Circuit Breaker Panel is getting hot

Suggest PTFE with wire gauge adjusted for amps under min voltage (then adjust again for margin according to automotive standards). ETFE/PTFE temp diff circa 110C if my memory is correct. Good reading here:

They told me to check the current draw on the thick lines. My maintenance shop did it and it was 7 resp 10 amp with air conditioner on (they were suspection the a/c). So it actually can't be an overload.

What you actually want to measure is the DC resistance of that line, it looks like a bad (high resistance) joint. 7 amps through one ohm is 49 watts of heat, 3 ohms produces 147 Watts etc.

Have you ever seen a UK 13 Amp mains plug burn up when the fuse holder oxidizes and produces a few ohms resistance!

It seems you have decided a radical and probably more long term solution.

However, diagnosis of this kind of thing is greatly aided by one of these

Thermal imaging cameras

That's a very good decision! Just be careful... there's many different "German Standards" too :-))

I agree, and to add that this department is safety-critical because some of the wiring is unprotected i.e. a short to the airframe and you probably have a fire. Only wires downstream of circuit breakers (or fuses) are protected from a short circuit.

Anyway, it is a great excuse to knock up a new CB panel, with nice custom engraved labels

Without having the knowledge Peter has I would say that this is such a sensitive area that I would not spare any expense to get this done perfectly. You do not want to fly a turbine aircraft with such a problem. This will probably cost you some money, but THIS is really worth it, I think

I can see why they might want to rewire the whole panel...

• revenue generation
• warranty liability (if you just fix one thing, and something else packs up?)
• the inline fuses are a bodge which has no place in an aircraft (they should be properly mounted CBs or fuseholders)
• the heat may be generated in multiple places
• there might be faulty CBs, with bad contacts which are generating heat

I would re-do the whole thing too.

Aircraft CBs are not the best quality products and do degrade over time; I think because they run pretty warm all the time anyway.