Paul:

A couple of years back I was on a cross country and I found a large nick/gouge on the "back side" of one of my rear engine prop blade and a 2" dia. hole on the inside of my right boom about 3 feet back from the prop.

Turns out the thru bolt for the muffler rear support broke and the nut with a section of bolt fell out thru one of the exhaust pipe holes and hit the prop. It took a long time to find the broken bolt.

Bottom line is you need to do a thorough inspection of you engine compartment because more than likely the item causing the damage came out of there.

Regards,

Ray Torres