14 CFR 27.735 - Brakes.
For rotorcraft with wheel-type landing gear, a braking device must be installed that is -
(a) Controllable by the pilot;
(b) Usable during power-off landings; and
(c) Adequate to -
(1) Counteract any normal unbalanced torque when starting or stopping the rotor; and
(2) Hold the rotorcraft parked on a 10-degree slope on a dry, smooth pavement.