To PMA or not to PMA

By Mike Broderick — September 30, 2013

So what is a PMA part anyway? What is a bogus part? How did PMA become an industry? Why have PMA parts enjoyed popularity? Are they safe? Are PMA parts acceptable outside the US? Ahhh, sit tight my faithful students; all these questions will be answered as well as why the original equipment manufacturer (OEM) really, really, doesn’t like PMA. So get ready to navigate with me through the informational waters of PMA, soaking up facts about the PMA industry while also expanding our mixed bag of usable and useful cocktail knowledge (CK) along the way.

Now, of course, the first term we need to define is PMA. PMA is an acronym for “Parts Manufacturing Authority”. A PMA part is an approved replacement for the OEM original. OK?  As we proceed through the lesson, I will refer to a plethora (like that word? Go ahead look it up.) of Federal Aviation Regulations (FARs). But don’t fret; I have purposely avoided publishing the written regulation itself, as we really don’t have the time, space, or stamina to digest the amount of legalese that make up these policies.

However, if you have a burning desire to read them you can find each one in its entirety on the FAA web site:

Bogus (unapproved) Parts

Now that we know what the letters PMA mean, we need to define what a PMA part is. But, whad’ya say we kick start the conversation with what PMA IS NOT and talk about “unapproved parts” aka “bogus parts” first. And where better to start than with the example of the repair depicted in the above photo on this page. Now, this is a perfect example of using a bogus part as a replacement for the actual factory approved fuel system air inlet duct. Even though you will have to give the guy credit for being creative, this obviously does qualify as an illegal repair using a bogus part.

So just how do we define a bogus part? The term “bogus parts” is an expression which, loosely defined, has come to describe several parts categories, ranging from properly manufactured parts lacking required documentation, known as unapproved parts, to defective and deliberately counterfeited parts.
Unapproved Parts are defined as follows: Under FAA regulations, all aircraft parts manufactured without FAA Approval (specifically, FARs part 21.305 or repaired under the terms of PART 43), are unapproved parts. This catchall classification includes counterfeit parts, stolen parts, production overruns sold without authorization, life-limited parts in exceedance of their time limits, approved parts improperly returned to service, and fraudulently marked parts, or parts which have no traceability.

Counterfeit Parts are defined as those made of inferior properties or materials and distributed with the intent of replacing an “approved part”.

Some folks would have you think that PMA and bogus are interchangeable terms. And to quote one of my surfing buddies about this association of terminology, “that’s totally bogus, dude.” And in a little bit you will see that this assertion about PMA is refuted through an extensive investigation by the FAA. Also, as you might imagine, the biggest group of PMA detractors are the OEMs. We will discuss the contentious relationship between the PMA providers and the OEM a little later.

However, suffice it to say the one and only subject upon which both the PMA providers and the OEMs can agree is what do we do about people/companies who sell and or use unapproved and or counterfeit parts. And both concur that these purveyors of bogus parts need to be caught and punished. Well, until 2000 there was no single systematic federal law that targeted this problem. In 2000, the Aircraft Safety Act encapsulated eight violations of the US Criminal code and set up a four-tier sentencing approach to punish violators. The punishment ranges from a 10-year imprisonment and fine up to $250,000 to life imprisonment and $1 million for an individual and $20 million for a corporation. The penalty is dependent upon the affect the unapproved part/parts have on the safety of flight and if failure of the part or parts results in no incident or injury all the way to death. The US government is not fooling around with purveyors of bogus parts, which is fine by me. Anyone who places profit over people’s lives deserves punishment to the fullest extent of the law. At the time of this writing the Federal Bureau of Investigation (FBI) has carried out over 142 indictments, and 98 convictions, netting over $50 million in criminal fines, restitutions, and recoveries in the cases involving unapproved aircraft parts. Additional investigations are ongoing as we speak.

Approved Parts

An “Approved Part” is defined as a part which conforms to FAA approved production standards FAR 21.305, or repaired under the terms of Part 43. (Hint: These would be type certificated (TC’d) and PMA’d parts.) Well, are there parts that can be legally used in a certificated aircraft that are not PMA’d or TC ‘d under a TSO? Yup, there are such parts that are neither PMA or produced under an FAA approved TSO. The following are examples of parts that are considered exceptions to the PMA rules for producing modifications and or replacements for TC’d parts.

