Just had a Collins radio die mid-flight at 30,000 feet

I was up on a King Air 350 last Wednesday doing a routine check on the Collins Pro Line 4 system. Everything looked fine on the ground, but about 10 minutes after takeoff (I was riding along to verify a squawk), the whole navigation display just went black. No flickering, no warning flags, just nothing. The pilot had to switch to the standby instruments and we turned around. Got it back to the hangar and found a failed power supply board in the main display unit. Took me the better part of 3 hours to isolate it with the multimeter and find a replacement part from our supplier in Phoenix. Has anyone else had a Collins unit crap out like that with no warning signs beforehand?

3 comments

3 Comments

william_henderson2mo ago

That power supply board failure sounds like a real headache. I had a similar thing happen on a Collins radio about 18 months ago in a Cessna 208. It was the audio panel that just went dead mid-flight, no static or warning, just silence. We traced it to a failed capacitor on the main board. After you swapped the board, did you run a full system test on the ground or just power it up and check for normal operation? I found sometimes those boards can look fine on the multimeter but have intermittent issues that only show under load or vibration. Did you bench test the old board after you pulled it?

hannahk1929d ago

Man, I gotta push back a little on the bench test thing... I mean yeah, it's nice to know what went wrong, but in my experience, if a board has already failed once in the air, I'm not spending hours trying to fix a 20-year-old power supply just to bench test it. I sent the old one back to the manufacturer and moved on. For intermittent stuff like hairline cracks though, I don't trust bench tests anyway - they just don't shake and heat cycle like a real flight does. I've pulled old boards that passed every bench test you can think of, then put them back in the plane and had the same failure on the next flight because the solder joint only flexed under real G loads or temperature swings. That's why I just power it up on the ground, check normal operation, and call it good enough... if it flies for a month without acting up, I figure the problem's solved.

rubyk862mo ago

Always bench test the old board if you can. I had one that looked perfect on the meter but started acting up again on the bench under a load tester. Took me forever to find it was a hairline crack in a solder joint that only opened up when the board flexed under vibration.