Each suction lift fuel system and other fuel systems with features conducive to vapor formation must be shown by test to operate satisfactorily (within certification limits) when using fuel at a temperature of 110 [deg]F under critical operating conditions including, if applicable, the engine operating conditions defined by Sec. 27.927 (b)(1) and (b)(2). [Amdt. 27-23, 53 FR 34212, Sept. 2, 1988]