Hidden Tinnerman Washers

A new approach to reinforcing holes for wheel pant attach screws.

Embedding Tinnerman washers in fiberglass provides a very clean look. The old method wasn’t working, so it was time to try something new.
After 1900 takeoffs and landings, mostly on grass strips, a flat tire on landing cracked the fiberglass on the left wheel pant

When new builders ask my advice on finishing their plane, I always recommend they paint their wheel pants one color, as eventually they will have to be repaired and repainted. Well, after 1000 hours and more than 1900 takeoffs and landings in my RV, mostly off and onto grass, my wheel pants were looking worse for wear and, unfortunately, it was time for me to take advantage of my own advice. The final straw was when a flat tire on landing cracked the fiberglass on the left wheel pant.

As the pants aged, the screw holes that hold them to the metal support bracket began to wear. I had started using Tinnerman washers long ago to keep the screws from pulling through. As the wheel pants chafed and moved around, it was obvious that their days would be numbered and I would have to address this wear item.

As the pants aged, Tinnerman washers were added to temporarily reinforce the holes for the attach screws, but they were also in need of repair.

In talking with my painter (I am not a painter unless the paint comes in a rattle can, and even then it is debatable), I told him that I wanted to embed Tinnerman washers in the fiberglass but leave the screwhead bearing surface clear so it would be washer on screw when the wheel pants are installed. Unfortunately, or fortunately, before I could get to the wheel pants, my painter friend showed up at my hangar, collected the wheel pants and disappeared into the sunset.

Two weeks later he had me pick up the wheel pants, and I’m happy to say the results were amazing. Prior to glassing in the washers, he scuffed the top and bottom so the fiberglass would adhere to the stainless steel Tinnerman washers. I’m sure some of you will say, “But the Tinnermans will break through the fiberglass.” You may be right but the original method didn’t work, so it was time to try something new. I’ll report back in a few months to let you know how they are holding up.

Post repair. The screw has been removed from the top hole and the buried Tinnerman washer is visible.
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Bill Repucci
Bill Repucci was handed his Private Pilot’s certificate back in the days when the written test was taken with a Number 2 pencil. At the time, Bill was told that he now had a “License to Learn.” And learn he did, mostly that there was humor buried in the quirky ways of those of us who call ourselves aviators.


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