Every time an FAA-certificated mechanic, repairman, or other authorized person performs maintenance, preventive maintenance, rebuilding, or alteration on an aircraft, airframe, aircraft engine, propeller, appliance, or component part, that work must be documented. This is not just paperwork — it is the legal record that proves airworthiness was addressed and who accepted responsibility. Title 14 of the Code of Federal Regulations, Part 43, Section 43.9 establishes the minimum content requirements for those maintenance record entries. Understanding exactly what must appear in each entry is essential for any Aviation Maintenance Technician (AMT) and is a core topic on the FAA AMT General Knowledge Test.
The underlying philosophy is straightforward: any future maintainer, inspector, or owner must be able to read a logbook or work order and understand precisely what was done, when it was done, whether it returned the aircraft to an airworthy condition, and who is legally accountable. A vague or incomplete entry does not serve that purpose and may constitute a regulatory violation in itself.
The Four Required Elements of a 43.9 Entry
Section 43.9(a) of Title 14 CFR specifies that each record entry for maintenance, preventive maintenance, rebuilding, or alteration must contain four elements. Every one of them is mandatory — not suggested:
- Description of work performed. The entry must describe the work done in enough detail that the nature of the maintenance action is clear. Vague language such as "inspected and found okay" is generally insufficient. The description should identify which component or system was worked on, what was found, and what was accomplished. If a part was replaced, the replacement part's part number and serial number (where applicable) should be included, though 43.9 itself focuses on the description of the work rather than mandating part numbers as a separate line item.
- Date of completion. The entry must state the date the work was completed — not the date it was started. This date is critical for tracking intervals such as annual inspection due dates, 100-hour inspection intervals, and component time limits. The date is typically recorded in month/day/year format, though the regulation does not specify a format, and many operators follow military-style date notation.
- Name of the person performing the work, if other than the certificate holder signing the entry. The regulation requires this name to be identified when the person performing the work is not the same person approving it for return to service. In practice, when the same certificated individual both performs and approves the work, the signature block satisfies this requirement by identifying that person.
- Certificate number, type of certificate held, and signature. The person approving the aircraft or article for return to service must sign the entry and include their certificate type (e.g., Airframe and Powerplant, Repairman, etc.) and certificate number. This signature is the legal act of approval for return to service. Without it, no maintenance action under Part 43 is complete from a regulatory standpoint.
These four elements work together as a package. An entry missing any one of them is non-compliant, regardless of how thorough the rest of the entry may be.
The Return-to-Service Statement
Beyond describing what was done, 43.9(a) also requires that the entry include a statement that the work was performed in accordance with the applicable regulations and that the aircraft or article is approved for return to service. This is sometimes called the return-to-service (RTS) statement or approval statement. The typical language used in logbooks reads something like: "I certify that the work described above was performed in accordance with 14 CFR Part 43 and that the aircraft/article is approved for return to service."
This statement carries legal weight. By signing it, the certificated individual is attesting that the maintenance was performed correctly, that the applicable maintenance data (such as the manufacturer's maintenance manual, Airworthiness Directives, or FAA-approved data) was used, and that the aircraft or article meets airworthy standards. A mechanic who signs a return-to-service statement for work not performed in accordance with applicable data can face certificate action or civil penalty.
Where Entries Are Made
Section 43.9 specifies that the record entry must be made in the maintenance record of the aircraft, airframe, aircraft engine, propeller, appliance, or component part on which the work was performed. In practice, this usually means the aircraft logbook, engine logbook, propeller logbook, or a separate appliance record, depending on what was worked on. Some large or complex aircraft use computerized maintenance tracking systems or maintenance work orders that are maintained as the official records — these are acceptable so long as the 43.9 content requirements are met.
It is important to note that for major repairs and major alterations, the requirements go beyond 43.9. Those actions must also be documented on FAA Form 337 (Major Repair and Alteration), per 14 CFR 43.9(d) and Part 43 Appendix B. The Form 337 is a separate, dual-purpose document — one copy goes to the FAA, and one copy is retained with the aircraft records. Section 43.9 itself governs the logbook entry, while the Form 337 requirement is an additional layer specific to major work.
Preventive Maintenance Entries by Pilots
Certificated pilots who hold at least a private pilot certificate may perform certain preventive maintenance tasks on aircraft they own or operate, as listed in 14 CFR Part 43 Appendix A(c). When a pilot performs such preventive maintenance, they must also make a 43.9-compliant record entry. The entry must include the same four elements: description of work, date of completion, the name of the person performing the work if other than the certificate holder signing, and the pilot's certificate type and number with signature. Many student pilots are surprised to learn that pilots — not just mechanics — are subject to these record-keeping requirements when they perform authorized maintenance tasks.
Why These Requirements Matter for Safety and Accountability
Maintenance records serve multiple critical functions in the aviation system. First, they create a continuous airworthiness history for an aircraft. When an accident or incident occurs, investigators examine maintenance records to determine whether prior work was performed correctly and whether any systemic issues exist. Incomplete or falsified records can obscure safety-critical information.
Second, they establish legal accountability. The signature on a 43.9 entry is a regulatory act. If an aircraft departs in an unairworthy condition after maintenance, investigators and enforcement personnel can trace responsibility directly to the person who signed the return-to-service entry. This is why many experienced AMTs carefully review their entries — once signed, that record reflects their professional and legal judgment.
Third, maintenance records support scheduling and compliance tracking. Time-limited components, recurring inspections, and Airworthiness Directive compliance intervals all depend on accurate dates and descriptions in the records. An incorrect or missing date can cause an operator to unknowingly exceed an inspection interval, creating an airworthiness violation.
Key Numbers and Rules
- 14 CFR 43.9 — the governing regulation for maintenance record entry content for all maintenance, preventive maintenance, rebuilding, and alteration.
- Four required elements: (1) description of work performed, (2) date of completion, (3) name of person performing the work, if other than the certificate holder signing the entry, (4) certificate type, number, and signature.
- Return-to-service statement is required as part of the entry — not optional.
- Major repairs and alterations additionally require FAA Form 337, per 14 CFR 43.9(d) and Appendix B to Part 43.
- Pilots performing preventive maintenance under Appendix A(c) must also comply with 43.9 record-keeping requirements.
- Entries must be made in the record of the specific article worked on — e.g., engine logbook for engine work, airframe logbook for airframe work.
- There is no specified format for how entries must look, only minimum content requirements — but the content must be clear and complete.
Common Test Traps
- Confusing 43.9 with 43.11. Section 43.11 governs the content of inspection entries specifically (100-hour, annual, etc.), which require a slightly different set of statements. The FAA test may present a question about an inspection entry and expect you to recognize that 43.11 — not 43.9 — applies. However, 43.9 governs routine maintenance entries, not inspection sign-offs.
- Thinking a description alone is enough. Many test takers underestimate the return-to-service statement requirement. It is a legally required part of every 43.9 entry. An entry with a great description but no RTS statement is non-compliant.
- Assuming the date of entry is the date of work. The required date is the date of completion of the work, not the date the logbook entry is physically written (though these are often the same). A common mistake is backdating or forward-dating entries.
- Overlooking the pilot's record-keeping obligation. Some test questions ask who must make maintenance record entries. The answer includes pilots performing authorized preventive maintenance, not just mechanics and repairmen.
- Forgetting that major repairs require Form 337 in addition to a logbook entry. The 43.9 logbook entry alone is not sufficient for major repairs or major alterations — both the logbook entry and the FAA Form 337 are required.