Today's Message Index:
----------------------
1. 12:39 AM - ELT antenna location (Chuck Birdsall)
2. 06:28 AM - Re: #2 Welding Cable (Ben)
3. 07:38 AM - Re: ELT antenna location (Bill Putney)
4. 09:15 AM - Z14N incorrect switch designation? (Jay Hyde)
5. 02:09 PM - Re: Z14N incorrect switch designation? (Robert L. Nuckolls, III)
Message 1
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Subject: | ELT antenna location |
I'm putting a 406MHz ELT (ACK E-04) in my Piper Cherokee in place of
dead OE Narco.
One of the statements in the installation manual - and in other
references such as AC43.13-2 and antenna manufacturers - says that the
ELT antenna should be at least 36 inches from a Com antenna. Key word:
Should.
The original mount for the factory-installed Narco ELT antenna is 18
inches away from the Com 2 antenna. A quick cruise around the airport
found that most of the Pipers with dual coms have a similar setup. I
don't want to move the Com 2 antenna because that will start a vortex
I'd rather avoid for the time being. Venerable but still functioning
avionics package supported by an antenna farm limits my options.
I realize there are coupling factors with antennas placed within a
half-wavelength of each other. I called the manufacturer and asked -
and was told they strongly recommend maintaining 3 feet distance, but
they also shoved lots of RF at the antenna/ELT combo during testing and
saw no ill effects.
So the questions are:
Am I going to have to move the Com 2 antenna?
What are the risk factors if I leave the antenna locations as they are?
Thanks,
Chuck
Message 2
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Subject: | Re: #2 Welding Cable |
Personally I agree with Bob...... If you have a fire burning to the exte
nt of worrying about fumes coming off the insulation jacket, you have yo
ur priorities wrong.......
Ben Haas
N801BH
www.haaspowerair.com
---------- Original Message ----------
From: robert wiebe <ramjetwiebe@yahoo.com>
Subject: Re: AeroElectric-List: #2 Welding Cable
Please, can I say something?
My first comment may be, "What doesn't produce noxious fumes when it bur
ns?"
Well, a goodly amount of welding cable, it seems. It just doesn't burn.
Some does. One insulation for welding wire is treated neoprene rubber. I
remember some time ago (when I was a chemical rep) there was a big disc
ussion on the use of ETU (Ethylene Thiouria sp?) as it was used in the v
ulcanization process. (There may be other methods in use now.) And neopr
ene rubber burns.
EPDM does not.
BTW, both come in red and I can't tell you why so few use this colour on
their + battery runs.
What is not supposed to burn is EPDM. Ethylene propylene diene monomer
is, I think, the most common store bought welding cable insulation. The
price for a brand name is roughly the same as for neoprene. However, I (
that would be me but you have your own choices to make) would not use EP
DM in this application as it has significantly lower resistance to greas
e and oil than neoprene. Apart from that, EPDM and neoprene are pretty m
uch equal in strength, abrasion resistance and so on so FFW I would have
no temptation to use EPDM - except that EPDM is not supposed to be flam
mable. Much of the surplus welding cable I have encountered seems to be
neoprene, but I wouldn't count on it. (They both come in different colou
rs and finishes.) So, with EPDM, no poisonous fumes. It doesn't burn. Pu
t that in your pipe and try and smoke it!
The neoprene cable I am most familiar with is the Carol Brand made stuff
(now General Cable.) General Cable makes even more rugged wire, but I h
ave never seen it in use - only on sample boards. In the spec sheets, GC
calls US made Carolprene flame resistant. The big welding stores sell t
his stuff by the light year.
I do know that Carolprene finds its way inside mines, factories, etc. wh
ere there are going to be major concerns in the case of fire. I have bee
n around this or similar products most of my life and have never seen it
burn. Granted, I have never intentionally taken a torch to the stuff bu
t I can tell you it exists in seriously harsh environments. (It pulls ba
ck if you solder it with a torch so I learned to make good crimps. That'
s one expensive(!) crimper [so borrow] but I was always able to find goo
d terminals surplus. DKW.)
Next time I see a wire rep, I'll ask if he can give me the burn temperat
ure for the insulation. A brief hunt http://msds.dupont.com/msds/pdfs/EN
/PEN_09004a35803d9eb8.pdf reveals that plain ol' neoprene "burns" (flash
point, open cup) at above F500 (C260) degrees. For reference, wood burns
at about C300 degrees. The fumes from neoprene ARE toxic and noxious. T
hey can cause permanent lung damage.
Even though EPDM is NOT flammable it's maximum listed service temp is C1
50 degrees. So if you want, run as much as you like inside your aircraft
and dare your buddies to burn it. Under the hood, EPDM does find it's w
ay into ignition wires, but to my mind this is an item you replace every
annual. If you build nose heavy and put your battery(s) in the tail, th
en this might be just the place to run EPDM!
More importantly, I think, than insulation is wire strand size. I have s
een a LOT of very heavy strand stuff called welding cable even though it
would never be tolerated. Acceptable stranding should be no larger than
0.010. All the good stuff is.
In addition to Bob's comments about fusing: I guess you could always put
in a fusible link if you REALLY felt the need. This just seems like an
additional and unnecessary failure point (more connections) to me. I wou
ldn't do it. ( Aside: As a teen, I had a '74 Mazda Rotary with a failed
fuse link that took me days to find. They also ran all the current throu
gh the ammeter; something I learned not to do thanks to that experience.
