Text in force at 25-153: from 25-46, effective 1 Dec 1978.
[(a)] The methods of fabrication used must produce a consistently sound structure. If a fabrication process (such as gluing, spot welding, or heat treating) requires close control to reach this objective, the process must be performed under an approved process specification.
[(b) Each new aircraft fabrication method must be substantiated by a test program.]
43 FR 50595 · Source