! These
tend to be very high, total energy events delivered
in small packets over long periods of time. The FAA
acknowledges this in the crafting of FAR 23.1357 which
I quote . . .
Sec. 23.1357 Circuit protective devices.
(a) Protective devices, such as fuses or circuit breakers, must be
installed in all electrical circuits other than--
(1) Main circuits of starter motors used during starting only; and
(2) Circuits in which no hazard is presented by their omission.
(b) A protective device for a circuit essential to flight safety may not be
used to protect any other circuit.
(c) Each resettable circuit protective device ("trip free" device in which
the tripping mechanism cannot be overridden by the operating control) must be
designed so that--
(1) A manual operation is required to restore service after tripping; and
(2) If an overload or circuit fault exists, the device will open the
circuit regardless of the position of the operating control.
(d) If the ability to reset a circuit breaker or replace a fuse is
essential to safety in flight, that circuit breaker or fuse must be so
located and identified that it can be readily reset or replaced in flight.
(e) For fuses identified as replaceable in flight--
(1) There must be one spare of each rating or 50 percent spare fuses of
each rating, whichever is greater; and
(2) The spare fuse(s) must be readily accessible to any required pilot.
For the purposes of this discussion, paragraphs (a)(1) and (a)(2)
apply. I might point out also that our implementation of fuse-blocks
in a failure tolerant system design also meets the spirit and
intent of the rest of 23.1357 as well. If your system is failure
tolerant, then there are no single systems "critical" to safe
operations and termination of flight. If your fuse panels are
not accessible to the crew, then no spares need be carried
aboard the aircraft.
>Thanks for all you do, Bob.
You're most welcome sir.
Bob . . .
Message 2
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Subject: | Crimp terminals with built-in shrink |
At 12:30 PM 11/10/2008 -0600, you wrote:
><nuckolls.bob@cox.net>
>
>At 09:42 AM 11/10/2008 -0800, you wrote:
>>
>>Hey all -
>>
>>I'm sure the Connection mentions something about this, but I don't
>>have it in front of me (i should know better than to leave it at
>>home!) and as I was getting ready to order some shrink tubing, I ran
>>across these crimp connectors with shrink tubing already on them.
>>They're
>>here: http://cableorganizer.com/heat-shrink/heat-shrink-connectors.html
>>
>>What's the deal with these? Are they awesome? If not, why not?
>>Also, is there a recommended material type for shrink tubing? Sorry,
>>I feel like I could be looking these things up in the Connection, but
>>as I said, I'm sitting here daydreaming instead of working. :)
>>
>>any help would be appreciated!
>
> You won't find them in the book . . . for several reasons.
> These are but one example of many that are offered in
> the marketplace and I have no personal experience with
> them or knowledge about them. I've tried similar products
> from various sources over the years and discarded all of
> them. They tended to be bulkier and/or less secure in the
> wire grip than the PIDG butt splices I stock and use most.
> These are a bit different so I'll get some, see what
> they look like installed and how well they work. Two
> packages of 50 pcs + shipping comes to $37 so they're
> 37-cents each at this quanity.
>
> They tend to be expensive on a joint-for-joint basis
> compared to simply adding heat shrink to less expensive
> or more compact techniques. I can't tell you that these
> particular products are bad or to be avoided. But you'll
> need very few of them to assemble your airplane. In
> terms of performance, they'll work no "better" than
> the process described here:
>
>http://www.aeroelectric.com/articles/PM_Solder_Sleeve/PM_Solder_Sleeve.html
>
> I'll give them a try and report back.
I received my order for splices cited above. The splices for
20 to 12AWG wires can be installed with our favorite el-cheeso
crimp tool.
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=97420
The shrink tubing has good shrink ratio and does feature
a dual-wall sealant that manages to come down sufficiently
tight on the M22759 Tefzel (smaller diameter than most
automotive wires).
http://aeroelectric.com/Pictures/Terminals/Krimpa-Seal_Butt_Splice.jpg
I was unable to deliver consistent crimps on the 22-24AWG
splices with any tools I have. I note that the supplier does
offer a tool tailored to the product . . .
http://cableorganizer.com/heat-shrink-crimping-tool/
. . . but the price is disappointing.
The finished splices have about the same bulk as the
legacy PIDG window splices at about 2/3 price per
splice.
Assuming your tool of choice produces an adequate crimp,
these devices perform as advertised.
Bob . . .
Message 3
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Hi Allan,
I called LightSpeed and the worked on them at no charge to address the problem.
I can't say that it was completely fixed, but it improved them to the point
of making them usable.
In a weak moment at AirVenture I bought some Bose for my airplane and they work
without any issues. I had buyers remorse for some time due to the cost of them,
but they sure are nice.
