Caulking Wing to Fuselage Joint

Submitted by Neal Garvin, Glasair SIIS-RG N15F

Here is something to think about when you are getting hammered in severe turbulence.


When you permanently (or for the last time anyway) attach the wing to the fuselage, you put a good solid bead of caulking between the wing and the wide, built up fuselage flange (with the heavy longeron above it). That bead of caulk, if wide enough, dense enough and if it fills all the gap, will transfer almost 100% of the positive G loads to the fuselage sides along the entire length with the wing attach brackets and bolts seeing very little loading.

It’s the negative G maneuvers that will stress the wing attach fittings and bolts. But, if you don’t use any caulk, or it is soft and mushy, the wing attach fittings and bolts will always be under a load. And your seat pans and wing will fill with water every time it rains.

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Omar Filipovic
Omar Filipovic is president of the Glasair Aircraft Owners Association as well as the chief tinkerer and content editor for this website. He is also the web editor for Kitplanes Magazine. Omar is building a GlaStar in Portland, Oregon.