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Heat Damage to J-3

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Joined
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Cameron Park, CA. (O61)
My neighbor had a fire in his hangar. The way I understand it is that there was a fire on the ceiling (that's all I know).

The ceiling is above his metal spar Piper J-3 cub. At the moment, I'm assuming the spar is 6061-T6. Are Cub spars ever any other Aluminum alloy?

In any case, 6061-T6 properties will change when sufficiently heated.... decreased yield strength / increased ductility. (not good for spars).

I don't know how hot the fire was or how hot the wing spar got, but the fabric on this airplane was not damaged at all.

What temperature does covering melt? I don't know the brand, but guessing it is a modern Dacron and not cotton or razorback.

What temperature does covering lose it's strength?

I'll assume the spars didn't get as hot as the covering. Fair assumption?

What advice should I offer him regarding the disposition of the material properties of his aircraft? I'm not asking if I should tell him if it's safe to fly...

What I am asking is, what would be the right steps for him to take to determine whether it is safe to fly?

Thanks!
Glenn
 

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