Federal Aviation Administration, DOT

Section 29.427

horn only (with the control in the critical positions for the affected parts of
the system within the limits of its motion); and
(5) The attachment of the control
system to the control surface horn
(with the control in the critical positions for the affected parts of the system within the limits of its motion).
(b) Each primary control system, including its supporting structure, must
be designed as follows:
(1) The system must withstand loads
resulting from the limit pilot forces
prescribed in Section 29.397;
(2) Notwithstanding paragraph (b)(3)
of this section, when power-operated
actuator controls or power boost controls are used, the system must also
withstand the loads resulting from the
limit pilot forces prescribed in Section 29.397
in conjunction with the forces output
of each normally energized power device, 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 Section 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 service use, including consideration of fatigue, jamming, ground gusts, control
inertia, and friction loads. In the absence of a rational analysis, the design
loads resulting from 0.60 of the specified limit pilot forces are acceptable
minimum design loads; and
(4) If operational loads may be exceeded through jamming, ground gusts,
control inertia, or friction, the system
must withstand the limit pilot forces
specified in Section 29.397, without yielding.

spaschal on DSK3GDR082PROD with CFR

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

Section 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]

Section 29.399

Dual control system.

Each dual primary flight control system must be able to withstand the
loads that result when pilot forces not
less than 0.75 times those obtained
under Section 29.395 are applied - 
(a) In opposition; and
(b) In the same direction.
Section 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 established for the guard: and
(2) The guard and its supporting
structure must be designed to withstand those loads.
Section 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 combination with the prescribed flight conditions.
(b) To meet the design criteria of
paragraph (a) of this section, in the absence of more rational data, both of the
following must be met:
(1) One hundred percent of the maximum 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 opposite directions.

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