Federal Aviation Administration, DOT

Section 29.551

(2) For each float, the load share determined under paragraph (b)(1) of this
section, combined with a total side
load of 0.25 times the total vertical
load specified in paragraph (b)(1) of
this section, is applied to that float
only.
[Amdt. 29-3, 33 FR 967, Jan. 26, 1968]

MAIN COMPONENT REQUIREMENTS

spaschal on DSK3GDR082PROD with CFR

Section 29.547

(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]

Section 29.549 Fuselage
structures.

Main and tail rotor structure.

(a) A rotor is an assembly of rotating
components, which includes the rotor
hub, blades, blade dampers, the pitch
control mechanisms, and all other
parts that rotate with the assembly.
(b) Each rotor assembly must be designed as prescribed in this section and
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 minimize the likelihood of their occurrence.
(c) The rotor structure must be designed to withstand the following loads
prescribed in SectionSection 29.337 through 29.341 and
29.351:
(1) Critical flight loads.
(2) Limit loads occurring under normal conditions of autorotation.
(d) The rotor structure must be designed 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 expected in normal operation.
(e) The rotor structure must be designed 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 provided), 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 engine torque specified in Section 29.361.

and

rotor

(a) Each fuselage and rotor pylon
structure must be designed to withstand - 
(1) The critical loads prescribed in
SectionSection 29.337 through 29.341, and 29.351;
(2) The applicable ground loads prescribed in SectionSection 29.235, 29.471 through 29.485,
29.493, 29.497, 29.505, and 29.521; and
(3) The loads prescribed in Section 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 conditions, must be considered.
(c) Each engine mount and adjacent
fuselage structure must be designed to
withstand the loads occurring under
accelerated flight and landing conditions, including engine torque.
(d) [Reserved]
(e) If approval for the use of 21-2minute 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
21-2-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]

Section 29.551

Auxiliary lifting surfaces.

Each auxiliary lifting surface must
be designed to withstand - 
(a) The critical flight loads in SectionSection 29.337
through 29.341, and 29.351;
(b) the applicable ground loads in
SectionSection 29.235, 29.471 through 29.485, 29.493,
29.505, and 29.521; and
(c) Any other critical condition expected in normal operation.

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