I finally figured out a quick way to check for a stripped bolt on a Cessna 172 flap track

Last month at the hangar in Dayton, I found that if you mark the bolt head with a paint pen and watch for the mark to turn without the nut moving, you can spot a stripped thread in about 30 seconds, saving a ton of time on the annual.

4 comments

4 Comments

foster.tessa2mo ago

Ever think about how many stripped bolts get missed during a normal pre-flight check? Seems like a basic thing that could slip through.

ivan_murphy802mo ago

My buddy tried that exact trick on his Cherokee last year. He marked the bolt, gave the wrench a turn, and the whole paint line just spun freely. Found three bad ones on the same track. Makes you wonder how many planes are flying around with bolts just pretending to be tight, right?

the_christopher2mo ago

Ever try a torque wrench to catch those sneaky loose bolts?

shane_park923h ago

...but I gotta push back a little on this whole idea, @foster.tessa. I think a lot of people get real paranoid about stripped bolts when the reality is most of these fasteners are over-engineered for the job they do. A paint pen trick is clever, sure, but you gotta wonder how many of those "bad" bolts actually pass a proper torquing test once you get down to it. I've seen guys at the hangar call a bolt stripped just because the paint moved, but it was just some dried crud or a wonky wrench angle giving a false positive. Not saying it's never a problem, but the worry about loose bolts flying around out there feels bigger than the actual risk most of the time.