In addition, what happens if I buy a VFR plane and then replace the
engine and avionics and make it a IFR platform? Am I the builder for
the parts I put on it or does the fact that I bought an already
airworthy plane make it in essence little different than buying a 172?


Bryan Martin
N61BM, CH 601 XL, Ram Subaru, Stratus redrive.

There is only one builder and that is established when the
Airworthiness
Certificate gets issued. Modifications afterwards may require the FAA
to issue additional operational limitations depending on the nature of
the modifications. An example would be a VFR limitation that you want
changed to allow for IFR operations. Installing a different engine
will generate a subsequent flight test period similar to the hours
that had to be flown off initially. Minor mods do not need anyone to
sign off on as there is no "return to service" signature needed as in
normal category aircraft. This is a primary advantage of the Amateur
Built Experimental--no STCs, no 337s, no return to service--much
different than the rules pertaining to a 172,