What is PMAed, STDed, etc.?

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...

It sounds from the above like an STC is required before any major alteration
because it "provides authority to make the major alteration". Is that
right?

An STC is one way of getting approval for the alteration. Other "data
acceptable to the administrator" is allowed as well. This is called a
field approval (or sometimes incorrectly, a one time STC).

A lot seems to hinge on the distinction between "major" and "minor"
alterations. What is the difference? Given a particular change (ie.
replacing a panel overlay, or adding instrument lights), how does one know
into which category the change falls?

The definitions are here (I'm not going to post them inline as they are a bit long):
http://www.access.gpo.gov/nara/cfr/c...4cfr43_00.html

Some of it is a gray area. Somethings people read more into it than others.
For example, just because something changes the w&b, it is not a major
alteration. It is only a major alteration if it changes the permissable envelope.

"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.

I did a Google search for "owner produced parts" then started clicking.

Very interesting reading!!

1. http://www2.faa.gov/avr/afs/news/arc...2002/Parts.htm

2. http://www.dvcfi.com/aviation/stc.php

3. http://makeashorterlink.com/?L2A512696

4. http://makeashorterlink.com/?H1C521696

Talked to a guy at my airport who is doing much of this with his 177
project. He said he's surprised more owners don't make parts for their
planes, or have the parts made for them. Measure it, build it - is his
motto.

--
Montblack

("Dan Thomas" wrote)
Aircraft manufacturers publish parts manuals for the airplanes they
build. The law says that you must use the parts specified in the
manual when replacing things. If the part has an industry-standard
number, like an AN bolt or fitting or wheel bearing, you can buy it
from any aircraft parts supplier.
If the number is a proprietary number (invented by and belonging to
the airplane manufacturer), such as a throttle control cable, the
requirement to use only that part means that you have to buy it from
the airplane dealer. The manufacturers are inclined to take advantage
of this and we see some ridiculous prices.
snip

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.

On Wed, 19 Nov 2003 14:01:52 -0600, "Montblack"
wrote:

I did a Google search for "owner produced parts" then started clicking.

Very interesting reading!!

1. http://www2.faa.gov/avr/afs/news/arc...2002/Parts.htm

2. http://www.dvcfi.com/aviation/stc.php

3. http://makeashorterlink.com/?L2A512696

4. http://makeashorterlink.com/?H1C521696

Talked to a guy at my airport who is doing much of this with his 177
project. He said he's surprised more owners don't make parts for their
planes, or have the parts made for them. Measure it, build it - is his
motto.

I'd be interested in knowing if this guy is generating approved data
for these parts. If he isn't, he is doing no more than producing
numerous unapproved parts with which to get himself and his mechanic
and/or inspector violated. ... not a clever money-saving scheme.

And your background and authority for making this statement are?


Jim



Gene Kearns
shared these priceless pearls of wisdom:


-Talked to a guy at my airport who is doing much of this with his 177
-project. He said he's surprised more owners don't make parts for their
-planes, or have the parts made for them. Measure it, build it - is his
-motto.
-
-I'd be interested in knowing if this guy is generating approved data
-for these parts. If he isn't, he is doing no more than producing
-numerous unapproved parts with which to get himself and his mechanic
-and/or inspector violated. ... not a clever money-saving scheme.


Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com

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

On Wed, 19 Nov 2003 16:21:09 -0800, Jim Weir wrote:


And your background and authority for making this statement are?




Are you the credentials police?



If you take issue with the substance of what I have said, offer
information contrary to my assertion. FAR 21.303 does not give blanket
authority to an owner to produce any sort of part using any sort of
materials and any sort of means available. (Nor does it give a
mechanic permission to install an unapproved part.) If you do disagree
with my assertion, I suggest you read FAR 43.13 and FAA Order 8300.10
Chapter 83 for content and then offer some means available to the
owner/operator for legal approval of owner/operator produced parts
other than:

(1) reverse engineering and field approval or
(2) securing original manufacturing data from the TCD or PMA holder
or
(3) securing original manufacturers data via freedom of information
act from the FAA Aircraft Certification Directorate

In any event, the part must be certified as airworthy in the
maintenance records by the owner/operator and that assertion should
not be made unless the part conforms to the original type design. A
mechanic that installs owner/operator parts not so (accurately)
certified in just asking for trouble.






Gene Kearns
shared these priceless pearls of wisdom:


-Talked to a guy at my airport who is doing much of this with his 177
-project. He said he's surprised more owners don't make parts for their
-planes, or have the parts made for them. Measure it, build it - is his
-motto.
-
-I'd be interested in knowing if this guy is generating approved data
-for these parts. If he isn't, he is doing no more than producing
-numerous unapproved parts with which to get himself and his mechanic
-and/or inspector violated. ... not a clever money-saving scheme.


Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com

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
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