The dreaded electrical Gremlins strike again!!

The breaker for the landing light is tripping. In a Mooney it is built
in to the switch and the switch will not stay on. I'm thinking that
there is a short somewhere but I don't know why that would cause the
whole avionics bus to go flakey...

Jon Kraus
'79 Mooney 201
4443H @ TYQ

Dan Luke wrote:

wrote:


From what you describe, the multisystem failure would tend to indicate
something in common. Possibly a shared breaker (avionics avionics
master), but most
likely a single-point, shared ground that's flakey.

Most GA aircraft are a multi-layered hodge-podge of crappy electrical
wiring.
In particular, grounds tend to be wherever the last boob to install it
had a pre-cut
wire long enough to reach. Having a single-point where everything
grounds is a good
thing to eliminate ground loops. Gotta make sure that one point is
solid, though.


Concur. Most likely it's not a short, which would pop a breaker. An
intermittent open or high resistance connection would fit the symptoms,
and the ground connections are the places to start looking.