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What is PMAed, STDed, etc.?
In researching after-market instrument lights (see:
http://groups.google.com/groups?hl=e....tagonline.com ), I've run up against some terms that I think I should understand better. These are "STCed" and "PMAed". I understand that they're somehow related to having these lights (or whatever is under discussion) approved for installation, use, or some such in an aircraft. But I think I need to understand this better. STC stands for "Supplemental Type Certificate". This "certifies" a modification of an aircraft from its original design. PMA stands for "Parts Manufacturer Approval". This is an approval of a replacement part. I don't quite have the "big picture". For example, the Nulite web site indicates that all their products carry a PMA certification. Thus, again according to the site, "any certified person" can make the appropriate log book entry and the installation is "legal". That's right? Is "any certified person" an I&A? 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 not...when is an STC required instead of a PMA? Thanks... Andrew |
#2
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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. -- -Elliott Drucker |
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#4
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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 |
#5
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"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. |
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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. |
#7
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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 |
#8
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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 ----------------------------------------------- |
#9
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Bob Noel wrote:
are we confused yet? I'm not sure. - Andrew |
#10
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I was told in A&P school that It stands for Parts Manufactured Approved.
Tim A&P PP-SEL IA wrote in message ... 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. -- -Elliott Drucker |
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