Rewiring whole plane, should I follow original scheme?

sanships · Post by **sanships** » Sun Jul 24, 2005 5:36 am

I will be rewiring the whole aircraft. What are your thoughts on the original wiring layout and hardware. What should I upgrade and what is best to be left alone? I am adding strobes and an engine monitor plus digital radios and transponder only so I'm inclined to just rewire using the original layout. Any recommendations as to what type of wire to use? Thanks!

Post by **GAHorn** » Mon Jul 25, 2005 1:50 am

Use the original layout and routing, and use the original attaching/securing points. (Why re-invent the wheel,...and risk a mistake with an untried method?) Just use modern, aircraft "TefZel" wiring that meets current MIL-Spec. (MIL-W-22759/16)
Knowing that you are also dealing with avionics issues, consider that newer coaxial cable (antenna wires) are no longer made from the old RG-58U. It is made from RG-400U, which is MUCH better.
Follow "acceptable methods and practices". Use the correct crimp connectors (aviation...not automotive....and don't solder connectors because they weaken the joint due to increased vibratory stress, etc.)

blueldr · Post by **blueldr** » Mon Jul 25, 2005 2:24 am

If you're into a serious rewiring, now is the time to get rid of those off breed fuse holders and install circuit breakers. There is nothing wrong with fuses to provide protection, but those 5/16" diameter fuses are a real S.O.B. to find when you really need one.

Post by **GAHorn** » Mon Jul 25, 2005 2:41 am

blueldr wrote:If you're into a serious rewiring, now is the time to get rid of those off breed fuse holders and install circuit breakers. There is nothing wrong with fuses to provide protection, but those 5/16" diameter fuses are a real S.O.B. to find when you really need one.

Good advice, Dick, but the fuses are readily available from Hill Aircraft, http://www.cessnaparts.com/ as discussed elsewhere in these forums.

blueldr · Post by **blueldr** » Tue Jul 26, 2005 2:05 am

Hill Aircraft is a fine organization and a pleasure to do business with. They are in Georgia. When you have blown all of your fuses while trouble shooting the com nav system in Cour d'Alene, Idaho and you want to get on home, Hill Aircraft is not as handy as the local NAPA store that has 1/4" dia. glass fuses of all amp. ratings. If you run out of spare 5/16" dia. fuses , you're dead in the water.
Besides that, the damn things are grossly over priced, and they gouge the hell out of you when you need one. Only an insanely dedicated purist would even consider a rewiring job that retained thatbit of rediculous originality.

Be advised that I, the Blueleader, have spoke!

cessna170bdriver · Post by **cessna170bdriver** » Tue Jul 26, 2005 3:11 am

blueldr wrote:Only an insanely dedicated purist would even consider a rewiring job that retained thatbit of rediculous originality.

Be advised that I, the Blueleader, have spoke!

Dick,

I love your skill at NOT beating around the bush!

Miles

PS: I threw '98C's fuse panel in the junk box around 1988 or '89.

Post by **GAHorn** » Tue Jul 26, 2005 5:05 am

blueldr wrote:Hill Aircraft is a fine organization and a pleasure to do business with. They are in Georgia. When you have blown all of your fuses while trouble shooting the com nav system in Cour d'Alene, Idaho and you want to get on home, Hill Aircraft is not as handy as the local NAPA store that has 1/4" dia. glass fuses of all amp. ratings. If you run out of spare 5/16" dia. fuses , you're dead in the water.
Besides that, the damn things are grossly over priced, and they gouge the hell out of you when you need one. Only an insanely dedicated purist would even consider a rewiring job that retained thatbit of rediculous originality.

Be advised that I, the Blueleader, have spoke!

But, Dick,....I already have the circuit breakers! What do I do with the empty spare fuse holders on the inside of my glove box door?

(Flight Instructor hat on:)
Anyway, why are you continuing to replace fuses that keep blowing instead of fixing the reason they are blowing?
Familiarity breeds contempt. Don't let these little airplanes lose your respect. They are fully capable of killing you. (You're only supposed to replace the fuse or reset the breaker once....and if it does it again you should have the cause found and fixed. It is not prudent to continue to replace fuses in a circuit that repeatedly blows them. If the reason is not found, then leave the fuse out or CB pulled if it's necessary to fly the airplane. It's not OK to keep replacing fuses that keep blowing and fly it home anyway even tho' the cause is unknown. Isn't that some kind of warning that there's an electrical problem? As for me, I'd be a lot more inclined to fly without a radio than fly with one that might start a fire.)
Blu eldr is correct, ...circuit breakers are better if you are doing that much re-wiring and can afford them and the panel remodeling. (keep in mind that the buss bars behind the panel attach directly to those fuse holders and the remodel job is not the simplest thing you'll ever do.)

cessna170bdriver · Post by **cessna170bdriver** » Tue Jul 26, 2005 1:03 pm

gahorn wrote: ...circuit breakers are better if you are doing that much re-wiring and can afford them and the panel remodeling. (keep in mind that the buss bars behind the panel attach directly to those fuse holders and the remodel job is not the simplest thing you'll ever do.)

You don't have to change the panel any whatsoever, at least in a later B-model (I can't speak for the earlier models.) Just replace the angle that holds the fuses with one drilled to hold whatever style of circuit breakers you select. The face of the angle that holds the breakers should wide enough so there will be room under the attach nuts for labeling.

Select a circuit breaker style with screw terminals, and drill a length of 0.5 wide by .050 copper strip to accept the screws along the bottoms of the breakers. Voila! a bus bar. The cross sectional area of this strip falls between an AWG-6 and AWG-5 and will carry a full load from a 60-amp alternator.

Install the angle assembled with breakers and bus bar in the identical manner and location (under the lip of the instrument panel) in which the fuse panel was installed. Add the appropriate size crimped ring terminal to the downstream wiring and you are ready to go.

Whether you select toggle, pust-to-reset, or push-pull breakers, make sure they are "trip-free" which means the breaker will interrupt the circuit, even if the actuator is held in the "on" position. I built mine with toggle-type, and replicated the same functions that were on the old fuse panel.

I also built a second panel (angle) with push-to-reset breakers for the radios (one breaker per unit), and wired its bus bar to the downstream side of the original "RADIO" switch (avionics master).

I hope this doesn't violate too many "standard practices". The AI that did the paperwork for my Jasco alternator installaton simply added a line stating "Replaced fuses with circuit breakers" to the 337. It has passed the scruitiny of three AI's at 15 annual inspections since then.

Miles

dacker · Post by **dacker** » Tue Jul 26, 2005 11:04 pm

Alvin, I am suprised no one has mentioned that if you rewire and re circuit breaker that you will need to choose the cb size to fit the max amp rating for the wire and the wire will have to be sized for the load (as well as the length of run). There are charts that show the acceptable sizes for a required load. I believe that is what George was alluding to when he mentioned following "acceptable practices".
I recently rewired my airplane and wound up with a bag full of automotive, and household wiring and connectors that was pretty scary. What I have now is neat, legal and much easier to work with.
Good luck!
David

blueldr · Post by **blueldr** » Wed Jul 27, 2005 4:01 am

In regards to the little spare fuse holders on the back side of the glove box door, I have modified mine to carry (in the event of a real serious emergency) condoms. Who knows when a comely
passenger may express a burning desire to become member of that well known club in the sky above 5280 ft.
Initiation in my airplane, without an auto pilot, can be really,really exciting.

dacker · Post by **dacker** » Wed Jul 27, 2005 9:56 pm

JUST IGNORE...JUST IGNORE....JUST IGNORE