hotrod180
FRIEND
Port Townsend, WA
....§ 4a.597 Propellers. Propellers shall be of a type and design which has been certificated as airworthy in accordance with the requirements of Part 14 of this subchapter or shall have been approved as airworthy in accordance with previous regulations, except that wood propellers of a conventional type for use in light airplanes need not be certificated. ....
In this case, it seems to me that "of a conventional type" are the key words.
I wouldn't classify a Catto prop as a conventional wood prop-- would you?