The suitability and durability of materials used for parts, the failure of which could adversely affect safety, must-
(a) Be established on the basis of experience or tests;(b) Meet approved specifications that ensure their having the strength and other properties assumed in the design data; and(c) Take into account the effects of environmental conditions, such as temperature and humidity, expected in service.Doc. No. 5074, 29 FR 15695, Nov. 24, 1964, as amended by Amdt. 27-11, 41 FR 55469, Dec. 20, 1976; Amdt. 27-16, 43 FR 50599, Oct. 30, 1978 Secs. 313(a), 601, 603, 604, Federal Aviation Act of 1958 (49 U.S.C. 1354(a) , 1421 , 1423 , 1424 ) ; and sec. 6(c) of the Dept. of Transportation Act (49 U.S.C. 1655(c)