The Complexity of PMA and STC Approvals

Recently I was touring a new MRO facility and the host managers were discussing authorized repair capability, PMAs, and expediting STCs, and I recognized that it was time for refresher training on the definition and applicability of those acronyms. A...


Prototypes, approval, and conformity

“The STC applicant has the option (in most cases) of justifying their design by an engineering analysis or by testing. If engineering analysis is chosen, a factor of 1.3 must be used as a safety buffer. In other words, if the aircraft requires 9G forward-loading conditions for seats, then the engineering analysis must prove the design to be 1.3 times 9G, or 11.7G. The design is frozen once it has cleared all obstacles and passed the engineering or testing requirements. Once the decision is made to go forward, the design is executed and a prototype built, sometimes followed by several more iterations.”

The next step is to submit the project to the FAA or EASA for their review. When asked if the same AvFab team develops and manages the application process, Jeff says, “Yes, we are always the point of contact with the FAA. Some projects require a lot of communication and interaction with the FAA, and some are fairly straightforward. Occasionally when the project is extremely complex, we hire a ‘Management Designated Engineering Representative (DER)’ to oversee the project. A DER is an expert in the approval process and is recognized and trusted by the FAA. The DER oversees the process for the customer (AvFab) and submits a Form 8110-3 to the FAA recommending that a product be given approval. This helps the FAA expedite the approval.”

I asked him if they always work with the same FAA department and team for approvals. “All of our STCs go through an Aircraft Certification Office (ACO) in Wichita. We have an assigned project manager there and the review process begins with him.

“Once the data package has been blessed by the ACO, the final step in the STC process involves conformity inspections. The first item or kit is manufactured, and the FAA will perform a conformity inspection. This is primarily to ensure that the product actually matches the drawing, or is what we say it is. The installation conformity test will follow to ensure that the installation instructions are accurate. Flight testing, when required, is typically accomplished in conjunction with the installation conformity. Normally we’ll use a customer’s or sometimes we are able to use our airplanes for the flight test. After all of the i’s are dotted and t’s are crossed, awarding of the STC is imminent.”

I read that in June AvFab received STC approval from European Aviation Safety Agency (EASA) for its Beechcraft 400A three-place divan. The new STC allows installation of the two- and three-place divans in all Beechjet and Hawker Beechcraft 400 and 400A series aircraft. Asked if there were differences for getting STC approvals by the FAA and EASA, Jeff replies that EASA might come back with questions but typically the FAA STC is approved by EASA “as is.” One difference is EASA charges for its services.

Parts production

After about nine months and with approvals granted, the replacement part, kit, or new item is added to the PMA list, which allows companies to mass produce the items within their own quality control system. When the items are shipped, whether it’s a PMA replacement part or an STC new product, all documentation and authorizations are included. Once the item is produced to a certain number or level to allow for customer customization, it is presented to key high volume customers and turned over to the ad agency for marketing.

Jeff helped debunk some industry myths and gave me a better understanding of why companies get PMAs and STCs for aftermarket parts and new items. The path to producing an aftermarket product or making a change to the aircraft Type Certificate is long and rigorous with high standards and not always about the bottom line. It was apparent that AvFab strives to meet the needs of its customers, help make maintenance operations more efficient, and our industry safer through improvements in design and products.


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