14 C.F.R. § 31.37 Fastenings.
Title 14 - Aeronautics and Space
Only approved bolts, pins, screws, and rivets may be used in the structure. Approved locking devices or methods must be used for all these bolts, pins, and screws, unless the installation is shown to be free from vibration. Self-locking nuts may not be used on bolts that are subject to rotation in service.
Title 14: Aeronautics and Space
PART 31—AIRWORTHINESS STANDARDS: MANNED FREE BALLOONS
Subpart D—Design Construction
§ 31.37 Fastenings.