14 CFR 121.701 : Aeronautics And Space (§ 1.1 To Parts 1311-1399) — (§ 110.1 To Part 199) — Federal Aviation Administration, Department Of Transportation (Continued) (§ 110.1 To Part 199) — Air Carriers And Operators For Compensation Or Hire: Certification And Operations (§ 110.1 To § 139.343) — Operating Requirements: Domestic, Flag, And Supplemental Operations (§ 121.1 To Appendix P To Part 121) — Records And Reports (§ 121.681 To § 121.713) — Maintenance log: Aircraft.

(a) Each person who takes action in the case of a reported or observed failure or malfunction of an airframe, engine, propeller, or appliance that is critical to the safety of flight shall make, or have made, a record of that action in the airplane's maintenance log.

(b) Each certificate holder shall have an approved procedure for keeping adequate copies of the record required in paragraph (a) of this section in the airplane in a place readily accessible to each flight crewmember and shall put that procedure in the certificate holder's manual.