TSO'd, non-TSO"d. ......................

[CptKelly]

TSO'd. non-TSO'd instruments and radios. Is one any better than the other? Can either be used in a certified aircraft? How about used in EXP?

Mike in NC

[bob turner]

I just attended an IA conference, taught by Bill O'Brien, of the FAA. It was a startlingly good seminar on all things a mechanic should know. Bill said that PMA parts need only a logbook entry; TSO parts require a 337. I have to admit that I really do not understand why, but when I told him my TSO radio was a slide-in replacement for my old non-TSO, he said I was illegal without the 337.
So there are some interesting questions here:
First, do we only need the 337 for the first installation (like the seatbelts in our old aircraft that pre-date the TSO requirements) or do we need to do a 337 each time a seatbelt or tire is replaced?
Second, if it doesn't have a PMA or a TSO, and didn't come from Piper, can it be installed at all (absent, of course, an STC)?
Bill is a Cub owner, and is extremely knowledgeable and engaging, but so far I have not queried him in depth on these issues. He is working on a project to convert older field approvals into "approved data" so that we can do reasonable stuff to light aircraft, but has not received much input from 337 holders. Maybe we should change that; I'll start a thread soon.