title-14-part-29-sec29-427

590

14 CFR Ch. I (1–1–24 Edition)

§ 29.397

limit pilot forces prescribed in § 29.397
in conjunction with the forces output
of each normally energized power de-
vice, including any single power boost
or actuator system failure;

(3) If the system design or the normal

operating loads are such that a part of
the system cannot react to the limit
pilot forces prescribed in § 29.397, that
part of the system must be designed to
withstand the maximum loads that can
be obtained in normal operation. The
minimum design loads must, in any
case, provide a rugged system for serv-
ice use, including consideration of fa-
tigue, jamming, ground gusts, control
inertia, and friction loads. In the ab-
sence of a rational analysis, the design
loads resulting from 0.60 of the speci-
fied limit pilot forces are acceptable
minimum design loads; and

(4) If operational loads may be ex-

ceeded through jamming, ground gusts,
control inertia, or friction, the system
must withstand the limit pilot forces
specified in § 29.397, without yielding.

[Doc. No. 5084, 29 FR 16150, Dec. 3, 1964, as
amended by Amdt. 29–26, 55 FR 8002, Mar. 6,
1990]

§ 29.397

Limit pilot forces and torques.

(a) Except as provided in paragraph

(b) of this section, the limit pilot
forces are as follows:

(1) For foot controls, 130 pounds.
(2) For stick controls, 100 pounds fore

and aft, and 67 pounds laterally.

(b) For flap, tab, stabilizer, rotor

brake, and landing gear operating con-
trols, the following apply (R = radius in
inches):

(1) Crank wheel, and lever controls, [1

+ R]/3

50 pounds, but not less than 50

pounds nor more than 100 pounds for
hand operated controls or 130 pounds
for foot operated controls, applied at
any angle within 20 degrees of the
plane of motion of the control.

(2) Twist controls, 80R inch-pounds.

[Amdt. 29–12, 41 FR 55471, Dec. 20, 1976, as
amended by Amdt. 29–47, 66 FR 23538, May 9,
2001]

§ 29.399

Dual control system.

Each dual primary flight control sys-

tem must be able to withstand the
loads that result when pilot forces not
less than 0.75 times those obtained
under § 29.395 are applied—

(a) In opposition; and
(b) In the same direction.

§ 29.411

Ground clearance: tail rotor

guard.

(a) It must be impossible for the tail

rotor to contact the landing surface
during a normal landing.

(b) If a tail rotor guard is required to

show compliance with paragraph (a) of
this section—

(1) Suitable design loads must be es-

tablished for the guard: and

(2) The guard and its supporting

structure must be designed to with-
stand those loads.

§ 29.427

Unsymmetrical loads.

(a) Horizontal tail surfaces and their

supporting structure must be designed
for unsymmetrical loads arising from
yawing and rotor wake effects in com-
bination with the prescribed flight con-
ditions.

(b) To meet the design criteria of

paragraph (a) of this section, in the ab-
sence of more rational data, both of the
following must be met:

(1) One hundred percent of the max-

imum loading from the symmetrical
flight conditions acts on the surface on
one side of the plane of symmetry, and
no loading acts on the other side.

(2) Fifty percent of the maximum

loading from the symmetrical flight
conditions acts on the surface on each
side of the plane of symmetry, in oppo-
site directions.

where the horizontal tail surfaces are
supported by the vertical tail surfaces,
the vertical tail surfaces and sup-
porting structure must be designed for
the combined vertical and horizontal
surface loads resulting from each pre-
scribed flight condition, considered
separately. The flight conditions must
be selected so that the maximum de-
sign loads are obtained on each surface.
In the absence of more rational data,
the unsymmetrical horizontal tail sur-
face loading distributions described in
this section must be assumed.

[Amdt. 27–26, 55 FR 8002, Mar. 6, 1990, as
amended by Amdt. 29–31, 55 FR 38966, Sept.
21, 1990]

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591

Federal Aviation Administration, DOT

§ 29.481

ROUND

OADS

§ 29.471

General.

(a)

Loads and equilibrium. For limit

ground loads—

(1) The limit ground loads obtained

in the landing conditions in this part
must be considered to be external loads
that would occur in the rotorcraft
structure if it were acting as a rigid
body; and

(2) In each specified landing condi-

tion, the external loads must be placed
in equilibrium with linear and angular
inertia loads in a rational or conserv-
ative manner.

(b)

Critical centers of gravity. The crit-

ical centers of gravity within the range
for which certification is requested
must be selected so that the maximum
design loads are obtained in each land-
ing gear element.

§ 29.473

Ground loading conditions

and assumptions.

(a) For specified landing conditions,

a design maximum weight must be
used that is not less than the max-
imum weight. A rotor lift may be as-
sumed to act through the center of
gravity throughout the landing impact.
This lift may not exceed two-thirds of
the design maximum weight.

(b) Unless otherwise prescribed, for

each specified landing condition, the
rotorcraft must be designed for a limit
load factor of not less than the limit
inertia load factor substantiated under
§ 29.725.

for additional or supplementary energy
absorption may not fail under loads es-
tablished in the tests prescribed in
§§ 29.725 and 29.727, but the factor of
safety prescribed in § 29.303 need not be
used.

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

§ 29.475

Tires and shock absorbers.

Unless otherwise prescribed, for each

specified landing condition, the tires
must be assumed to be in their static
position and the shock absorbers to be
in their most critical position.

§ 29.477

Landing gear arrangement.

Sections 29.235, 29.479 through 29.485,

and 29.493 apply to landing gear with

two wheels aft, and one or more wheels
forward, of the center of gravity.

§ 29.479

Level landing conditions.

(a)

Attitudes. Under each of the load-

ing conditions prescribed in paragraph
(b) of this section, the rotorcraft is as-
sumed to be in each of the following
level landing attitudes:

(1) An attitude in which each wheel

contacts the ground simultaneously.

(2) An attitude in which the aft

wheels contact the ground with the for-
ward wheels just clear of the ground.

(b)

Loading conditions. The rotorcraft

must be designed for the following
landing loading conditions:

(1) Vertical loads applied under

§ 29.471.

(2) The loads resulting from a com-

bination of the loads applied under
paragraph (b)(1) of this section with
drag loads at each wheel of not less
than 25 percent of the vertical load at
that wheel.

(3) The vertical load at the instant of

peak drag load combined with a drag
component simulating the forces re-
quired to accelerate the wheel rolling
assembly up to the specified ground
speed, with—

(i) The ground speed for determina-

tion of the spin-up loads being at least
75 percent of the optimum forward
flight speed for minimum rate of de-
scent in autorotation; and

(ii) The loading conditions of para-

graph (b) applied to the landing gear
and its attaching structure only.

(4) If there are two wheels forward, a

distribution of the loads applied to
those wheels under paragraphs (b)(1)
and (2) of this section in a ratio of
40:60.

(c)

Pitching moments. Pitching mo-

ments are assumed to be resisted by—

(1) In the case of the attitude in para-

graph (a)(1) of this section, the forward
landing gear; and

(2) In the case of the attitude in para-

graph (a)(2) of this section, the angular
inertia forces.