Mike Granby wrote:
I wonder if anyone can answer a few questions I have regarding PMAed
parts? Suppose I have a part I wish to install on a certified aircraft.
Are the following statements true or false?

PMA is authority to manufacture (or demonstration that part has been
legitimately manufactured if you wish).


1/ If the part is PMAed and the airplane is in the eligibility list,
and the PMA was obtained by virtue of the part being identical to the
original TC holder's design, the part can be installed by an A&P with
a logbook entry.

Correct, the TC is the authority to install the part. Since you are
putting things in conformance with the type certificate, it is not a
major modification. A 337 is hence not required, just the normal
log entires.

2/ If the part is PMAed by virtue of an STC which includes the airplane
in its approved model list, the part can be installed, but it must be
documented using a Form 337 which must be signed by an IA.

Correct, An STC is a major modification, you need to file a 337 with the
STC as the approved data.


3/ If the part is PMAed virtue of an STC which does NOT include the
airplane in its approved model list, it MIGHT be possible to get the
part installed, but it must be done via a form 337 and a field
approval.

Correct, in most cases. If the change is a major modification, you
need to file a 337 for a field approval. The STC is pretty good
approved data and the PMA shows the part is manufactured to reasonable
standards, but the FAA (or a delegate) must verify this.

If the change is not a major modification, then you can forgo the
337.


4/ If the part is not PMAed, it cannot be offered for sale for
installation of a certified aricraft per 21.303 unless it is TSOed, a
standard part etc. It might however be possible to get it installed
using a field approval.

....Really the same as #3. If it's a major modification and you
provide "data acceptable to the administrator" the field approval
is a possibility. If it's not a major modification, you can just
install the part.