What is PMAed, STDed, etc.?

In article ,
wrote:

A PMAed part or assembly is one that can be used as a direct replacement
for
the original part or assembly. Whether or not the owner/operator can
legally install a PMAed part depends upon the type of part and whether
its
replacement is within the bounds of allowed owner/operator maintenance as
defined in FAR 43.17(c). However, regardless of whether the PMAed part
is
installed by the owner/operator or an A&P, it requires just a simple
logbook
entry just like any other part replacement.

An STC introduces an alteration that was not covered by the airplane's
original type certificate. Installation of an STCed part or system must
be
accomplished in accordance with the STC. This may be a major or minor
alteration, but as I understand it, it would in any case need to be
signed
off by an A&P, and possibly an AI. In many cases a new weight and
balance
would need to be calculated and recorded.

and the OP wrote:
But I'd be using the Nulites not as a replacement for anything,
but as a new lighting solution. Does that make a difference?
That is, does this mean that a PMA is insufficient, and that an
STC is required?

If the part is not PMA'd for your aircraft, you'll need a different
"basis" for the approval of the installation in your aircraft. This
does not need to be via an STC.

As an example, a digital OAT probe I installed in my cherokee
was PMA'd for certain beechcraft aircraft but not my cherokee.
The installation this digital OAT probe was approved via a 337.

good luck.

--
Bob Noel

Bob Noel wrote:


If the part is not PMA'd for your aircraft, you'll need a different
"basis" for the approval of the installation in your aircraft. This
does not need to be via an STC.

Ah, so a PMA is aircraft-specific? That's a little suprising - although
reasonable in retrospect - as a number of aftermarket instrument lighting
vendors advertise that their product is "PMA certified", or some such. No
mention is made of "...for the following aircraft...".


As an example, a digital OAT probe I installed in my cherokee
was PMA'd for certain beechcraft aircraft but not my cherokee.
The installation this digital OAT probe was approved via a 337.

I'm confused about the role of a 337. When is one required?

One example is what you've cited: a change for which neither PMA nor STC
exists. But is one required for a replacement with a PMAed "part"? Is one
required for an STCed alteration?

- Andrew

"Andrew Gideon" wrote in message online.com...


Ah, so a PMA is aircraft-specific?

No. PMA ce

I'm confused about the role of a 337. When is one required?

A 337 is required to report any major alterations whether the are supported by
an STC or just "other acceptable data." Some people sometimes use "approved
by 337" to mean field approval.

One example is what you've cited: a change for which neither PMA nor STC
exists. But is one required for a replacement with a PMAed "part"? Is one
required for an STCed alteration?

There are two principles he

1. Approval of the modification, that is authority to make this change to the aircraft.
2. Approval of the part itself (It's manufacture, quality control, etc..).

The first is accomplished by either being supported by the Type Certificate, or an STC,
or other approved data, or being so minor as being inconsequential.

The second, can be accomplished by a PMA, a TSOA, the type certificate itself (for the original
manufacturer), by recognition of certain non-FAA standards (like MilSpec's for things like fasteners),
or by the owner himself producing the part in accordance with FAA-approved data.

Andrew Gideon wrote:

Ah, so a PMA is aircraft-specific?

Not exactly. If the item is (for example) a Cessna wing flap, then the answer
is yes. If it's a replacement for something more generic, it can be used to
replace that item on any aircraft that uses it. A good example would be one of
these lightweight starter motors. Since the part is legally a direct replacement
part, no STC is required.

The 337 is required for any change that the local FSDO believes is a "major"
modification.

An STC is legally a change to the original type certificate that allows you do
do something the original manufacturer didn't do.

George Patterson
A man who carries a cat by the tail learns something that can
be learned no other way.

In article ne.com,
Andrew Gideon wrote:

If the part is not PMA'd for your aircraft, you'll need a different
"basis" for the approval of the installation in your aircraft. This
does not need to be via an STC.

Ah, so a PMA is aircraft-specific? That's a little suprising - although
reasonable in retrospect - as a number of aftermarket instrument lighting
vendors advertise that their product is "PMA certified", or some such.
No
mention is made of "...for the following aircraft...".

I'm sorry. I was sloppy with my language. I shouldn't have
said "not PMA'd for your aircraft", but something more like
"not a PMA replacement for a part for your aircraft."


As an example, a digital OAT probe I installed in my cherokee
was PMA'd for certain beechcraft aircraft but not my cherokee.
The installation this digital OAT probe was approved via a 337.

I'm confused about the role of a 337. When is one required?

One example is what you've cited: a change for which neither PMA nor STC
exists. But is one required for a replacement with a PMAed "part"?

It is my understanding that replacing an existing part with
a PMA replacement part wouldn't require a 337.

Is one required for an STCed alteration?

Yes.

are we confused yet?

--
Bob Noel

Bob Noel wrote in
:

Is one {PMA} required for an STCed alteration?

Yes.

Not quite.

A part may be manufactured by the owner/operator and installed under
STC, or it may be manufactured *and installed* by the holder of the STC
without PMA. Both these minor points are seldom worthy of note, but
they are there.

For example: GAMI designed their new fuel injectors. They went through
testing and the STC was awarded. They were then allowed to make them
and install them on all aircraft/engines for which the STC applied.

The FAA would not allow the PMA application to be even be submitted
until the STC was approved. [It's not clear that this is a rule, so
much as an FSDO made up rule.] Until the PMA was approved GAMI could
not sell the injectors to anyone else for installation elsewhere. You
wanted the injectors, you flew to Oklahoma and had GAMI put them in.

Once the PMA was approved the restriction went away.

-----------------------------------------------
James M. Knox
TriSoft ph 512-385-0316
1109-A Shady Lane fax 512-366-4331
Austin, Tx 78721
-----------------------------------------------

Bob Noel wrote:

are we confused yet?

I'm not sure.

- Andrew