No person may operate an airplane that conforms to an amended or
supplemental type certificate issued in accordance with SFAR No. 41 for a
maximum certificated takeoff weight in excess of 12,500 pounds unless
within 1 year after issuance of the initial airworthiness certificate
under that SFAR the airplane meets the compartment interior requirements
set forth in §25.853 (a), (b), (b-1), (b-2), and (b-3) of this chapter in
effect on September 26, 1978.