14 CFR § 29.735
Brakes
July 13, 2020
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.
[Doc. No. 5084, 29 FR 16150, Dec. 3, 1964, as amended by Amdt. 29-24, 49 FR 44437, Nov. 6, 1984]