features PMA takes its place

Once shunned, PMA parts have become an integral part of the helicopter product support landscape.
Avatar for Elan Head By Elan Head | May 20, 2022

Estimated reading time 12 minutes, 2 seconds.

Based in El Dorado Hills, California, Aerometals has been in business for nearly 40 years. The aerospace company is a supplier to commercial original equipment manufacturers (OEMs) as well as the U.S. military, but a certain segment of the industry knows it best as a maker of PMA parts for MD 500 helicopters.

A close-up look at Van Horn Aviation’s composite main rotor blades for the Bell 206L LongRanger. VHA Photo

Short for “parts manufacturer approval,” PMA refers to the process by which the U.S. Federal Aviation Administration (FAA) approves an applicant other than the OEM to make replacement parts for a type certificated product. Over its four decades of operation, Aerometals has both observed and contributed to a major shift in how PMA parts are perceived.

“When we first started in that market, the industry was not very accepting. [PMA parts] were seen as subpar, not good quality,” recalled Lorie Symon, Aerometals president and CEO.

But especially in recent years, she said, that perception has changed: “Basically the market is starting to be accepting of PMA parts, starting to understand that PMA manufacturers are held to the same quality standards that the OEMs are.”

Over the years, Aerometals has developed a strong reputation for its PMA parts for the MD 500 series. Lloyd Horgan Photo

That means more helicopter operators are now taking advantage of the benefits that PMA parts can provide, including cost savings, better availability and, in some cases, improvements on the original design.

Earning respect

To be sure, the sector’s dismal reputation in those early years was not wholly undeserved. In the 1990s, a proliferation of unapproved parts for aircraft led to the FAA announcing an “enhanced enforcement policy” to crack down on parts makers that were shortcutting the PMA process. OEMs pursued lawsuits and damning public relations campaigns against even approved PMA holders, fostering widespread mistrust of their products.

In 2006, Pratt & Whitney shook things up when it announced plans to manufacture PMA parts for turbofan engines made by competitor CFM International, a joint venture between Snecma (now Safran Aircraft Engines) and General Electric.

The entry by a major OEM into the PMA market was pointed to as evidence of the legitimacy of the PMA process.

PMA parts can offer cost-savings, better availability, and, in some cases, improvements on the original design. Aerometals Photo

The FAA reinforced that position in 2008 when it issued a special airworthiness information bulletin defending holders of PMAs and supplemental type certificates (STCs, which are required for some parts that introduce major changes). Responding to engine manufacturers that had attempted to limit support of their products if PMA and STC parts were installed, the FAA confirmed that unless otherwise specified, PMA and STC parts are fully interchangeable with the originals, since they are “thoroughly evaluated for compliance with respect to any changes they introduce and their effect on the original type design.”

In some cases, PMA parts are essentially identical to the ones they replace. EXTEX Engineered Products, a Kaman company, manufactures PMA parts for a variety of helicopter engine and airframe models, often using the same supply chain as the OEMs, and sometimes under license from them.

“Effectively, we’re making the same product with the type of same material with the same design dimensions and all these things under more robust testing requirements, in some cases on the exact same production line as the OEMs. And at the end of that manufacturing line, ours simply gets a different part number,” explained EXTEX sales and business development manager Reid Selover.

While Parker LORD generally works with OEMs, they also develop PMA parts in response to market demand. According to Rodolphe Leroy, the biggest driver for their PMA parts is usually limited availability of the OEM originals. Parker LORD Photo

Parker LORD, a specialist in elastomeric components, is also a supplier to helicopter OEMs in addition to offering a line of PMA parts. According to Francois Magnan, a customer manager for Parker LORD’s Aerospace & Defense Aftermarket business, his company is careful to respect its contracts by firewalling any team that is developing a PMA version of a part it manufactures for OEMs.

“When we do a PMA, it’s very clean,” he said. “It’s very much reverse engineered, which means we’re not using the OEM data that we have within the building.” Nevertheless, those PMA parts leverage all of the technical expertise and quality processes that Parker LORD’s OEM customers have come to rely on — and then some.

“We go above and beyond what the FAA requires, due to the fact that we know how those parts are constructed, we know how the parts react in the field,” explained Rodolphe Leroy, director of aftermarket sales and business development. “We want to make sure that we offer a product that has ‘belt and suspenders,’ because our reputation is at stake if we produce a PMA that’s not going to be per the expectation of the market.”

Van Horn Aviation’s composite 206 series tail rotor blades are said to reduce overall aircraft noise by up to 40 percent. VHA Photo

Contrary to their early reputation as inferior substitutes for OEM parts, today’s PMA products often incorporate substantial improvements over the originals. “Now when we’re producing a part we can use the most current industry standards,” noted Aerometals’ Symon. When it comes to some older parts, she said, “getting a PMA allows us to upgrade some of the production methodologies and processes that we go through that allow us to increase the life of the part.”

