14 CFR § 135.64
Retention of contracts and amendments: Commercial operators who conduct intrastate operations for compensation or hire
July 13, 2020
Each commercial operator who conducts intrastate operations for compensation or hire shall keep a copy of each written contract under which it provides services as a commercial operator for a period of at least one year after the date of execution of the contract. In the case of an oral contract, it shall keep a memorandum stating its elements, and of any amendments to it, for a period of at least one year after the execution of that contract or change.
[Doc. No. 28154, 60 FR 65939, Dec. 20, 1995, as amended by Amdt. 135-65, 61 FR 30435, June 14, 1996; Amdt. 135-66, 62 FR 13257, Mar. 19, 1997]