14 C.F.R. § 27.303 Factor of safety.
Title 14 - Aeronautics and Space
Unless otherwise provided, a factor of safety of 1.5 must be used. This factor applies to external and inertia loads unless its application to the resulting internal stresses is more conservative.
Title 14: Aeronautics and Space
PART 27—AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT
Subpart C—Strength Requirements
General
§ 27.303 Factor of safety.