Curious for your thoughts since the mechanic is closed today. Last night I took my 68 M20C out for the first night flight. I wanted to be by myself since I've already found a number of things that need to be fixed in daylight hours! Everything pre-flighted fine and off I went. On my second approach to landing, all three of my light toggle switches simultaneously flipped off on short final. I was only on the yoke and throttle at the time. Safe landing and tried to pop the landing light back on the runway to no avail. During taxi back to tie down I was able to get all of the lights back on and they stayed on until shut down. My radios and transponder worked normal and the electric fuel pump worked fine as well. No over voltage light (but it's never illuminated so it could be burned out) and amps were fine once I was able to get light on the instrument. No popping, crackling, or electrical burning smell.
The flight lasted a total of 25 minutes from crank up to shut down. It was a warm summer evening but nothing ridiculous. As I research online and play the scenario back in my head, I'm almost wondering if the lights overheating would cause this problem? No circuit breakers blew but I understand these toggle switches act as a circuit breaker as well. The fact they would not switch back on immediately but did within a few minutes of failure prior to shutdown leads me to believe whatever that was too hot had cooled enough. If I had an overloaded circuit I imagine I would have experienced the issue sooner than 20 minutes, loose wire or ground would show intermittent issues instead of all 3 immediately shutting down?
I had left my landing light on the entire flight due to staying in the pattern. I had not been adjusting anything electrical after my run up, just power adjustments. Since my landing light is old school, my initial guess is it got too hot and blew my circuit but I am open to hearing your opinions as my electrical expertise usually involves shocking myself. Needless to say, no more night flights until this gremlin is fixed!
Thanks