TIL the hard way that a 6-foot drop from a ladder stand can crack a composite panel clean through

Was swapping out a flap motor on a 2016 Cessna 172 last Tuesday and dropped my wrench, which bounced off the leading edge and left a 4-inch hairline fracture - has anyone else had to patch this kind of damage with just epoxy and a doubler plate?

3 comments

3 Comments

aliceharris2d ago

Whoa hold on, I have to disagree with using just epoxy and a doubler plate on a composite leading edge. That crack is on a primary structure and FAA rules are pretty clear about that kind of repair. You really need to follow the manufacturer's structural repair manual step by step, or you risk the panel failing in flight. A doubler plate might hold for a while, but vibration and load changes can make things worse over time. I've seen too many backyard fixes turn into big problems down the road. Better to get a certified repair done right the first time.

jana5092d agoTop Commenter

Have you actually tried doing a permanent doubler plate repair that held up for more than a year without issues? Because I have, and I'll tell you right now, it's a crapshoot. The problem isn't the epoxy itself, it's that you can't control how well the bond will hold up under the constant vibration and temperature swings of flight. I've seen those plates pop off at the edges where the stress concentrates, and then you're looking at a much worse crack that needs a whole new section. The manufacturer's manual is there for a reason, it's been tested and approved by the engineers who built the plane. Sure, it costs more to do it right the first time, but it's way cheaper than explaining to the FAA why your leading edge came apart mid-flight.

andrew_baker91d ago

@aliceharris lighten up. Ever actually seen a leading edge fall off from a doubler plate?