)
In the one aircraft I have built and the two projects I am working on, I
installed a cable or rod operated mechanical battery switch and no sole
noid. (A switch needs no current to stay on.) Either way, I don't know i
f I would remember to turn off an ignition switch or flip a battery swit
ch (and turn off the fuel and turn off the fuel pump and so on) if I was
in a hurry to get out of the way. Maybe that requires practice on my pa
rt. I remember reading a tale of a WW2 pilot who bailed out and felt che
ated at just that moment as in all his training they never even gave him
a minutes instruction - let alone practice - on how to deplane ("Not no
w, Tatoo. I'm busy admiring the Corinthian Leather seats in my Volare."*
) when he wasn't on the ground.
All this conversation about safety... How many of us wear a parachute?
*"De plane, Boss! De plane!" If this makes no sense to you, I feel very
old.
Neoprene does not appear to be a trademark, hence I avoided capitalizat
ion as it is a generic term.
-Robert
From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
Sent: Sunday, June 23, 2013 6:55:03 AM
Subject: Re: AeroElectric-List: #2 Welding Cable
Bob,
Do to W&B considerations I am moving my 2 Panasonic 1220 batteries 8' af
t. I had originally used #4 as the runs were all short, 18" or less(all
forward of the firewall). The batteries were initially mounted on the fo
rward firewall.
As the cable runs are now 9' I intend to use #2 welding cable. Yesterday
another builder stopped by to "review many progress" and said welding c
able might not be a good choice aft of the firewall as welding cable giv
es of poisonous fumes if it burns.
Comments?
When ANY insulation burns, the products of
combustion are exceedingly unfriendly
to children and other living things.
There are folks who make it their life's
work to 'reduce risk' . . . even to the point
of codifying their profundities and threatening
you with retribution for regulatory
transgression.
In THIS case: What conditions would cause the
insulation on these cables to burn? Electrical
overload is one . . . externally applied fire
is the other.
The risks for electrically induced overload are
so tiny that certified iron of all sizes does
not add overload protection to these wires.
In FAR23.1357 we find these words:
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.
If you've got active fire in the aircraft
that threatens to ignite your wire's insulation,
then I suggest your risk issues go far beyond
any concerns for the quality of the smoke.
Bottom line is that while those-who-know-more-
about-airplanes-than-we-do will prohibit certain
insulations in new design, they still permit
an older airplane to be repaired with the SAME
insulations that were on the original type
certificate.
For example, a 1946 C-140 wired with cotton over
rubber wire or a 1968 C-172 wired with nylon over
PVC can be repaired with the same wire. If the
admonitions for controlling cockpit pollution
were imperatives, then one would think that any
airplane brought in for repairs should be
completely re-wired.
The short answer is that risks to your future
well being due to poor selection of insulation
are vanishingly small compared to risks
for bird strike, wind shear . . . or running
out of fuel.
Bob . . . lank" href="http://www.matronics.com/Navigator?AeroElectri
c-List">http://t; http://www.matronics.com/contrib========
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Message 3
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Subject: | Re: ELT antenna location |
You're going to have to replace the factory ELT antenna anyway. The 406
ELTs come with antennas that work on both 121.5 and 406. The old antenna
will only be effective on 121.5. Are you saying that you have to move
the Com 2 antenna because there's no place on the upper fuselage that's
3' away? Or are you saying you don't want to move the ELT antenna position?
In any case, the biggest problem of having the 2 antennas in such close
proximity is going to be that they will influence each others radiation
patterns and you'll find nulls in the coverage in certain directions.
I'm a little surprised that the antennas got positioned that close to
begin with but it's hard to find enough good places on small airplanes.
Bill
On 6/24/13 12:38 AM, Chuck Birdsall wrote:
> <cbirdsall6@cox.net>
>
> I'm putting a 406MHz ELT (ACK E-04) in my Piper Cherokee in place of
> dead OE Narco.
>
> One of the statements in the installation manual - and in other
> references such as AC43.13-2 and antenna manufacturers - says that the
> ELT antenna should be at least 36 inches from a Com antenna. Key
> word: Should.
>
> The original mount for the factory-installed Narco ELT antenna is 18
> inches away from the Com 2 antenna. A quick cruise around the airport
> found that most of the Pipers with dual coms have a similar setup. I
> don't want to move the Com 2 antenna because that will start a vortex
> I'd rather avoid for the time being. Venerable but still functioning
> avionics package supported by an antenna farm limits my options.
>
> I realize there are coupling factors with antennas placed within a
> half-wavelength of each other. I called the manufacturer and asked -
> and was told they strongly recommend maintaining 3 feet distance, but
> they also shoved lots of RF at the antenna/ELT combo during testing
> and saw no ill effects.
>
> So the questions are:
> Am I going to have to move the Com 2 antenna?
> What are the risk factors if I leave the antenna locations as they are?
>
>
> Thanks,
>
> Chuck
>
>
Message 4
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Subject: | Z14N incorrect switch designation? |
Hello Bob,
I am modifying the Z14 architecture for Rotax type generators/ dynamo's; it
seems to me that the STARTER/ CROSS FEED switch should be a 2-5 (ON)-OFF-ON,
rather than a 2-7 (ON)-OFF-(ON)?
Jay
Message 5
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Subject: | Re: Z14N incorrect switch designation? |
At 11:08 AM 6/24/2013, you wrote:
>Hello Bob,
>
>I am modifying the Z14 architecture for Rotax type generators/
>dynamo's; it seems to me that the STARTER/ CROSS FEED switch should
>be a 2-5 (ON)-OFF-ON, rather than a 2-7 (ON)-OFF-(ON)?
>
>Jay
>
>
You are correct. The schematic symbol is correct but
the p/n callout wrong. I'll fix. Thanks!
Bob . . .
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