It doesn't matter if the POH talks about it, what does the equipment
list say?



Robert M. Gary wrote:
They would probably need a 337 to remove the seat since the plane was
not certified without a seat (just like only some planes can fly w/o
the doors). However, some planes are certified to fly w/o the back
seat. My Mooney POH specifically talks about flying with the rear seat
out. I'm not sure about the Piper.

-Robert