1.  An aircraft owner or operator may produce parts for installation on their own aircraft, or aircraft appliance, without a PMA. The installation of those parts must comply with 14 Code of Federal Regulations (CFR) Part 43. However, the owner may NOT sell these parts for general consumption on other certificated aircraft.

2.  An Air Carrier operating under 14CFR Part 121 or part 135 may produce parts for installation on its own product without a PMA, provided the installation of those parts is approved in accordance with 14CFR part 43 and complies with the air carrier’s accepted maintenance procedures manual and instructions. Again, the air carrier may NOT sell these parts for general consumption on other aircraft not owned by this air carrier.

3.  Finally, a part produced by an FAA-certificated repair station with the intent of installing it on a type certificated product or aircraft that the repair station has in house for repair. Such parts may NOT be offered for sale as separate items. However, before you venture into this activity, make sure to study the FAA Advisory Circular 43-18, Fabrication of Aircraft Parts by Maintenance Personnel of March 2006, for details and direction.
I am sure you noted that the recurring similarity of between these parts is that they cannot be reproduced for public consumption.

PMA Parts

Now that we know what a PMA part is not, let’s talk about what a PMA part is. A PMA part is an approved part that is produced under a Federal Aviation Administration (FAA) design and production approval as defined earlier. Approved parts are established under a PMA, or Technical Standard Order (TSO), in conjunction with type certification procedures through FAA approval, or by conforming to recognized industry specifications.

As a side note, some approved parts have, in certain applications, a “life limit” placed upon them during the approval process. An example of these parts would be helicopter blades, some internal rotor head parts, turbine engine compressor wheels, blades and/or discs, and hot section wheels, blades and/or discs. The life limits can be in the form of a calendar time, operational/flight hours and or an engine RPM limit range and start events, also known as cycles. With respect to engine rotating parts, most have operational hours and cycles as limits, and must be removed from service, depending on which limit is reached first. These particular parts (and there are many more not named here) operate in what is considered a high stress environment and thus can fatigue and fail before that particular part might exhibit observable wear or weakness. As you might imagine, the FAA approval process for these life-limited parts is arduous and expensive for the manufacturer.

In order for a PMA to be issued to a particular part the following two conditions must be satisfied:

1.  The FAA has reviewed the design of the part to assure that it is safe and meets the requirements of the FAA regulations, or as the saying goes, “equal to or better than the original.” The design approval certifies that a replacement part or part modification complies with the airworthiness standards of eligible products, (aircraft, engine or propeller) and that the part or modification doesn’t infringe upon the OEM’S patent. And here is the laundry list of FAA regulations, Advisory Circulars and FAA Orders used in this process.

l    Part 21, Certification Procedures for Products and Parts
l    Part 21, Subpart K, Approval of Materials, Parts, Processes, and Appliances (Sections 21.301, 21.303, and 21.305)
l    Part 21, Approval of material, Parts, and Appliances, section 21.502
l    Part 43, Maintenance, Preventive Maintenance, Rebuilding, and Alteration
l    Part 45, Subpart B, Identification of Aircraft and Related
l    Products (sections 45.11 through 45.16)

l    AC 43-18, Fabrication Manufacturer Approval Procedures

l    8110.42, Parts Manufacturer Approval Procedures

2.  Next, the FAA must have reviewed the production quality system to make sure that there is a system in existence and established to verify that each part which is manufactured meets the FAA-approved design.

So, as a PMA manufacturer what do I have to do to prove to the FAA that my part design and part is equal to or better than the original? Well, the hopeful PMA manufacturer shows this compliance by using a couple of techniques: a comparative analysis showing that the part in question is the same in form, fit and function as the original approved part, or qualitative analysis showing that through functional test and computation the PMA part meets the specifications of form, fit, and function. A PMA manufacturer may also rely on a licensing agreement with another approved manufacturer who has already obtained approval of the design in question, and thus can receive approval by demonstrating identicality. Identicality means, of course, that the part design, manufacturing process and the subsequent part is identical to that of the type certificated part. Some OEMs will license a supplier to produce a part that follows this process.

