http://www.faa.gov/library/manuals/e...a/2_001_00.pdf

Has a decision making flow chart as well as other determination procedures
that the inspectors follow to determine if you need a 337.

Jim

"Robert M. Gary" wrote in message
ups.com...
http://www.planeplastics.com is telling me I need to get a 337 to
replace my plastic air vent covers. Is that true? What would an
inspector be looking for? Too much cooling for the backseat and too hot
up front?

-Robert