PMA Questions

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?

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.

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.

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.

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.

Thanks in advance for any light you can shed on this...

Yes, on all four items.

Bill A&P IA


On 5 Dec 2005 18:38:57 -0800, "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?

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.

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.

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.

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.

Thanks in advance for any light you can shed on this...

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.

Bill and Ron gave you good information. Think of the PMA as simply a
statement that the part is an approved substitute for the part from the
OEM that is being replaced.

One minor issue - a company can make a part and get an STC without
getting the PMA. It can then be installed *by the manufacturer* but it
can not be "offered for sale for installation on a certificated
aircraft" by someone else. For example, when GAMI was working on their
injectors, the FAA would not accept a PMA application until the STC had
been issued. So for a time they had the STC but not the PMA. They
could make the injectors and sell them to you, but THEY had to install
them. Once they got the PMA as well, then they could just mail them to
your local A&P for installation.

jmk

Thanks to everyone for their replies. The reason I brought this up is
that I am engaged in a discussion with someone on a Pipers discussion
group, and he is asserting that a PMAed part can be installed without
further approval or paperwork, whether or not the PMA was obtained as a
result of identicality, or as a result of an STC. My understanding that
was that STCed parts needed a 337 and an IA, and that the PMA had
nothing to do with it, other than meeting the requirements of 21.303
for offering parts for sale.

"Mike Granby" wrote in message oups.com...

Thanks to everyone for their replies. The reason I brought this up is
that I am engaged in a discussion with someone on a Pipers discussion
group, and he is asserting that a PMAed part can be installed without
further approval or paperwork, whether or not the PMA was obtained as a
result of identicality, or as a result of an STC. My understanding that
was that STCed parts needed a 337 and an IA, and that the PMA had
nothing to do with it, other than meeting the requirements of 21.303
for offering parts for sale.


Yes, the STC requires the 337 for installation on the airframe in question, but the maintenance of that STC can be done
just like any other maintenance; install OEM, PMA or owner produced parts signed off by an A&P.

Don't you need an IA to sign the "Return to Service" box of the 337?

Mike Granby wrote:
My understanding that
was that STCed parts needed a 337 and an IA,

Yes, always.

Newps wrote:


Mike Granby wrote:
My understanding that

was that STCed parts needed a 337 and an IA,


Yes, always.

Unless the 337 is signed by a manufacturer or repair station....

Indeed. But is there such a thing as an STC for a minor modification?
Is there any situation in which a vendor might choose to use an STC to
get a part on to his PMA, but where the existance of the STC does not
per se render the change major and thus in need of a 337?