Return to Service Endorsement by Authorized Persons

Every time an aircraft is inspected, repaired, or altered, someone must take legal responsibility for the work and declare the aircraft fit to fly again. That declaration is the Return to Service (RTS) endorsement — a signature, certificate number, and statement entered in the aircraft maintenance records confirming that the work was done in accordance with FAA standards and that the aircraft (or appliance) is approved for return to service. Without it, even a perfectly performed inspection is legally incomplete, and the aircraft may not be operated.

Understanding who may sign an RTS endorsement, under what authority, and exactly what the endorsement must contain is fundamental knowledge for any Aviation Maintenance Technician (AMT). It is also the dividing line between a legal flight and a violation of 14 CFR Part 91 — territory that matters as much to mechanics as it does to pilots.

Legal Foundation: Where the Authority Comes From

The authority to return an aircraft to service flows from 14 CFR Part 43, which governs maintenance, preventive maintenance, rebuilding, and alteration of civil aircraft. Section 43.7 lists the specific persons authorized to approve an aircraft for return to service after maintenance, preventive maintenance, rebuilding, or alteration. Section 43.9 prescribes what the maintenance record entry must contain, and Section 43.11 covers the special record requirements following an inspection.

The key principle is that the authorization is task-specific. The person signing the RTS must have been authorized to perform or supervise the work in question — a mechanic cannot approve work that is outside the scope of their certificate or rating. Signing off work you were not authorized to perform is a serious regulatory violation.

Who Is Authorized to Return an Aircraft to Service

14 CFR §43.7 identifies several categories of authorized persons. Each category has defined limits:

• Certificated Airframe & Powerplant (A&P) Mechanic: May approve return to service for maintenance, preventive maintenance, and alterations they are authorized to perform, within the rating(s) held. An airframe-only mechanic cannot sign off engine work, and neither rating allows approval of major repairs or major alterations on their own.
• Certificated Mechanic with Inspection Authorization (IA): Holds an Airframe and Powerplant certificate plus an Inspection Authorization issued under 14 CFR Part 65. An IA may approve an aircraft for return to service after an annual inspection, a progressive inspection, or a major repair or major alteration performed under a FAA-approved data source. The IA is the only mechanic-level authorization that unlocks annual inspection sign-off authority.
• Certificated Repair Station: A facility certificated under 14 CFR Part 145 may return to service any article within the scope and limitations of its repair station certificate. The work must be performed and approved by a person authorized by the repair station's operations specifications. A repair station may approve major repairs and major alterations within its ratings.
• Manufacturer: The holder of a Production Approval (such as a Type Certificate, Production Certificate, or Parts Manufacturer Approval) may return to service any article manufactured under that approval. A manufacturer may also approve major repairs to articles they manufactured, to the extent authorized.
• Certificated Pilot — Preventive Maintenance Only: Under 14 CFR §43.3(g), a certificated pilot who is not a professional air carrier pilot may perform preventive maintenance on an aircraft they own or operate. Preventive maintenance is limited to simple, non-complex tasks listed in Appendix A of Part 43 (such as changing oil, replacing landing light bulbs, and servicing landing gear struts). The pilot may then approve that work for return to service — but only for those preventive maintenance tasks.
• Certificated Parachute Rigger: May approve for return to service any parachute they have maintained within the scope of their rigger certificate. (This applies to emergency parachutes installed in aircraft.)

What the Return to Service Entry Must Contain

The RTS endorsement is not just a signature — it is a legally required record entry with specific elements. 14 CFR §43.9 requires that each maintenance record entry for maintenance, preventive maintenance, rebuilding, or alteration include:

1. A description of the work performed, or a reference to data acceptable to the FAA that describes the work.
2. The date the work was completed.
3. The name of the person performing the work (if not the approving person).
4. The signature, certificate number, and kind of certificate held by the person approving the work for return to service.

