An FAA repair specification is an approved document that defines the methodology for performing a major repair on an aircraft part or component. Unlike a Form 337 field approval, a repair specification is reusable — it can be applied to multiple articles of the same part number without requiring new FAA approval each time. It is issued under 14 CFR Part 43 and authorizes specific repair techniques for parts that cannot be repaired under standard airworthiness standards alone.

A major repair is a repair that, if improperly done, might appreciably affect weight, balance, structural strength, performance, powerplant operation, flight characteristics, or other airworthiness qualities — or that is not done according to accepted practices or cannot be done by elementary operations. Major repairs require FAA approval through either a Form 337 field approval (one-time) or a repair specification (reusable, multi-aircraft).

A repair specification authorizes a specific facility to perform a specific repair on a specific part. It is facility-bound and process-bound. A PMA authorizes the holder to manufacture and sell the repaired or replacement article to any operator worldwide. If your facility has a proven repair process with strong engineering data, converting that repair spec into a PMA can unlock significant commercial value beyond your current customer base.

Yes — this is one of our core service offerings. If your facility has a proven proprietary repair process, we assess the existing engineering data and identify the gap between your current repair specification and FAA PMA requirements. The conversion typically involves formalizing drawings, reframing substantiation under AC 21.303, and scoping the quality system to Part 21.137. Learn more about our PMA certification services.

Repair specifications can be developed for virtually any propulsion component that undergoes major repairs, including turbine engine hot section components, fuel system hardware, accessory gearboxes, engine cases, bearings, structural fittings, and fuel nozzles. Our team specializes in propulsion components and holds Part 33 DER delegations covering the full scope of aircraft engine certification.

FAA test cell correlation is the process of demonstrating that an engine test cell produces performance data consistent with a reference (master) test cell within an acceptable tolerance. It is required under 14 CFR 43.2 for MRO facilities that test overhauled engines, ensuring that engines meet minimum rated performance requirements before return to service.

Any FAA-certificated gas turbine engine type that is overhauled and tested may require test cell correlation, including APUs (auxiliary power units), turbofan and turbojet engines, and turboprop and turboshaft engines. APU test cell correlation is a rapidly growing area — aging regional and business aviation fleets are driving increased demand for APU overhaul capability and FAA-approved test cell support.

A test cell correlation package documents the test cell instrumentation, the correlation test procedure, the raw test data, and the statistical analysis demonstrating equivalence to the reference cell within acceptable tolerances. The completed package is submitted to the FAA for approval.

SAE EG-1E is the Gas Turbine Test Facilities and Equipment Committee — the industry body that develops the standards governing gas turbine engine test procedures and facilities. Membership means direct participation in the development of the standards that FAA reviewers reference when evaluating test cell correlation packages. Our founder is an active SAE EG-1E committee member.

Yes. If your team has developed the correlation data and package, we offer independent expert review without requiring a full rebuild. We assess your existing package against FAA and OEM requirements, identify any gaps, and support the submittal process. This is often the fastest path to approval when solid data already exists.

A Parts Manufacturer Approval (PMA) is an FAA approval that allows a manufacturer to produce and sell replacement parts for type-certificated aircraft, engines, and propellers. It grants combined design, production, and installation authority in a single document under 14 CFR Part 21, Subpart K.

A typical FAA PMA certification timeline runs 6 to 18 months depending on part complexity, compliance path, and submission quality. Programs with complete, well-organized packages and early DER involvement consistently achieve faster approvals with fewer FAA comment cycles — which can each add 4–8 weeks.

Test & Computations (T&C) demonstrates that a PMA part meets airworthiness standards through analysis, testing, and engineering data. Identicality demonstrates that the part is identical in design to one already approved under a Type Certificate or STC. The right path depends on your part type, available data, and timeline — a DER determines the most efficient compliant route.

A Designated Engineering Representative (DER) is required to approve the engineering data in your PMA submission package. Working with an in-house DER — rather than coordinating externally — reduces delays, improves package quality, and gives you direct access to the person accountable for the Form 8110-3 approval.

Yes. MROs with proven proprietary repair processes often have most of the engineering data needed for a PMA already. The conversion involves formalizing drawings, framing the substantiation under AC 21.303, and aligning the quality system to Part 21.137. Prime Propulsion specializes in this MRO repair-to-PMA conversion path — learn more about our Repair Specification services or contact us to discuss your process.