OK, if the PMA and the OEM part look the same, how do I know which part I am buying? Because there is no, or should be no, visual or dimensional difference between a part produced under a TSO from one produced under a PMA, a unique part number is assigned and permanently affixed to the PMA part. This distinctive identification system is mandated in FAR 45.15 and is in place so as to avoid any confusion between these two approved parts.

The History of PMA

PMA came about in July 1955 when the FAA, in an effort to help civilian owners keep out of production surplus military aircraft operational, considered it acceptable for companies that weren’t OEMs to design and make spare aircraft parts. This created the PMA industry and produced two types of PMA suppliers: licensed suppliers (who work with the OEM), and those who would eventually compete with the OEMs (competitive suppliers). Licensed suppliers produce parts in collaboration with OEMs, not only removing the financial burden of providing support for these out of production aircraft, but also to help the OEM meet demand and reduce the cost of production of current inventory. Well, it wasn’t long before the entrepreneurial spirit grabbed a few licensed PMA manufacturers as well as attracting other manufacturers to this innovative element of the aviation industry. They recognized a financial opportunity and began to challenge the OEM for market share on current production aircraft parts. Thus evolved the competitive supplier who, while providing acceptable alternative parts to the operator, also provides financial grief to the OEM. And it is this competition for market share that has strained the relationship between the OEM and the manufacturer of the PMA part.

So why have PMA parts become a popular alternative? As a rule, they are less expensive than the OEM original parts and they are generally more available. Less expensive, and readily available? Ah yes, this is true. How can they do it? Well, the PMA manufacturer only has to invest in the engineering and manufacturing costs to produce spare parts. And the PMA manufacturer will “cherry-pick” the parts, reproducing the ones that have the most replacement activity. The hapless OEM, on the other hand, has to fund the entire component, including engineering, research, etc. as well as an inventory of spare parts for the aftermarket support of said component. For example, an engine manufacturer has to pay for the engine development, production of the engine, and spare parts to support the engine in the field. Put these costs together, plus the financial burden of continuing airworthiness documents (overhaul, parts, and field maintenance manuals and bulletins) support personnel, inventory costs etc. As you can see, the list is long and costly.

I want you to notice that I did not use the term “cheaper” as an economic portrayal of a PMA part as I don’t want any misconception about the quality of a PMA part. Contrary to what the OEMs say, a PMA part is of the same quality as the original, and sometimes better. Better? Why? Well, the PMA provider has the advantage of evaluating the OEM part, discovering and improving upon any weakness discovered during the evaluation process. Until recently, the OEMs continued to bash the PMA part with statements about warranty violations and safety concerns. In 2008, after an extensive FAA and EASA investigation which was requested by the OEMs, these regulatory agencies could find no statistical evidence that PMA parts are a safety concern, nor could they find any fault with their approval process of PMA parts. The FAA issued a Special Airworthiness Information Bulletin (SAIB) #NE-08-40 publishing these facts and extolling the quality of the PMA part. This SAIB really caused the OEMs to howl like frightened cats, although they have no one but themselves to blame. It is perfectly logical that they are opposed to PMAs, but as we have learned, their opposition has nothing to do with safety.

You see, enlisting the FAA’s aid in this matter worked against them, as it caused the FAA and EASA to really research the safety record of PMA parts. What they found was that OEM’s information in their maintenance manuals and service bulletins was anti-PMA. For instance, when an OEM issues formal instructions in their maintenance manual or service bulletin that you are not allowed to put PMA parts in the engine, that puts the installing technician between the proverbial rock and a hard place. Per Advisory Circular (AC) 43-13-1A, you are supposed to follow the OEM’s instructions. However, AC43-13-1B says that you can use anything that will safely return something to its original condition.

Well, as I stated earlier, the result of the FAA scrutiny was that the FAA has had good oversight over PMA approvals, that PMA parts are safe, and that the OEM concerns are apparently driven by economics rather than by safety concerns. Careful what you wish for.

One thing resulting from this that does favor the OEM is that the PMA manufacturer can no longer tell the overhauling/maintenance community to use the OEM documents as the criterion for continued airworthiness, which, if you think about it, makes sense. The PMA part should be inspected to its own set of maintenance and overhaul standards. This added responsibility now causes the PMA folks to monitor the repair of their parts in the same manner as the OEM.

