14 CFR § 121.141

Each certificate holder shall keep a current approved airplane flight manual for each type of airplane that it operates except for nontransport category airplanes certificated before January 1, 1965.

In each airplane required to have an airplane flight manual in paragraph (a) of this section, the certificate holder shall carry either the manual required by § 121.133, if it contains the information required for the applicable flight manual and this information is clearly identified as flight manual requirements, or an approved Airplane Manual. If the certificate holder elects to carry the manual required by § 121.133, the certificate holder may revise the operating procedures sections and modify the presentation of performance data, except for the information required by § 38.23 of this chapter identifying compliance with the fuel efficiency requirements of part 38 of this chapter, from the applicable flight manual if the revised operating procedures and modified performance data presentation are—

Approved by the Administrator; and

Clearly identified as airplane flight manual requirements.