Cheers, Paul
________________________________
From: Allan Aaron <aaaron@tvp.com.au>
Sent: Wednesday, November 12, 2008 10:15:49 PM
Subject: RE: AeroElectric-List: Squeal PTT
Yes - my pilot headset is a Lightspeed. I didn't try
a passive one - but will do that on the weekend. Did you solve the problem or
are you just using conventional headsets now?
Allan
Message 4
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Subject: | Static in radio reception |
A friend of mine is flying a Citabria. It is quite new, but suffered
in a crash. I was completely rebuilt/restored and is now again a
beautiful airplane.
It has one snag. Perhaps folks on the list have some ideas. The
symptom is that sometimes radio reception is unreadable. Scratchy
static overwhelms the voice audio. It is most obvious when within 5
miles of the control tower, since it is necessary to ask the
controller to repeat multiple times. Other times, aircraft from over
100 miles away are heard on common frequencies, or the controller is
clear, so sometimes the receive works very well.
Transmit is believed okay. The tower never complains about
transmissions, but this has never really been checked over greater
distances than 10 miles.
The radio is a new Garmin, which was swapped for a few days with an
identical model, which exhibited the same symptoms.
Consultation with the factory has yielded little. Mechanics have
checked phyical connections and continuity, and cut the fabric under
the antenna so the ground doesn't rely entirely on the screws. He has
tried different headsets.
The ground plane is a piece of aluminum about 6" wide and 15" long on
the back of the aircraft where the ELT antenna is typically installed.
There are about 8 wires, tied together and attached to the ground
plane about 4" ahead of the antenna, and these wires wrap down around
the fuselage to extend the ground plane. The ground plane is also
electrically connected to the steel fuselage tubing. This is all per
factory instructions. There are no adjacent antennas, and this
antenna is at least 4 feet ahead of the tail.
Reportedly, a VSWR test at the antenna gave a poor result, but I was
not involved in the test and I am not sure about the reliability of
the equipment or the person doing the test. The antenna is a new
Comant, with COM and GPS.
Most of the things I can think of being wrong would likely affect
transmit more than receive and not produce static.
I am currently thinking that perhaps the radio, antenna etc. are
actually fine, but are intermittently being interfered with.
I have suggested to the owner that when the problem occurs, he try
powering off the new PS Eng audio/intercom, which then gives him a
direct connection to the radio. I also suggested he power off the
transponder. If that fails to help, I have loaned him a new antenna
(I will be a while building yet) to try.
If that doesn't help ... ???
Does anyone have any other ideas that should be looked into ?
Thanks !
Jeff Page
Dream Aircraft Tundra #10
Message 5
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Subject: | Re: Choosing Z-Diagram base |
We found a way to not have any electrons for keeping the engine alive.
Easy enough not to have our problem, but very critical that you do it
right. The fat wire from the battery to the contactor shorted out on a
brake line and filled the cabin with smoke. Shutting off the master
didn't help since it was downstream of the short. Dragged the battery
down to 5 volts. We do have one magneto and that's what kept it running
long enough to get on the ground. Very, very important that this wire
not be allowed to short, especially if both of your ignitions are on it.
Pax,
Ed Holyoke
Robert L. Nuckolls, III wrote:
> <nuckolls.bob@cox.net>
>
> At 03:07 PM 11/12/2008 -0500, you wrote:
>>
>> I am building a system which will contain a Lycoming 360 with dual
>> electronic ignition and one alternator.
>>
>> I have looked at Z-12, Z-19 and Z-28 as an addendum.
>>
>> Which one or combination of these diagrams would support a good
>> solution? I read somewhere in the pages that dual electronic ignition
>> would best be served by two batteries.
>
> . . . that statement is pretty old . . . when folks
> were still installing a lot of vacuum pumps. Do you
> plan a vacuum system or all electric?
>
> If all electric, have you done a load analysis to
> see how much power you need for comfortable completion
> of flight with the main alternator out? You mentioned
> Z-12 but consider also, Z-13/8. This is an exceedingly
> light and inexpensive way to make sure you have electrons
> to keep an engine running. I suspect you can trim an
> e-bus load down to 8A or less. Keep in mind too that
> you don't need to run both electronic ignitions all
> the time. During alternator-out operations, you can
> drop to one ignition with very little loss of performance
> which still holds a second system in reserve.
>
> Bob . . .
>
>
Message 6
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Subject: | Prestolite vs B&C |
After going to a lot of trouble to get the weight of my Mustang down I'm
running out of options to get my CG further forward. The only solution
I can think of is taking off my B&C starter and re-installing the
original Prestolite starter which I guess weighs about 10-15lbs more
than the B&C. Assuming it will fit in my cowling, are there any major
disadvantages (advantages?) in using the Prestolite. Thanks. Allan
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