Airworthiness release or aircraft log entry

After any maintenance, preventive maintenance, or alterations, Part 121 carriers cannot operate an aircraft until either an airworthiness release or aircraft log entry is completed. This documentation must follow the carrier's manual procedures and certify that the work was done properly, all required inspections were completed, no known airworthiness issues exist, and the aircraft is safe to fly.

An authorized certificated mechanic or repairman must sign the release or entry, though they can only sign for work within their certification scope. For foreign repair stations, their authorized personnel may sign instead.

When using a release form (rather than a log entry), the carrier must give the pilot in command a copy and retain records for at least two months. Carriers may simplify their manuals by stating that an authorized signature itself constitutes the required certification rather than listing all conditions separately.

*This is a plain-English summary for study only. The official 14 CFR text on this page is controlling — always read the current regulation and consult a CFI.*