Bits and Pieces
Builders' Tip - Reducing a Dent
By Ian Brown, Editor - Bits and Pieces, EAA 657159
Dents in aircraft skins won't necessarily prevent you from flying, but they do look ugly. Gus Funnel of Van's Aircraft says one way to at least get them to look a bit better is to reinforce them from behind. We all know that once stretched, aluminium skins will not "unstretch," but given the expense and work involved to replace a whole skin for the sake of a dent, this tip seems to have some merit.
Basically the idea is to take a piece of angled aluminium, or whatever channel is used for your stringers, and cut a length somewhat longer than the dent you are planning to stabilize. After tapering the ends, you drill, deburr, Cleco, and rivet the piece in place in an attempt to at least flatten out the ugly dent.
You will recall that we discussed the editor's major rebuild of his RV-9A. The forward-side fuselage skins are a major undertaking to replace, and the damage to them is relatively minor. We will at least give this a try and report on progress in a future issue. Note that the reinforcement does not need to be attached to existing stringers as the support is not structural in its intent.
Of course, a more standard AC 43-13B method would be to cut out the dent and make a patch. Chapter 4-58, Sec. f. refers to an acceptable method for making a flush patch. You cut out the damage and apply a patch to the rear side. Then you make a plug of the same sheet used in the first place, cut it to size, and fill the cutout hole. Either way, the builder should remember to pay attention to corrosion possibilities and apply some sort of protection to the back of the repair as well as the visible surface.
Feedback, as always, is appreciated, especially if you have ever tried this.