(a) The suitability and durability of materials used for parts, the failure of which could adversely affect safety, must--
(1) Be established by experience or tests;
(2) Meet approved specifications that ensure their having the strength and other properties assumed in the design data; and
(3) Take into account the effects of environmental conditions, such as temperature and humidity, expected in service.
(b) Workmanship must be of a high standard. [Doc. No. 4080, 29 FR 17955, Dec. 18, 1964, as amended by Amdt. 23-17, 41 FR 55464, Dec. 20, 1976; Amdt. 23-23, 43 FR 50592, Oct. 10, 1978]