During my first multi lesson in a seneca I had a electrical fire in the electrical panel to the left, resulting in turning off the Mags to one engine. In the approach, the electrics totally failed when the gear went out, loosing the gear lights before going to all green. We did a go around (single engine), and played with the switches to get the greens back for landing on the next attempt. Cause was water overnight getting through the storm window.
Partial power at about 300ft after takeoff in a single engine, carb heat application didn't make things worse than the norm 150-200rpm drop as expected, and I managed to nurse it back around to land on the runway in the opposite direction. Cause was fuel contamination.
Heavy turboprop, engine stopped at night, 200ft after take off. Came back to land. Cause was a propeller control unit failure. Fortunately the aircraft type has a auto feather feature.
Heavy turboprop engine stopped just prior to top of descent, at night. Unfortunately for me the Captain wouldn't allow a relite attempt. Cause was about half the amps were getting through to the heating element in the air intake and there was a flame out from ice ingestion.