Airworthiness release or aircraft maintenance log entry

After any maintenance, preventive maintenance, or alterations, a Part 135 operator cannot fly the aircraft until someone creates either an airworthiness release or a maintenance log entry. This documentation must follow the operator's manual procedures and certify that the work was done properly, required inspections were completed, and the aircraft is airworthy and safe to fly.

The release or entry must be signed by an authorized certificated mechanic or repairman (though repairmen can only sign for work within their certification scope). For foreign repair stations, their authorized personnel may sign instead.

Rather than writing out all the required certifications each time, operators can state in their manual that the mechanic's or repairman's signature automatically constitutes the full certification. This regulation ensures documented accountability that maintenance work returns the aircraft to an airworthy condition before flight operations resume.

*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.*