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The doubler is not a patch there in no damage under it.
It is just a term
My View It is a Patch
Originally Posted by Piper J3
Not a patch. Patches are for bicycle tires. Aircraft don't do "patches". Correct term is doubler. Look at the bottom of your fuselage and you will see a number of doubler plates in high stress locations. Doublers are used to distribute load safely into the surrounding skin...