Text in force at 27-51: from 27-23, effective 3 Oct 1988.
[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° F under critical operating conditions including, if applicable, the engine operating conditions defined by Sec. 27.927 (b)(1) and (b)(2).]
53 FR 34212 · Source