Arizona-based Van Horn Aviation specializes in durable composite main and tail rotor blades that far outlast the metal blades they replace. “I think it’s proven itself that the PMA-STC world adds value to the customer,” said company president Dean Rosenlof. “If it didn’t, there would be no PMAs or STCs or companies out there sustaining products.”

According to Rosenlof, much of PMA and STC holders’ competitive advantage comes from their relatively narrow focus on a limited product line. Unlike large OEMs that must coordinate the development and support of many parts across multiple divisions, many PMA makers can optimize for just a handful of product types.

“All we do is one thing and all our focus is one product,” he said. “That’s it, there’s nothing else. I can’t lean on another division, all I can do is support the customer with our particular product.”

PMA parts can be especially helpful for operating legacy aircraft that are no longer well supported by the OEM. “I think that as time goes on, and this old fleet gets older, one of the things that keep these things flying is a good robust aftermarket,” said Selover of EXTEX. “Generally speaking, we’re focused on legacy aircraft, things that are traditionally under-supported by the OEMs because the OEMs want to do new stuff.”

Growing acceptance

Today, with years of service behind them, PMA parts have lost much of their earlier stigma.

A cross section of the DART Aerospace Roun-i-Beam skid tube

“We find that most companies now accept PMA parts, with smaller companies generally being the most likely to use PMA parts. There are also numerous medium and large helicopter operators that not only accept PMA parts, but also actively work with PMA suppliers to increase PMA part availability,” said Eric Wolff, vice president of sales and business development for Airwolf Aerospace. Airwolf entered the helicopter PMA-STC market in 2011, initially with tension-torsion (TT) straps for Bell 206 models. It has since expanded its product line with TT straps for additional helicopter types, Bell 407 main rotor head elastomerics, and other products.

Many OEMs have also softened their rhetoric against PMA parts, acknowledging that the PMA-STC market is here to stay and can actually improve the business case for their products. Notably, for Vertical’s 2021 Helicopter & Engine Manufacturers Survey, MD Helicopters said that PMA is “essential in the support and service of our fleet and is a support discriminator. We have worked closely with PMA providers to develop relationships and assist them in their efforts, in compliance with all laws, regulations, and processes.”

Like everyone else in the industry, PMA-STC holders felt the impact of the Covid-19 pandemic, with many seeing sales drop off sharply in 2020 with the abrupt curtailment of flying activity. While demand has since rebounded, they’re now contending with the widespread supply chain shortages that have afflicted the global economy.

“The Omicron outbreak sent the industry into yet another disruption balance between supply chain and demand,” Toufic Haidar, global head of supply chain for DART Aerospace, told Vertical by email in early March. “Our teams are working tirelessly to counterattack these disruptions and increase in costs.”

The closure of some small shops has also forced companies like Aerometals to expand their in-house capabilities and seek outside vendors farther afield. According to Symon, “whereas in the past we might have been able to use a heat treater that was more local, or maybe in Southern California, we’re now having to go out of the state to find other vendors.”

The City of San Diego Fire-Rescue Air Operations Department was the launch customer for Aerometals’ Engine Inlet Barrier Filter for the UH-60/S-70i. Mike Reyno Photo

A longer-term headwind facing the industry is the increasing difficulty of certifying new products, which is not specific to any particular manufacturer. “Regulations haven’t changed much in 25 years . . . how it’s interpreted and how it’s measured [has],” commented Selover.

According to multiple sources, certification challenges exist not only in the U.S., but also in Europe, where the process of getting validation from the European Union Aviation Safety Agency (EASA) can be long and difficult. The situation reflects the broader pressure that regulators are under to intensify their certification scrutiny, particularly given the black eye the FAA received from the Boeing 737 Max tragedies.

For the PMA-STC market as a whole, regulatory attention has historically been a good thing, insofar as it has built confidence in PMA parts and ensured their equivalent standing to the OEM originals. However, the current climate is now discouraging some PMA-STC holders from pursuing certain products or geographic markets.

Van Horn Aviation, for example, has given up on pursuing EASA validation for its Bell 206 main rotor blades, which are fully certified by the FAA but ran into a wall with the European regulator.

“I have great European customers flying our tail rotor blades that are just begging for the mains,” said Rosenlof. “But after two years of paying exorbitant EASA fees with little movement towards obtaining certification, we decided to halt the project. We may try again when the political climate is more favorable.”

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  1. Avatar for Elan Head

1 Comment

  1. Great article. PMA parts are sometimes perform better and last longer than the OEM parts,specifically when the original design is improved.

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