Repair Station Ratings

A U.S. repair station's authority is defined by the ratings printed on its air agency certificate and operations specifications. Under 14 CFR 145.59, the FAA issues ratings across seven groups, and every group is subdivided into classes so that the certificate precisely describes the articles the station may maintain. The ratings are: airframe, powerplant, propeller, radio, instrument, and accessory — followed by the limited and specialized-service ratings that let a station take on work outside the standard class boundaries.

The airframe rating has two class distinctions in practice: Class 1 and Class 2 cover composite construction of small and large aircraft respectively, while Class 3 and Class 4 cover all-metal small and large aircraft. The powerplant rating is the one most maintenance managers memorize: Class 1 is reciprocating engines of 400 horsepower or less, Class 2 is reciprocating engines of more than 400 horsepower, and Class 3 is turbine engines. The propeller rating splits into Class 1 for fixed-pitch and ground-adjustable propellers and Class 2 for other propellers by make. The radio rating covers communication equipment (Class 1), navigational equipment (Class 2), and radar equipment (Class 3). The instrument rating spans mechanical, electrical, gyroscopic, and electronic instruments across Classes 1 through 4. The accessory rating covers mechanical, electrical, and electronic accessories in Classes 1 through 3.

Beyond these standard ratings, 14 CFR 145.59 provides for a limited rating and a specialized-service rating. A limited rating is granted when a station works on a particular make and model of article, or on a specific part, rather than on an entire class — for example, a station limited to one manufacturer's landing-gear assemblies. Limited ratings are how many stations do highly specific work without holding a broad class rating, and they are the ratings most often paired with a capability list. A specialized-service rating authorizes a specific process performed to a specification acceptable to the FAA, such as a particular non-destructive testing method, heat treatment, or plating process; the certificate names the specification rather than an article class.

Ratings are not merely descriptive — they are the legal ceiling on a station's work. A repair station may perform maintenance, preventive maintenance, or alterations only on articles for which it is rated and only within the scope of its operations specifications. Work performed outside the rated scope is not properly approved for return to service, no matter how competent the technicians. This is why the interplay between ratings, the operations specifications, and any capability list is central to how a Part 145 organization is managed: the ratings establish the broad authority, and the finer scoping tools narrow or extend it within the limits the FAA has approved.

It is worth distinguishing the FAA's rating scheme from the EASA equivalent, because the two systems name things differently. EASA Part 145 uses A, B, C, and D ratings — A for aircraft, B for engines, C for components, and D for specialized services such as NDT — each further subdivided by type. An organization operating under both systems, or contracting across the Atlantic, must map its FAA ratings to the corresponding EASA classes and honor whichever scope is narrower for a given article.

For a flight school or flying club, repair station ratings determine which outside shops can legally touch which parts of the fleet. When a training aircraft needs an engine overhaul, a propeller repair, or avionics work, the operator has to confirm that the chosen repair station actually holds the rating that covers that article — a powerplant Class 1 rating for a 180-horsepower trainer engine, for instance, or the correct limited rating for a specific accessory. Sending an article to an unrated station means the resulting sign-off does not properly return it to service.

For a maintenance manager or MRO, ratings are the backbone of the capability the organization sells and the compliance it must defend. Every quote, work order, and release-to-service certificate implicitly asserts that the station is rated for the work. Auditors verify that the physical work performed never strays outside the rated scope, that specialized-service ratings are backed by the named specifications and qualified personnel, and that limited ratings are supported by proper self-evaluation. Keeping the rated scope, the operations specifications, and the actual work in alignment is a daily discipline, not a once-a-year certificate check.

Aviatize's Maintenance Control and Maintenance Execution modules let an MRO or in-house maintenance organization tie every work order to the article being serviced, making it straightforward to confirm that the task falls within the station's rated scope before work begins. For flight schools that contract maintenance out, the platform records which repair station performed each package, so the operator retains clear evidence that the right rating covered the job.

Through the Digital Data & Records and Compliance & Auditing modules, Aviatize keeps the fleet's maintenance history — the articles worked, the shops used, and the release documents received — in one searchable record. That makes it easy to show an auditor that every airframe, engine, propeller, avionics, and accessory task was handled by a station rated for it.