Fuses on the panel, or not

In a recent safety bulletin from the FAA, they noted that inflight resetting of circuit breakers should mostly be avoided and that in any case they should only be reset once and thereafter left triggered if it happens again; delaying further troubleshooting until the flight is completed. They suggest the tripped circuit breakers, found during a pre-flight, should not be reset without investigation by airframe or avionic technicians.

Fuses are not discussed, but the principle of protecting the main electrical system from a failed sub-system still applies. If it occurs in flight, do your best to do without it for the remainder of the flight.

Recently I was powering up a PIK-20 and after a few moments there was a smell of burning insulation and I powered the system off. In the following inspection we discovered that the VolkLogger had shorted and the complete harness from the VL to the power distribution had basically melted. The circuit was protected by a 2 Amp fuse that did blow but I have to believe there was much more than 2 Amps flowing to melt that wiring before the fuse melted.

I'm just delighted that it didn't happen after I was aloft. I might have not smelled the burnt wiring if there had been some airflow through the cockpit. Might have lite something else up before I know it.

We are planning on rebuilding the whole panel/electrical system this winter and I'll do some serious measuring before selecting the fuse current values. I'd rather the fuse blew early that late.

Mike