During the last 12 years, requests for PMA approvals to the FAA have soared. While the ramp-up for new aircraft production has increased lead times on OEM spare parts, an estimated 550,000 PMA parts have been brought to the marketplace. There are industry estimates that the FAA is approving about 1,500 applications a month from over 2,600 companies. OEM apathy to the operators’ complaints about increasing prices, coupled with poor parts support and topped off with the support of the FAA, has fueled this increase in PMA parts usage. PMA has enjoyed such growth that one of the biggest opponents to the PMA, Pratt & Whitney, has decided, “if you can’t beat ‘em join ‘em.” P&W have placed one manufacturing foot in the PMA bucket via an ongoing program to produce and market PMA parts for the General Electric CFM 56-3 engine. And with over 12,000 CFM 56 variants in service, this is a heck of a good market in which to jump. P&W made the decision not to develop an engine in competition to the CFM 56 series, but rather redirected its resources from developing an engine to developing PMA parts for the competitor’s engine. Pretty good use of capital and manpower, I would say.

As with all PMA manufactures, P&W has targeted the parts most often replaced during maintenance and overhaul. They have studied the reasons the parts need replacement, as well as the rate at which they are replaced. Then armed with these statistics, they can devise structural improvements for the parts they are manufacturing under PMA. This research also is used to improve their own parts, which helps defend against a PMA assault on their product.

Customer Base for PMA
Well, with the FAA firmly behind them, more favorable pricing, and plenty of parts on the shelf, the customer base for PMA is growing. So who is the customer base? The airlines, the cargo carriers, the military, the commercial/business operators, and the general aviation communities, that’s who. Let’s look at each of these groups to see how they are reacting to PMA.

The Airlines

As you know, the airline business is one of the most competitive in the world. Profit margins are thinner than the hair on a frog’s chin. Maintenance costs are under a constant spotlight from the accounting department, so if PMA parts can save them money you can bet they will look at the possibility of using them. The most common use is, of course, in the maintenance/overhaul of the engines. What does concern the maintenance department, though, is the OEM hitting them with the billion dollar question: “Are you willing to risk lives, law suits, and ruining your good name because you decided to use cheap parts?” So, to remove any doubt about who might be right, the PMA manufacturer who says their parts are safe and inexpensive or the OEM who claims that PMA parts are unsafe because they are inexpensive, the airlines will commission a side-by-side comparison in a controlled evaluation. In many cases, the quality between parts is comparable, so it becomes a simple application of economics. If you are an airline and are saving 30 percent on a PMA part (which is about the industry average) versus an OEM part, and are spending about $5 million in PMA parts, you have just saved the company over $1.5 million a year. Kind of an economic no-brainer, huh? So the fact that the airline folks also use PMA as a bargaining stick to beat the OEM with should not be a surprise. If the OEM wants to keep PMA out of the airline’s maintenance department, they will make a concerted effort to control costs for their support parts as well as improve availability because the other factor that will cause an OEM to turn to PMA is availability. An aircraft on the ground (AOG) costs money and is the other side of the economic coin.

Cargo Carriers

The freight haulers have slightly different issues from airlines when it comes to PMA parts. First, the cargo operators have much smaller fleets, which prevents them from enjoying certain economy of scale benefits that the large fleet airlines have available to them. Second, they tend to have healthier profit margins than those of the airlines. Together, on the surface, these factors make the financial consideration of PMA parts not quite as pressing as their people moving compatriots. However, the real motivator with this group is parts availability. As with the airlines, an AOG costs money, making availability of the part the key issue with these guys as well. So although they are happy about the cost savings of PMA, they are really motivated by the fact that PMA is more accessible.

The Military

If there is one group with a real vested interest in saving money it is the US Department of Defense. Some would credit the air force for making the PMA industry as successful as it is. Remember the infamous $6,000 hammers and the $2,000 toilet seats? I do, and I remember the taxpayer outrage and demand for improved military accountability with regard to spending. Well, thanks to that fiasco, the air force is a world leader in the use of PMA parts, but truth be known, all the US military rely heavily on PMA parts. And considering that 29 percent of everything flying over the US belongs to the Department of Defense, this is not only a good customer base, it is another endorsement for PMA.

