(John Galban) wrote
"It depends on the original horse power. If you had a 135 hp the
spring stays in place. If you had an original 135 hp, converted it to
150 hp, the spring stays. If you had an original 150 or 160hp and
converted it, you remove the spring. That's just the way the STC was
written.
Also if you go to 180 hp add a constant speed the spring stays or is
added."

Just to add confusion, I know of at least one 135 that was converted
to 150 where the springs were removed. Legal? Who knows. Some
people are removing springs based on the piper drawing, with no STC at
all.

The key here is getting the Form 337 thorugh the FSDO. Usually
something that says "Removed p/n 123-456 (interconnect spring) IAW
Piper drawing p/n 789-012" will sail right through, because the guy
really doesn't want to hassle with looking up those drawings, and it
all sounds good. Once the Form 337 goes through, it takes a real
asshole of an IA to object to the modification come annual time, and
the solution is simply to use a different IA.

Michael