Saw a radar unit arc out in the hangar last Tuesday - near miss

I was working on a King Air 200 at a small shop in Boise last week, swapping out a weather radar antenna. Everything looked fine on the bench test, but when I powered it up on the aircraft, I saw a blue arc jump from the connector to the housing. That thing could have fried the whole radome if I hadn't caught it. Turns out the pin on the coax had a hairline crack from a previous install where someone overtightened it. Took me 2 hours to replace the cable and reterminate it, but it beat explaining to insurance why a radar fire started. Anyone else run into bad coax terminations that looked fine but were actually arcing?

3 comments

3 Comments

wadejenkins11d ago

@paige_bell81 must have a gremlin hiding in her crimpers.

iris_barnes8712d ago

That line about "looked fine but was arcing" hit close to home. My buddy Dave had a similar thing happen on a Cessna 310 up in Spokane, where the coax looked perfect until he pulled it out and felt the insulation was slightly melted near the connector. He told me the arcing was so small he almost missed it, just a faint blue glow in the dark corner of the hangar. Took him forever to track it down because the multimeter showed continuity fine, but the crack only opened up when the unit was powered and vibrating a little.

paige_bell8112d ago

Brought back something I read in an old aviation forum about this guy who spent three days chasing an intermittent radio issue on a Piper Seneca. He finally found a hidden crack in the coax inside a bundle of wires, only visible when he bent it at a specific angle. Sounds like your buddy Dave's story with the Cessna was way more subtle though, @iris_barnes87.