Trick I learned for chasing corrosion under floor panels

Been dealing with a tough corrosion spot under a floor panel on a Cessna 172 last month. Tried a few things that didn't work, then an older mechanic told me to use a brass brush wheel on a die grinder at low speed with some corrosion inhibitor. Problem was the corrosion kept coming back under the paint after cleaning. The brass brush wheel was gentle enough not to gouge the aluminum but got into the pitting better than sandpaper. After three passes and a careful alodine touch-up, it hasn't come back in six weeks. Anyone else use brass brushes for this or is there a better method?

2 comments

2 Comments

jake_walker1d ago

Kinda hesitant on the brass brush thing. I have seen those leave little brass particles embedded in the aluminum that can set up galvanic corrosion down the road if you are not super careful cleaning it off after. Maybe try a scotch-brite pad on a die grinder next time, or just some good old fashioned hand sanding with 320 grit and a block. The alodine touch-up is the key part though, that stuff really seals the deal if you get it clean enough.

seth_carr1d ago

Hell yeah, @jake_walker nailed it. I totally wrecked a window frame on a job once because I used a brass brush and didn't get all the little shavings off. A few months later there were these ugly black pits where the corrosion set in. I only use scotch-brite pads now, or even just a clean rag with some paint thinner. That alodine is a life saver if you can get the surface really bare and clean first.