When an operator, MRO, or parts distributor sends a flight-critical component out for repair, the single most important question is not price or turnaround. It is whether the shop is legally authorized to certify the part as airworthy. In the United States, that authorization comes from one place: a repair station certificate issued under Title 14 of the Code of Federal Regulations, Part 145. This guide explains what “Part 145” actually means, how these stations are rated and held accountable, how the FAA and EASA systems compare, and what a buyer should verify before placing an order.
What “Part 145” Means
“Part 145” refers to 14 CFR Part 145, the section of the U.S. federal aviation regulations that governs certificated repair stations. A repair station is an organization the Federal Aviation Administration has certificated to perform maintenance, preventive maintenance, and alterations on aircraft and aircraft articles — airframes, engines, propellers, appliances, and the components and accessories that make them up.
A facility cannot simply declare itself a repair station. It must apply to the FAA, demonstrate that it has the housing, facilities, equipment, materials, trained personnel, and technical data to perform the work it intends to do, and then operate under an approved repair station and quality manual. Once satisfied, the FAA issues an Air Agency Certificate. Attached to that certificate are operations specifications (op specs), the controlling document that states precisely what the station is authorized to do, on what articles, and under what limitations.
The key concept for a buyer is that the certificate alone does not tell the whole story. The operations specifications define the real, enforceable scope of work. A shop can hold a valid Part 145 certificate and still be entirely unauthorized to touch a particular component. Verifying scope, not just the existence of a certificate, is the heart of due diligence.
Ratings and Scope of Work
Part 145 organizes authority into ratings. The principal ratings are:
- Airframe — work on airframe structures and systems, divided into classes by aircraft size and type.
- Powerplant — work on engines, divided into classes by engine type.
- Propeller — fixed-pitch and variable-pitch propellers.
- Radio — communication, navigation, and radar equipment.
- Instrument — mechanical, electrical, gyroscopic, and electronic instruments.
- Accessory — mechanical, electrical, and electronic accessories and components.
Within these, the FAA may issue a limited rating tied to a specific make and model, a specific component, or a particular specialized service or process. Component repair stations frequently operate under limited accessory or limited airframe ratings that enumerate the exact part numbers, processes, or technologies they are approved for. For example, a station specializing in heat exchangers, valves, and environmental control system components would hold ratings and op-spec authorizations covering precisely those articles.
This is why two repair stations can both be “Part 145 certificated” yet have almost nothing in common. The rating and its supporting operations specifications, capability list, and approved data define the true boundary of what each shop may legally repair and certify.
How a Part 145 Repair Station Is Held Accountable
A Part 145 certificate is not a one-time award; it is an ongoing obligation backed by several enforceable mechanisms.
A quality system. Part 145 requires the station to establish and maintain a quality system acceptable to the FAA. This covers inspection of incoming articles, in-process and final inspection, calibration and control of measuring equipment, control of technical data, and procedures for identifying and segregating unserviceable or unsalvageable parts. The quality manual and repair station manual document how the station does all of this, and the FAA reviews and accepts them.
Approved and acceptable data. A repair station may only perform work using approved data — for example, the manufacturer’s component maintenance manual (CMM), FAA-approved technical data, supplemental type certificate data, or an FAA Designated Engineering Representative (DER) repair. A station cannot invent a repair on its own authority; the method must trace to data the FAA recognizes. This is the backbone of repeatability and traceability.
Trained, accountable personnel. The station must employ enough qualified personnel, maintain a roster of supervisory and inspection staff, and keep training and competency records. Specific individuals are accountable for returning articles to service.
The airworthiness release. When work is complete, the station does not merely ship the part back. A person authorized by the station executes an approval for return to service, certifying that the work was performed in accordance with the applicable requirements. For components, this is typically documented on FAA Form 8130-3 (Authorized Release Certificate). That form, together with the maintenance release and traceability records, is the legal evidence an operator relies on to install the part.
Continued surveillance. The FAA conducts ongoing oversight, including audits and inspections. Findings can lead to corrective action, and serious or repeated deficiencies can result in certificate suspension or revocation. Accountability is continuous, not a snapshot.
EASA Part 145 vs. FAA Part 145
The naming similarity causes constant confusion, so it is worth being precise. EASA Part 145 is a European Union regulation governing approved maintenance organizations, enforced by the European Union Aviation Safety Agency. FAA Part 145 is the U.S. regulation, enforced by the FAA. They share the same philosophy — an organization approved under a controlled quality system, using approved data, with authorized personnel issuing a maintenance release — but they are separate legal frameworks with their own terminology, forms, and audit regimes.
A shop that holds only an FAA certificate is authorized to certify work under FAA rules; that release is not automatically valid for an EU-registered aircraft. To serve both markets, a repair station obtains dual approval: an FAA Part 145 certificate and an EASA Part 145 approval. The two regulators coordinate through the U.S.–EU Bilateral Aviation Safety Agreement (BASA) and its Maintenance Annex Guidance (MAG), which lets a U.S. station hold an EASA approval based largely on FAA oversight, supplemented by a supplement that captures the EASA-specific differences in its procedures. The EASA equivalent of the return-to-service document is an EASA Form 1, which a dual-approved station can issue alongside an FAA Form 8130-3.
For a buyer, the practical takeaway is straightforward: if a component may end up on an EU-registered aircraft, confirm the shop holds an EASA Part 145 approval in addition to its FAA certificate. QTC, for instance, maintains both FAA Part 145 repair station authority and EASA Part 145 approval, so a single repair can be released into either regulatory system.
What to Look for When Qualifying a Repair Station
Treat repair station selection as a documented qualification exercise, not a phone call. At minimum, verify the following before you place an order:
- The Air Agency Certificate and operations specifications. Confirm the certificate is current and, more importantly, that the op specs and capability list actually cover your part number, make, and model.
- The relevant ratings. Match the station’s ratings to the article you need repaired — a powerplant rating does not authorize accessory work, and vice versa.
- Approved data for your repair. Confirm the shop holds or can obtain the CMM, OEM data, or DER repair authority required for the work, rather than improvising.
- Return-to-service documentation. Ensure you will receive the correct maintenance release and an FAA Form 8130-3 (and an EASA Form 1 if you need EASA acceptance).
- Quality system maturity. Look for evidence of calibration control, traceable parts handling, and a clean regulatory history.
- Bilateral coverage. If the aircraft is EU-registered or may be, confirm dual FAA and EASA approval up front.
A reputable station will make this easy. You can review the scope of our certifications and, when you are ready, request a quote with your part number so scope can be confirmed against the capability list before any work begins.
Why Certification Matters for Procurement
It is tempting to view Part 145 as paperwork that sits behind the actual repair. In procurement terms, it is the opposite: the certificate and its documentation are the product. A repaired component without a valid airworthiness release from an authorized station is, from a regulatory standpoint, not installable. The 8130-3, the maintenance release, and the traceability behind them are what allow an operator to legally return the aircraft to service and to defend that decision in an audit.
Buying from a properly rated Part 145 station — ideally one with both FAA and EASA approval when the fleet demands it — protects three things at once: airworthiness, legal compliance, and asset value. A unit returned with clean, complete certification holds its value and moves freely through the supply chain. A unit with questionable paperwork becomes a liability that can ground an aircraft. Understanding what Part 145 requires, and confirming that a shop genuinely meets it for your specific component, is the most reliable way to keep both the aircraft and the transaction on solid ground.