Every time a certificated repair station — formally called an Approved Maintenance Organization (AMO) in international terminology, but regulated in the United States as a certificated repair station under 14 CFR Part 145 — performs maintenance, preventive maintenance, or an alteration on an aircraft or aeronautical product, a formal paper trail must be created and preserved. That paper trail is the work order record. Far from being administrative busywork, the work order is a legal document that proves airworthiness was restored or maintained, connects the technician's signature to the specific task performed, and gives the aircraft owner, the FAA, and future maintainers a complete history of what was done, when, by whom, and under what authority.
For AMT General students preparing for the FAA knowledge test, understanding work order records means understanding both the regulatory foundation and the practical mechanics of how a properly documented repair station job is opened, executed, and closed out. This article walks through every layer of that process.
Regulatory Foundation
The authority for repair station recordkeeping flows primarily from two parts of Title 14 of the Code of Federal Regulations. 14 CFR Part 145 governs the certification and operation of repair stations, while 14 CFR Part 43 governs the maintenance records that must be created whenever approved maintenance work is performed on U.S.-registered aircraft.
Under 14 CFR §145.219, a certificated repair station must retain a record of all work it performed for at least two years from the date the work was approved for return to service. These records must be accessible to the FAA for inspection at any time during normal business hours. The repair station's Repair Station Manual (RSM) and, where applicable, its Quality Control Manual (QCM), must describe in detail the procedures the organization uses to generate, control, and store work order records. An FAA inspector evaluating a repair station will check not just whether records exist, but whether the procedures described in the manuals were actually followed.
Part 43 adds a complementary layer: regardless of who does the work, a maintenance record entry must be made in the aircraft's logbooks or maintenance records. The repair station's internal work order is not a substitute for the Part 43 entry — both are required, and they must be consistent with each other.
What a Work Order Contains
A properly constructed work order is a living document that grows as the job progresses. At a minimum, a repair station work order must capture the following elements:
- Customer and aircraft identification: The aircraft owner or operator's name, the aircraft make, model, and serial number, and the registration (N-number) for U.S.-registered aircraft.
- Description of work requested: A clear, written description of the maintenance, inspection, repair, or alteration being authorized by the customer. This forms the contract between the customer and the repair station.
- Work performed: A detailed narrative of what was actually accomplished — not just what was requested, but what was found and what was done. If a 100-hour inspection revealed a cracked exhaust stack that was then replaced, both the inspection and the additional repair must be documented.
- Parts and materials used: Part numbers, serial numbers (where required), and traceability documentation such as FAA Form 8130-3 (Authorized Release Certificate) for approved parts must be referenced or attached. This traceability is essential for demonstrating that only approved parts were used, as required by 14 CFR §43.13 and the repair station's own quality control procedures.
- Reference data: The technical data used to perform the work — FAA-approved manufacturer's maintenance manuals, Airworthiness Directives (ADs), Supplemental Type Certificate (STC) data, or other approved data — must be identified. This demonstrates that the work was performed in accordance with acceptable methods, techniques, and practices, the standard set by 14 CFR §43.13(a).
- Technician identification and signature: Each person who performed or supervised work must be identified, typically by name and certificate number. Their signature creates personal accountability for the work.
- Approval for Return to Service (AFRS): The authorized individual — typically a certificated repairman or an A&P mechanic with Inspection Authorization (IA), depending on the work — signs the return-to-service entry. This is the formal declaration that the aircraft or component is airworthy.
- Dates: The date work began, the date each significant step was completed, and the date the article was approved for return to service.
Work Order Lifecycle: Open to Close
Understanding the lifecycle of a work order helps technicians see how each step connects. When a customer drops off an aircraft or component, the squawk sheet or customer discrepancy list is used to open the work order. A unique work order number is assigned, creating a control number that ties all subsequent paperwork — parts requisitions, inspection sign-offs, sub-contract records — to that specific job.
As work progresses, inspection stamps or initials are applied at required inspection points defined by the repair station's QCM. Many repair stations use a traveler card or router — a sub-document attached to the work order — that moves with the part or aircraft through each work center, collecting signatures as each step is completed. This creates a sequential audit trail showing exactly who touched the work and when.
When a previously undetected discrepancy is found — called a finding — the work order must be amended to authorize additional work before the repair proceeds. The customer must typically authorize the additional scope and cost. Performing unauthorized work, even if technically correct, creates liability and documentation problems.
Once all tasks are complete and inspected, the approving authority signs the return-to-service block on the work order and makes the corresponding entry in the aircraft's official maintenance records per 14 CFR §43.9 or §43.11 (for inspections). The work order is then closed, copies are distributed (one retained by the repair station, one typically provided to the customer), and the file is archived.
Sub-Contracted Work
Repair stations frequently sub-contract specialized work — avionics calibration, propeller overhaul, non-destructive testing — to other certificated facilities. When this happens, the sub-contractor's work order and return-to-service documentation must be attached to or cross-referenced in the primary work order. The primary repair station remains responsible for the airworthiness of the completed product; it cannot simply pass liability to the sub-contractor. This is a frequently tested concept: the certificating repair station is responsible for ensuring the work performed by a sub-contractor meets all applicable standards.
Why Work Order Records Matter
Work order records matter for reasons that go well beyond compliance. First, they are the primary tool by which an FAA inspector determines whether a repair station is operating within the scope and limitations of its Operations Specifications (Op Specs). If the work order shows a task performed outside the repair station's ratings, that is evidence of a certificate violation. Second, in the event of an accident or incident, the NTSB and FAA will subpoena maintenance records. A complete, legible, accurate work order can demonstrate due diligence; a missing or falsified record can result in criminal liability. Third, for the aircraft owner, a clean work order history supports the aircraft's resale value and provides assurance that airworthiness directives have been complied with.
Key Numbers and Rules
- Retention period: Repair station records of work performed must be retained for a minimum of two years from the date the work was approved for return to service, per 14 CFR §145.219.
- Part 43 entry: Required in the aircraft maintenance record in addition to the internal work order; must include date, description of work, reference data used, and signature and certificate number of the approving individual (14 CFR §43.9).
- Approved data requirement: All maintenance must be performed per manufacturer's instructions or other FAA-approved data (14 CFR §43.13).
- Parts traceability: Approved parts must be accompanied by documentation (e.g., FAA Form 8130-3) confirming their airworthiness status.
- Scope limitation: A repair station may only perform work within the ratings listed in its Op Specs; work orders that exceed those ratings indicate a potential certificate violation.
- Return to service authority: Only appropriately certificated individuals may sign the approval for return to service; the work order must identify that individual by name and certificate number.
Common Test Traps
- Confusing the work order with the Part 43 entry: Students often assume the repair station's work order satisfies the logbook entry requirement. It does not — a separate entry in the aircraft's maintenance record per Part 43 is always required.
- Two-year retention rule: The FAA knowledge test frequently asks about the minimum retention period for repair station records. The answer is two years from the date of approval for return to service, not the lifetime of the aircraft or some other period.
- Sub-contractor responsibility: A common distractor suggests that once work is sub-contracted, the sub-contractor is solely responsible. The certificating repair station retains responsibility for the final airworthiness of the work.
- Unauthorized findings: Students may think a technician can simply fix a discovered defect and note it on the work order. In practice, additional work generally requires customer authorization before proceeding, and the work order must be amended.
- Approved vs. acceptable data: The work order must reference approved data (manufacturer's approved manuals, ADs, STCs), not merely acceptable data like generic industry standards, when performing a return-to-service action on a certificated aircraft.