14 CFR § 135.21

Each certificate holder, other than one who uses only one pilot in the certificate holder's operations, shall prepare and keep current a manual setting forth the certificate holder's procedures and policies acceptable to the Administrator. This manual must be used by the certificate holder's flight, ground, and maintenance personnel in conducting its operations. However, the Administrator may authorize a deviation from this paragraph if the Administrator finds that, because of the limited size of the operation, all or part of the manual is not necessary for guidance of flight, ground, or maintenance personnel.

Each certificate holder shall maintain at least one copy of the manual at its principal base of operations.

The manual must not be contrary to any applicable Federal regulations, foreign regulation applicable to the certificate holder's operations in foreign countries, or the certificate holder's operating certificate or operations specifications.

A copy of the manual, or appropriate portions of the manual (and changes and additions) shall be made available to maintenance and ground operations personnel by the certificate holder and furnished to—

Its flight crewmembers; and

Representatives of the Administrator assigned to the certificate holder.

Each employee of the certificate holder to whom a manual or appropriate portions of it are furnished under paragraph (d)(1) of this section shall keep it up to date with the changes and additions furnished to them.

The certificate holder must ensure the appropriate parts of the manual are accessible to flight, ground, and maintenance personnel at all times when such personnel are performing their assigned duties.

The information and instructions contained in the manual must be displayed clearly and be retrievable in the English language.