CFR /  Title 14  /  Part 27  /  Sec. 27.659 Mass balance.

(a) The rotors and blades must be mass balanced as necessary to--

(1) Prevent excessive vibration; and

(2) Prevent flutter at any speed up to the maximum forward speed.

(b) The structural integrity of the mass balance installation must be substantiated. [Amdt. 27-2, 33 FR 963, Jan. 26, 1968]