14 C.F.R. § 27.661 Rotor blade clearance.
Title 14 - Aeronautics and Space
There must be enough clearance between the rotor blades and other parts of the structure to prevent the blades from striking any part of the structure during any operating condition. [Amdt. 27–2, 33 FR 963, Jan. 26, 1968]
Title 14: Aeronautics and Space
PART 27—AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT
Subpart D—Design and Construction
Rotors
§ 27.661 Rotor blade clearance.
