Flashers seen at lake Elmo Airport

Saturday 04/25/10:

Sort of one of those "Man bites Dog" titles...

Well, the flashers were the strobes on the Apache. One of the strobes quit working. Knowing that the two are wired together from the same 12V supply via a breaker-switch, I figured the problem was the high voltage power supply (located in the wing) or the bulb itself and ordered one of each.

Just to make sure I wasn't going to extra work, I decided to measure the voltage to the power supply. It was a puzzling reading. Not zero, but not 12V, and wandering all over the place. To test the strobe, we supplied 12V right to the high voltage supply for the inop strobe, and it worked fine.

Hmmm... okay. It's NOT the power supply or bulb, but something in the wiring. I figured it was a bad splice, and replaced connectors I could find in the wing that looked ratty. I got 12V out, and though all was well. I plugged it back in, and... it didn't work! The same wonky voltage problem appeared again.

So, with some help with Jeff Hove and Patrick, we tried a few other things. We disconnected the right strobe, and plugged in the left strobe. It worked. We tried the opposite, and the opposite strobe worked. We tried both, and only the right strobe works. Clearly it can't power both strobes.

I suspect a bad breaker-switch. To get to the switch and jumper across it to verify the problem, a bunch of stuff has to be taken out, so I figure I'll have another switch on hand to replace it if it's bad.

I have one other hunch that I'm going to investigate. The instrument panel dimmer rheostat is right near where the strobe switch is. Is there any chance that when the radios were redone they accidentally hooked the strobe supply to the output? It would act very strange if not in the "full on" position, and wouldn't be something a person would notice right away. I'll check that out before I rip things apart.

There are no easy days in aircraft repair! :-)

_Paul