Whistling Noise when the Master is turned on

I had that happen on my 1978 Toyota Celica. Turn on the headlights and a whistle started. I never figured out what was causing it but the alternator did fail not long thereafter.

Good Luck!

Wayne

I was out preparing for a flight in my 415-C. When I flipped on the master, a whistling noise lasting for about 3 to 5 seconds occurred. What does that mean? No issues with starting or smoke from the battery box.