Pro tip: Talking to a 20 year A&P changed how I check bond straps

I was working on a King Air 200 last week at the hangar in Wichita and this old A&P named Dave walked by while I was testing a bond strap. He just shook his head and said 'you know you're wasting time if you're not checking the terminal ends for corrosion under the lug.' I'd been zapping those straps for years, passing them fine on the meter, but never once pulled the bolt to look underneath. Pulled one off and sure enough, there was white powder hiding under the washer. That little bit of corrosion was causing intermittent static on the nav radios, something I'd chased for two days last month on a different plane. Now I pop every bond strap terminal off at least once a year for a visual, and I haven't missed a gremlin since. Anyone else ever find something obvious hiding in plain sight like that?

2 comments

2 Comments

mila_jones395d ago

Dave showed me that trick on a 1980s Cessna 421 about fifteen years ago. He made me pull every bond strap terminal on the whole airplane, and I found three of them with that white powder hiding under the washer. The worst one was on the left engine mount, where corrosion had eaten a small pit right into the aluminum underneath the lug. We cleaned it up and put a fresh star washer on, and the intermittent compass error I'd been fighting for weeks just disappeared completely.

max3886d ago

Man that's a good catch. I had a similar thing happen on a Cessna 310 a few years back, chasing a weird glitch in the right engine gauges. Pulled the bond strap off the firewall and found corrosion hiding under the washer just like you said. The meter was showing good continuity but that little bit of gunk was causing all sorts of intermittent problems. It's one of those things that makes you feel like a dummy for not checking sooner, but you just don't think about it until someone shows you. Now I always tell my guys to pop those terminals off and look, it saves a ton of headache later.