Text in force at 27-51: from 27-3, effective 17 Oct 1968.
(a) Each fuselage, landing gear, and rotor pylon structure must be designed as prescribed in this section. Resultant rotor forces may be represented as a single force applied at the rotor hub attachment point.
(b) Each structure must be designed to withstand--
(1) The critical loads prescribed in Secs. 27.337 through 27.341;
(2) The applicable ground loads prescribed in Secs. 27.235, 27.471 through 27.485, 27.493, 27.497, 27.501, 27.505, and 27.521; and
(3) The loads prescribed in Sec. 27.547 (d)(2) and (e).
(c) Auxiliary rotor thrust, and the balancing air and inertia loads occurring under accelerated flight conditions, must be considered.
(d) Each engine mount and adjacent fuselage structure must be designed to withstand the loads occurring under accelerated flight and landing conditions, including engine torque.
[(e) Deleted.]
33 FR 14105 · Source