A trick for chasing down a phantom voltage drop I learned from an old guy at a hangar in Phoenix
I was stuck on a King Air with a weird nav light issue, showing 10.8 volts at the lamp when it should have been 14. I was about to start pulling panels when this retired guy, Frank, who was just hanging around, asked if I'd checked the cannon plug shell. He said, 'Kid, the airframe is the ground path, but corrosion loves to hide where the plug meets the metal.' I cleaned the plug shell mating surface with a scotch-brite pad, and the voltage jumped right up to 13.9. It's saved me hours since. What's your go-to method for finding a bad ground on older airframes?