Except for commuter category airplanes, no person may operate a large airplane unless it meets the additional airworthiness requirements of §§ 121.213 through 121.283 and 121.307 of this chapter.

No person may operate a small airplane that has a passenger-seating configuration, excluding pilot seats, of 10 seats or more unless it is type certificated—

In the transport category;

Before July 1, 1970, in the normal category and meets special conditions issued by the Administrator for airplanes intended for use in operations under this part;

Before July 19, 1970, in the normal category and meets the additional airworthiness standards in Special Federal Aviation Regulation No. 23;

In the normal category and meets the additional airworthiness standards in appendix A;

In the normal category and complies with section 1.(a) of Special Federal Aviation Regulation No. 41;

In the normal category and complies with section 1.(b) of Special Federal Aviation Regulation No. 41;

In the commuter category; or

In the normal category, as a multi-engine certification level 4 airplane as defined in part 23 of this chapter.

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—

An airplane that is type certificated in the transport category; or

An airplane that complies with—

Appendix A of this part provided that its passenger seating configuration, excluding pilot seats, does not exceed 19 seats; or

Special Federal Aviation Regulation No. 41.

Cargo or baggage compartments:

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:

Glass fiber reinforced resin;

Materials which meet the test requirements of part 25, appendix F, part III of this chapter; or

In the case of liner installations approved prior to March 20, 1989, aluminum.

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.