title-14-part-29-sec29-729

608

14 CFR Ch. I (1–1–24 Edition)

§ 29.723

source (such as hydrualic pumps), and
such items as valves, lines, and actu-
ators.

(such as piston rods and links), and the
jamming of power cylinders, must be
considered unless they are extremely
improbable.

ANDING

EAR

§ 29.723

Shock absorption tests.

The landing inertia load factor and

the reserve energy absorption capacity
of the landing gear must be substan-
tiated by the tests prescribed in
§§ 29.725 and 29.727, respectively. These
tests must be conducted on the com-
plete rotorcraft or on units consisting
of wheel, tire, and shock absorber in
their proper relation.

§ 29.725

Limit drop test.

The limit drop test must be con-

ducted as follows:

(a) The drop height must be at least

8 inches.

(b) If considered, the rotor lift speci-

fied in § 29.473(a) must be introduced
into the drop test by appropriate en-
ergy absorbing devices or by the use of
an effective mass.

tested in the attitude simulating the
landing condition that is most critical
from the standpoint of the energy to be
absorbed by it.

(d) When an effective mass is used in

showing compliance with paragraph (b)
of this section, the following formulae
may be used instead of more rational
computations.

× + −

(

)

;

1 L

and

where:

= the effective weight to be used in the

drop test (lbs.).

W = W

for main gear units (lbs.), equal to

the static reaction on the particular unit
with the rotorcraft in the most critical
attitude. A rational method may be used
in computing a main gear static reac-
tion, taking into consideration the mo-
ment arm between the main wheel reac-
tion and the rotorcraft center of gravity.

W = W

for nose gear units (lbs.), equal to

the vertical component of the static re-

action that would exist at the nose
wheel, assuming that the mass of the
rotorcraft acts at the center of gravity
and exerts a force of 1.0

g downward and

0.25

g forward.

W = W

for tailwheel units (lbs.) equal to

whichever of the following is critical—

(1) The static weight on the tailwheel with

the rotorcraft resting on all wheels; or

(2) The vertical component of the ground

reaction that would occur at the tailwheel
assuming that the mass of the rotorcraft
acts at the center of gravity and exerts a
force of 1

g downward with the rotorcraft in

the maximum nose-up attitude considered in
the nose-up landing conditions.

h = specified free drop height (inches).
L = ratio of assumed rotor lift to the rotor-

craft weight.

d = deflection under impact of the tire (at

the proper inflation pressure) plus the
vertical component of the axle travel
(inches) relative to the drop mass.

n = limit inertia load factor.
n

= the load factor developed, during impact,

on the mass used in the drop test (i.e.,
the acceleration

dv/dt in g’s recorded in

the drop test plus 1.0).

[Doc. No. 5084, 29 FR 16150, Dec. 3, 1964, as
amended by Amdt. 29–3, 33 FR 967, Jan. 26,
1968]

§ 29.727

Reserve energy absorption

drop test.

The reserve energy absorption drop

test must be conducted as follows:

(a) The drop height must be 1.5 times

that specified in § 29.725(a).

(b) Rotor lift, where considered in a

manner similar to that prescribed in
§ 29.725(b), may not exceed 1.5 times the
lift allowed under that paragraph.

this test without collapsing. Collapse
of the landing gear occurs when a
member of the nose, tail, or main gear
will not support the rotorcraft in the
proper attitude or allows the rotorcraft
structure, other than landing gear and
external accessories, to impact the
landing surface.

[Doc. No. 5084, 29 FR 16150, Dec. 3, 1964, as
amended by Amdt. 27–26, 55 FR 8003, Mar. 6,
1990]

§ 29.729

Retracting mechanism.

For rotorcraft with retractable land-

ing gear, the following apply:

(a)

Loads. The landing gear, retract-

ing mechanism, wheel well doors, and
supporting structure must be designed
for—

VerDate Sep<11>2014

09:06 Jun 28, 2024

Jkt 262046

PO 00000

Frm 00618

Fmt 8010

Sfmt 8010

Y:\SGML\262046.XXX

262046

EC28SE91.089</MATH>

jspears on DSK121TN23PROD with CFR

609

Federal Aviation Administration, DOT

§ 29.735

(1) The loads occurring in any ma-

neuvering condition with the gear re-
tracted;

(2) The combined friction, inertia,

and air loads occurring during retrac-
tion and extension at any airspeed up
to the design maximum landing gear
operating speed; and

(3) The flight loads, including those

in yawed flight, occurring with the
gear extended at any airspeed up to the
design maximum landing gear extended
speed.

(b)

Landing gear lock. A positive

means must be provided to keep the
gear extended.

(c)

Emergency operation. When other

than manual power is used to operate
the gear, emergency means must be
provided for extending the gear in the
event of—

(1) Any reasonably probable failure in

the normal retraction system; or

(2) The failure of any single source of

hydraulic, electric, or equivalent en-
ergy.

(d)

Operation tests. The proper func-

tioning of the retracting mechanism
must be shown by operation tests.

(e)

Position indicator. There must be

means to indicate to the pilot when the
gear is secured in the extreme posi-
tions.

(f)

Control. The location and oper-

ation of the retraction control must
meet the requirements of §§ 29.777 and
29.779.

(g)

Landing gear warning. An aural or

equally effective landing gear warning
device must be provided that functions
continuously when the rotorcraft is in
a normal landing mode and the landing
gear is not fully extended and locked.
A manual shutoff capability must be
provided for the warning device and the
warning system must automatically
reset when the rotorcraft is no longer
in the landing mode.

[Doc. No. 5084, 29 FR 16150, Dec. 3, 1964, as
amended by Amdt. 29–24, 49 FR 44437, Nov. 6,
1984]

§ 29.731

Wheels.

(a) Each landing gear wheel must be

approved.

(b) The maximum static load rating

of each wheel may not be less than the
corresponding static ground reaction
with—

(1) Maximum weight; and
(2) Critical center of gravity.
(c) The maximum limit load rating of

each wheel must equal or exceed the
maximum radial limit load determined
under the applicable ground load re-
quirements of this part.

§ 29.733

Tires.

Each landing gear wheel must have a

tire—

(a) That is a proper fit on the rim of

the wheel; and

(b) Of a rating that is not exceeded

under—

(1) The design maximum weight;
(2) A load on each main wheel tire

equal to the static ground reaction cor-
responding to the critical center of
gravity; and

(3) A load on nose wheel tires (to be

compared with the dynamic rating es-
tablished for those tires) equal to the
reaction obtained at the nose wheel,
assuming that the mass of the rotor-
craft acts as the most critical center of
gravity and exerts a force of 1.0

g down-

ward and 0.25

g forward, the reactions

being distributed to the nose and main
wheels according to the principles of
statics with the drag reaction at the
ground applied only at wheels with
brakes.

able landing gear system must, at the
maximum size of the tire type expected
in service, have a clearance to sur-
rounding structure and systems that is
adequate to prevent contact between
the tire and any part of the structure
or systems.

[Doc. No. 5084, 29 FR 16150, Dec. 3, 1964, as
amended by Amdt. 29–12, 41 FR 55471, Dec. 20,
1976]

§ 29.735

Brakes.

For rotorcraft with wheel-type land-

ing gear, a braking device must be in-
stalled that is—

(a) Controllable by the pilot;
(b) Usable during power-off landings;

and

anced torque when starting or stopping
the rotor; and

VerDate Sep<11>2014

09:06 Jun 28, 2024

Jkt 262046

PO 00000

Frm 00619

Fmt 8010

Sfmt 8010

Y:\SGML\262046.XXX

262046

jspears on DSK121TN23PROD with CFR