Section 25.703

14 CFR Ch. I (1-1-19 Edition)

engines on one side of the plane of symmetry inoperative and the remaining
engines at takeoff power.
(c) For airplanes with flaps or slats
that are not subjected to slipstream
conditions, the structure must be designed for the loads imposed when the
wing flaps or slats on one side are carrying the most severe load occurring in
the prescribed symmetrical conditions
and those on the other side are carrying not more than 80 percent of that
load.
(d) The interconnection must be designed for the loads resulting when
interconnected flap or slat surfaces on
one side of the plane of symmetry are
jammed and immovable while the surfaces on the other side are free to move
and the full power of the surface actuating system is applied.
[Amdt. 25-72, 55 FR 29777, July 20, 1990]

spaschal on DSK3GDR082PROD with CFR

Section 25.703

Takeoff warning system.

A takeoff warning system must be installed and must meet the following requirements:
(a) The system must provide to the
pilots an aural warning that is automatically activated during the initial
portion of the takeoff roll if the airplane is in a configuration, including
any of the following, that would not
allow a safe takeoff:
(1) The wing flaps or leading edge devices are not within the approved range
of takeoff positions.
(2) Wing spoilers (except lateral control spoilers meeting the requirements
of Section 25.671), speed brakes, or longitudinal trim devices are in a position
that would not allow a safe takeoff.
(b) The warning required by paragraph (a) of this section must continue
until - 
(1) The configuration is changed to
allow a safe takeoff;
(2) Action is taken by the pilot to
terminate the takeoff roll;
(3) The airplane is rotated for takeoff; or
(4) The warning is manually deactivated by the pilot.
(c) The means used to activate the
system
must
function
properly
throughout the ranges of takeoff

weights, altitudes, and temperatures
for which certification is requested.
[Amdt. 25-42, 43 FR 2323, Jan. 16, 1978]

LANDING GEAR
Section 25.721

General.

(a) The landing gear system must be
designed so that when it fails due to
overloads during takeoff and landing,
the failure mode is not likely to cause
spillage of enough fuel to constitute a
fire hazard. The overloads must be assumed to act in the upward and aft directions in combination with side loads
acting inboard and outboard. In the absence of a more rational analysis, the
side loads must be assumed to be up to
20 percent of the vertical load or 20 percent of the drag load, whichever is
greater.
(b) The airplane must be designed to
avoid any rupture leading to the spillage of enough fuel to constitute a fire
hazard as a result of a wheels-up landing on a paved runway, under the following minor crash landing conditions:
(1) Impact at 5 feet-per-second
vertical velocity, with the airplane
under control, at Maximum Design
Landing Weight - 
(i) With the landing gear fully retracted; and
(ii) With any one or more landing
gear legs not extended.
(2) Sliding on the ground, with - 
(i) The landing gear fully retracted
and with up to a 20Section yaw angle; and
(ii) Any one or more landing gear
legs not extended and with 0Section yaw
angle.
(c) For configurations where the engine nacelle is likely to come into contact with the ground, the engine pylon
or engine mounting must be designed
so that when it fails due to overloads
(assuming the overloads to act predominantly in the upward direction
and separately, predominantly in the
aft direction), the failure mode is not
likely to cause the spillage of enough
fuel to constitute a fire hazard.
[Amdt. 25-139, 79 FR 59430, Oct. 2, 2014]

Section 25.723 Shock absorption tests.
(a) The analytical representation of
the landing gear dynamic characteristics that is used in determining the

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