14 CFR § 135.169 - Additional airworthiness requirements.
(1) In the transport category;
(3) Before July 19, 1970, in the normal category and meets the additional airworthiness standards in Special Federal Aviation Regulation No. 23;
(4) In the normal category and meets the additional airworthiness standards in appendix A;
(5) In the normal category and complies with section 1.(a) of Special Federal Aviation Regulation No. 41;
(6) In the normal category and complies with section 1.(b) of Special Federal Aviation Regulation No. 41;
(7) In the commuter category; or
(c) No person may operate a small airplane with a passenger seating configuration, excluding any pilot seat, of 10 seats or more, with a seating configuration greater than the maximum seating configuration used in that type airplane in operations under this part before August 19, 1977. This paragraph does not apply to -
(1) An airplane that is type certificated in the transport category; or
(2) An airplane that complies with -
(i) Appendix A of this part provided that its passenger seating configuration, excluding pilot seats, does not exceed 19 seats; or
(ii) Special Federal Aviation Regulation No. 41.
(d) Cargo or baggage compartments:
(1) After March 20, 1991, each Class C or D compartment, as defined in § 25.857 of part 25 of this chapter, greater than 200 cubic feet in volume in a transport category airplane type certificated after January 1, 1958, must have ceiling and sidewall panels which are constructed of:
(i) Glass fiber reinforced resin;
(ii) Materials which meet the test requirements of part 25, appendix F, part III of this chapter; or
(iii) In the case of liner installations approved prior to March 20, 1989, aluminum.
(2) For compliance with this paragraph, the term “liner” includes any design feature, such as a joint or fastener, which would affect the capability of the liner to safely contain a fire.