596
14 CFR Ch. I (1–1–24 Edition)
§ 29.549
must function safely for the critical
flight load and operating conditions. A
design assessment must be performed,
including a detailed failure analysis to
identify all failures that will prevent
continued safe flight or safe landing,
and must identify the means to mini-
mize the likelihood of their occurrence.
(c) The rotor structure must be de-
signed to withstand the following loads
prescribed in §§ 29.337 through 29.341 and
29.351:
(1) Critical flight loads.
(2) Limit loads occurring under nor-
mal conditions of autorotation.
(d) The rotor structure must be de-
signed to withstand loads simulating—
(1) For the rotor blades, hubs, and
flapping hinges, the impact force of
each blade against its stop during
ground operation; and
(2) Any other critical condition ex-
pected in normal operation.
(e) The rotor structure must be de-
signed to withstand the limit torque at
any rotational speed, including zero.
In addition:
(1) The limit torque need not be
greater than the torque defined by a
torque limiting device (where pro-
vided), and may not be less than the
greater of—
(i) The maximum torque likely to be
transmitted to the rotor structure, in
either direction, by the rotor drive or
by sudden application of the rotor
brake; and
(ii) For the main rotor, the limit en-
gine torque specified in § 29.361.
(2) The limit torque must be equally
and rationally distributed to the rotor
blades.
(Secs. 604, 605, 72 Stat. 778, 49 U.S.C. 1424,
1425)
[Doc. No. 5084, 29 FR 16150, Dec. 3, 1964, as
amended by Amdt. 29–4, 33 FR 14106, Sept. 18,
1968; Amdt. 29–40, 61 FR 21907, May 10, 1996]
§ 29.549
Fuselage and rotor pylon
structures.
(a) Each fuselage and rotor pylon
structure must be designed to with-
stand—
(1) The critical loads prescribed in
§§ 29.337 through 29.341, and 29.351;
(2) The applicable ground loads pre-
scribed in §§ 29.235, 29.471 through 29.485,
29.493, 29.497, 29.505, and 29.521; and
(3) The loads prescribed in § 29.547
(d)(1) and (e)(1)(i).
(b) Auxiliary rotor thrust, the torque
reaction of each rotor drive system,
and the balancing air and inertia loads
occurring under accelerated flight con-
ditions, must be considered.
(c) Each engine mount and adjacent
fuselage structure must be designed to
withstand the loads occurring under
accelerated flight and landing condi-
tions, including engine torque.
(d) [Reserved]
(e) If approval for the use of 2
1
⁄
2
-
minute OEI power is requested, each
engine mount and adjacent structure
must be designed to withstand the
loads resulting from a limit torque
equal to 1.25 times the mean torque for
2
1
⁄
2
-minute OEI power combined with 1g
flight loads.
(Secs. 604, 605, 72 Stat. 778, 49 U.S.C. 1424,
1425)
[Doc. No. 5084, 29 FR 16150, Dec. 3, 1964, as
amended by Amdt. 29–4, 33 FR 14106, Sept. 18,
1968; Amdt. 29–26, 53 FR 34215, Sept. 2, 1988]
§ 29.551
Auxiliary lifting surfaces.
Each auxiliary lifting surface must
be designed to withstand—
(a) The critical flight loads in §§ 29.337
through 29.341, and 29.351;
(b) the applicable ground loads in
§§ 29.235, 29.471 through 29.485, 29.493,
29.505, and 29.521; and
(c) Any other critical condition ex-
pected in normal operation.
E
MERGENCY
L
ANDING
C
ONDITIONS
§ 29.561
General.
(a) The rotorcraft, although it may
be damaged in emergency landing con-
ditions on land or water, must be de-
signed as prescribed in this section to
protect the occupants under those con-
ditions.
(b) The structure must be designed to
give each occupant every reasonable
chance of escaping serious injury in a
crash landing when—
(1) Proper use is made of seats, belts,
and other safety design provisions;
(2) The wheels are retracted (where
applicable); and
(3) Each occupant and each item of
mass inside the cabin that could injure
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