On Jul 28, 9:10*pm, ContestID67 wrote:
I gave a presentation on this subject of avionics wiring at the 2007
SSA convention. *Seehttp://derosaweb.net/aviation/presentationsto
download the presentation. *It looses a little without my voice over
but you will get the main points. Darryl - Please critique this if you
get a chance.

Couldn't agree more on the use of tefzel. *It is an FAA requirement,
not an option. *I have seen lots of incredibly lousey glider wiring so
I am on a "jihad" to get the word out to do better. *Remember that
your local DIY or electronics store does *NOT* have an aviation
aisle. *http://wingsandwheels.com/page5.htmhas a good assortment of
Tefzel as well as places like Aircraft Spruce and Wag Aero.

Using rules of thumb on wire gauges can lead to mistakes. *Should the
main line from the batteries to the instruments be 12 gauge?
Smaller? *Larger? *It all depends on the load. *In a airplane (versus
an glider) this can go from little to massive, so determining the
gauge needs some careful analysis. *Luckily the load of the avionics
package in a typical glider is fairly standard (vario, computer/
recorder, PDA, transceiver) so 12 gauge is generally considered OK.
I haven't analyzed the typical loading of a transponder so cannot
comment further.

Other control (ptt, gear warning) and audio (speaker, microphone) are
low current affairs so I typically using 22-24 gauge which you can
find in multiple wire bundles.

Finally, my disclaimer. *I am *NOT* a FAA certified avionics
technician. *I cannot sign a log book for a repair or perform the
installation. *You need to get your work done by, or overviewed by, a
FAA licensed tech. *Nuff said.

My $0.02.

- John DeRosa

John, my only comment is I'd encourage people to look for the best
quality *ratchting style* crimpers they can afford - for both Coax and
for wire connectors. Using these tools often produce a night and day
difference from non-ratchting style crimpers, the cheaper ones of
which cannot possibly produce enough jaw pressure to create a correct
connection. The brand name ratcheting crimpers tend to be just better
engineered and the ratcheting mechanism helps ensure the correct
pressure is applied (as long as you use the right connector for the
wire gauge).

There is a good article on crimpers for use in aviation wiring at
http://www.aeroelectric.com/articles.html (and he is comparing an
already better ratcheting crimper than many people would use with an
even fancier one but the good thing is he is showing in detail what a
proper crimp joint looks like). That web site also has lots of other
interesting information and informed opinion on aviation electrics.

While none of this is rocket science by any stretch, I still worry
that if people are having to ask basic electrical questions then the
best thing may be to find an A&P who can show you how to do
professional wiring and look over your shoulder at your work. And to
get a really professional job it might turn out to be cheaper to pay a
trusted A&P to do it than buy special tools, a stock of Trefzel wire,
etc. I know finding that A&P may be the issue in many cases.

Darryl
(Just an anal retentive glider pilot/owner and electronics geek, and
not an A&P)