title-14-part-29-sec29-547

595

Federal Aviation Administration, DOT

§ 29.547

(b) To provide for the case of one de-

flated tire, 60 percent of the specified
load for the gear unit must be applied
to either wheel except that the vertical
ground reaction may not be less than
the full static value.

gear unit, the transverse shift in the
load centroid, due to unsymmetrical
load distribution on the wheels, may be
neglected.

[Amdt. 29–3, 33 FR 966, Jan. 26, 1968]

ATER

OADS

§ 29.519

Hull type rotorcraft: Water-

based and amphibian.

(a)

General. For hull type rotorcraft,

the structure must be designed to with-
stand the water loading set forth in
paragraphs (b), (c), and (d) of this sec-
tion considering the most severe wave
heights and profiles for which approval
is desired. The loads for the landing
conditions of paragraphs (b) and (c) of
this section must be developed and dis-
tributed along and among the hull and
auxiliary floats, if used, in a rational
and conservative manner, assuming a
rotor lift not exceeding two-thirds of
the rotorcraft weight to act through-
out the landing impact.

(b)

Vertical landing conditions. The

rotorcraft must initially contact the
most critical wave surface at zero for-
ward speed in likely pitch and roll atti-
tudes which result in critical design
loadings. The vertical descent velocity
may not be less than 6.5 feet per second
relative to the mean water surface.

(c)

Forward speed landing conditions.

The rotorcraft must contact the most
critical wave at forward velocities
from zero up to 30 knots in likely
pitch, roll, and yaw attitudes and with
a vertical descent velocity of not less
than 6.5 feet per second relative to the
mean water surface. A maximum for-
ward velocity of less than 30 knots may
be used in design if it can be dem-
onstrated that the forward velocity se-
lected would not be exceeded in a nor-
mal one-engine-out landing.

(d)

Auxiliary float immersion condition.

In addition to the loads from the land-
ing conditions, the auxiliary float, and
its support and attaching structure in
the hull, must be designed for the load
developed by a fully immersed float un-

less it can be shown that full immer-
sion of the float is unlikely, in which
case the highest likely float buoyancy
load must be applied that considers
loading of the float immersed to create
restoring moments compensating for
upsetting moments caused by side
wind, asymmetrical rotorcraft loading,
water wave action, and rotorcraft iner-
tia.

[Amdt. 29–3, 33 FR 966, Jan. 26, 196, as amend-
ed by Amdt. 27–26, 55 FR 8002, Mar. 6, 1990]

§ 29.521

Float landing conditions.

If certification for float operation

(including float amphibian operation)
is requested, the rotorcraft, with
floats, must be designed to withstand
the following loading conditions (where
the limit load factor is determined
under § 29.473(b) or assumed to be equal
to that determined for wheel landing
gear):

(a) Up-load conditions in which—
(1) A load is applied so that, with the

rotorcraft in the static level attitude,
the resultant water reaction passes
vertically through the center of grav-
ity; and

(2) The vertical load prescribed in

paragraph (a)(1) of this section is ap-
plied simultaneously with an aft com-
ponent of 0.25 times the vertical com-
ponent

(b) A side load condition in which—
(1) A vertical load of 0.75 times the

total vertical load specified in para-
graph (a)(1) of this section is divided
equally among the floats; and

(2) For each float, the load share de-

termined 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]

AIN

OMPONENT

EQUIREMENTS

§ 29.547

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 de-

signed as prescribed in this section and

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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.

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.

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

⁄

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

⁄

-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

pected in normal operation.

MERGENCY

ANDING

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