The Commercial/Business Operators

Safety, aircraft availability, cost; it seems like we have discussed these three factors before. Well, it is no different with this customer base. The aircraft flying in fractional ownership programs are faced with keeping a safe aircraft available without breaking the bank. And as for expensive business jets that are wholly owned and operated by one company, holding the cost of their upkeep to a minimum while simultaneously maximizing availability is extremely important as well. With both types of operations, the OEMs assert that even though using their parts may be more expensive, the OEM part is more reliable, and in the end, will fetch a better price for the aircraft. However, the bean-counters contend that an FAA-approved part that is available today for a lower price trumps the OEM’s allegations. Of course the chief pilot, who is interested in safety and keeping the flight department from going away (in that order of course), is for anything that satisfies both priorities.

The General Aviation Community

Whether it is the flight school, the operator trying to make a buck with a government contract or the weekend enthusiast, PMA parts are the answer. As with the other members of the aviation world, safety followed very closely by cost, are the driving factors for which a part is purchased and installed.

PMA Approval Outside the US

With PMA acceptance growing globally, using the existing structure for type certificate confirmation becomes very important to the progress of opening up new markets for PMAs. Even though validation has historically been focused on validating type design for complete products, the same principles apply when a PMA design needs to be validated in an importing nation. The PMA design might need to be validated in the event that the importing nation does not have a bilateral agreement with the nation whose regulatory agency issued the PMA. A PMA design may also need to be validated where the special nature of the PMA part requires it, such as the acceptance of a PMA part in Europe if the PMA is for a critical part.

The issue of international validation has been the subject of discussion between the EASA, FAA, and TCA, during a meeting at the 2009 Europe/US/International Aviation Safety Conference. Although the focus of discussion was on type design validation, without specifically spotlighting PMA, the principles of the process are the same. Without getting into the specifics from each of the representatives, the consensus was that validation should be approached with an open mind on acceptance of the technical data from the regulatory agency that issued the PMA. The metric to acceptance should not be efficiency as much as it should be effectiveness. Each validation should proceed more smoothly than the previous event as lessons should have been learned and the application of these applied to the next occurrence.


The fact is, PMA has become a globally accepted alternative. As competition heats up for the operator, the distance between the cost of doing business and the profit from that business is shrinking — also a fact. The one cost that owner/operators have found they can control, somewhat anyway, is the cost of the parts for maintenance through the use of PMA. The stigma of PMA = UNSAFE has been challenged and refuted, and not by anecdotal journalism but through hours and hours of safe operation, much to the annoyance of the OEM.

The OEM is also in a tough economic situation. Competition between OEMS for market share is intensifying and they too are watching the erosion of their profit margin. They need the revenue of aftermarket parts sales to help support research and development as well as the cost of producing and bringing to the marketplace a type certificated component. As we learned, Pratt & Whitney has taken a look at PMA as another unique opportunity to remain profitable. One other positive note for the aircraft owner is that the advent of PMA has caused the OEM to look hard at improving their parts and reducing their production costs. So either way, whether PMA parts or OEM parts, the winner from both a safety and economic standpoint is the customer. Now, economics tells us that the less expensive parts will replace their more expensive counterparts.

However, just as there are those who go to the local NAPA parts store to buy parts for their cars, there are also a good number of people who won’t use anything but genuine Ford, Chevy, or Dodge parts in their cars. It is the same for a certain population of aircraft owners, operators and airlines — nothing but OEM parts for their aircraft.

This is an interesting scenario for technicians to watch, that’s for sure. Because if you think about it when it comes to maintenance, our job is twofold:
First, make sure that whatever part we use is safe for use in the aircraft we are working on.
Second, that our maintenance allows the pilot to do his job safely and effectively.
And so until next time, class is dismissed.

About The Author

Mike Broderick

Mike Broderick is V.P. of Business Development at Helicopter Engine Repair Overhaul Services (HEROS). Over the past 35 years, he has served as a shop technician, engine shop supervisor, Engine Program Director, Director of Maintenance, Director of Operations, and owner of a Rolls-Royce engine overhaul and MD Helicopter component overhaul shop. He is a certified A&P, and holds a Bachelor of Science degree in Aviation Administration. As well, Mike has been appointed as an FAA representative for the FAA Safety Team (FAAST) and is a member of the HAI Tech Committee. Mike is a regular contributor to Air Maintenance Update.

View all articles by Mike Broderick.