Had to pick between fiberglass and carbon fiber for a flap repair, chose wrong at first

Was patching up a Cessna 172 flap last Tuesday and the shop had both fiberglass and carbon fiber cloth in stock. I grabbed the carbon fiber because it felt tougher, but my lead mechanic stopped me and said it can cause galvanic corrosion against the aluminum spar if the layup isn't perfect. Swapped to the fiberglass, took an extra 20 minutes to sand and prep, and the repair held up fine during the test flight. Anyone else ever made a material choice that bit you later?

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1 Comment

wood.john23d ago

Whoa, wait, galvanic corrosion? That's a big deal. I've heard of that issue with carbon fiber and aluminum on boats, but I never thought about it happening inside a flap like that. Good thing your lead caught it before you buttoned everything up. That would've been a nasty surprise a few months down the road when the spar starts eating itself. I bet a lot of guys don't even think about that when they're just grabbing whatever cloth is on the shelf.