For an inspection (annual or 100-hour), 14 CFR §43.11 requires a slightly different entry. If the aircraft is airworthy, the approving person signs a statement that the aircraft has been inspected in accordance with the applicable inspection (e.g., annual inspection) and found to be in an airworthy condition. If the aircraft is not airworthy, the inspector must note the discrepancies — but the aircraft may still be flown under a special flight permit (ferry permit) to a location where repairs can be made, provided the pilot in command is notified of the discrepancies.

The entry must be made in the aircraft's maintenance records — typically the airframe, engine, or propeller logbook, or a separate maintenance record system. Many operators use a dedicated work order or maintenance record form, with the logbook entry referencing that document. Whatever system is used, the regulatory content requirements of §43.9 and §43.11 must be met.

Major vs. Minor: How Classification Affects Who Can Sign

One of the most important distinctions in RTS authority is whether a repair or alteration is classified as major or minor. Appendix A of 14 CFR Part 43 defines major and minor repairs and alterations.

• Minor repairs and minor alterations may be approved for return to service by an appropriately rated A&P mechanic or a certificated repair station, provided FAA-approved or acceptable data is used.
• Major repairs and major alterations require a higher level of oversight. They must be recorded on FAA Form 337 (Major Repair and Alteration), and the RTS approval must come from an IA, a certificated repair station, or a manufacturer (as appropriate). A copy of the Form 337 is forwarded to the FAA Aircraft Registration Branch in Oklahoma City, creating a permanent record.

Misclassifying a major repair as minor — and having only an A&P (without an IA) sign it off — is a common compliance error and a favored topic on AMT knowledge tests.

Key Numbers and Rules

• §43.7 — Lists all persons authorized to approve for return to service.
• §43.9 — Prescribes content of maintenance record entries (description, date, name, signature, certificate number, certificate type).
• §43.11 — Prescribes content of inspection record entries, including the airworthy/not airworthy statement.
• §43.3(g) — Allows certificated pilots to perform and sign off preventive maintenance on their own aircraft.
• FAA Form 337 — Required for all major repairs and major alterations; one copy to the FAA, one retained in the aircraft records.
• An Inspection Authorization (IA) is required to sign off annual inspections — a plain A&P certificate, regardless of experience, is not sufficient.
• A 100-hour inspection may be approved for return to service by an A&P mechanic (no IA required), unlike an annual inspection.

Why It Matters: Safety and Legal Consequences

The RTS endorsement is the last checkpoint before an aircraft re-enters the national airspace. When an authorized person signs off an aircraft, they are personally certifying — under penalty of certificate action, civil penalty, or criminal liability — that the work meets FAA standards. Operating an aircraft without a valid RTS entry following required maintenance is a violation of 14 CFR §91.409 (for inspections) and §91.407 (operating after maintenance, preventive maintenance, rebuilding, or alteration). The pilot in command shares responsibility: §91.7 makes the PIC responsible for determining the aircraft is in an airworthy condition before flight.

For AMTs, falsifying a maintenance record — including a fraudulent RTS entry — can result in certificate suspension or revocation under 14 CFR §43.12 and potential criminal prosecution under 18 U.S.C. §1001. These are not abstract risks; the FAA's Flight Standards District Offices routinely audit maintenance records during accident investigations and ramp checks.

Common Test Traps

• Annual vs. 100-hour sign-off authority: Many students confuse these. A 100-hour inspection can be signed off by any appropriately rated A&P mechanic. An annual inspection requires an IA. The test frequently exploits this distinction.
• Preventive maintenance by pilots: A pilot may perform and sign off preventive maintenance on an aircraft they own or operate — but only the tasks listed in Appendix A of Part 43. Any task not on that list requires a mechanic.
• Major repair without Form 337: Performing a major repair and returning the aircraft to service without completing Form 337 is a violation, even if the work itself was done correctly.
• Incomplete record entry: An entry missing the certificate number, the type of certificate, or the date is not legally sufficient — even if the signature is present.
• Discrepancy found during annual: If discrepancies are found and the inspector does NOT sign off the annual as airworthy, the aircraft cannot be flown for hire, but a special flight permit may allow a ferry flight for the purpose of getting repairs made — the inspector must list the discrepancies and the pilot must be informed.