Mass balance.
CFR · 2024-01-01 · US · Title 14
(a) The rotor 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.
official document · source cfr-2024 · id 14:§ 29.659