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14 CFR Ch. I (1–1–19 Edition) 

§ 25.703 

engines on one side of the plane of sym-
metry 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 de-
signed for the loads imposed when the 
wing flaps or slats on one side are car-
rying the most severe load occurring in 
the prescribed symmetrical conditions 
and those on the other side are car-
rying not more than 80 percent of that 

(d) The interconnection must be de-

signed for the loads resulting when 
interconnected flap or slat surfaces on 
one side of the plane of symmetry are 
jammed and immovable while the sur-
faces on the other side are free to move 
and the full power of the surface actu-
ating system is applied. 

[Amdt. 25–72, 55 FR 29777, July 20, 1990] 

§ 25.703

Takeoff warning system. 

A takeoff warning system must be in-

stalled and must meet the following re-

(a) The system must provide to the 

pilots an aural warning that is auto-
matically activated during the initial 
portion of the takeoff roll if the air-
plane is in a configuration, including 
any of the following, that would not 
allow a safe takeoff: 

(1) The wing flaps or leading edge de-

vices are not within the approved range 
of takeoff positions. 

(2) Wing spoilers (except lateral con-

trol spoilers meeting the requirements 
of § 25.671), speed brakes, or longitu-
dinal trim devices are in a position 
that would not allow a safe takeoff. 

(b) The warning required by para-

graph (a) of this section must continue 

(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 take-

off; or 

(4) The warning is manually deacti-

vated 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] 






§ 25.721


(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 as-
sumed to act in the upward and aft di-
rections in combination with side loads 
acting inboard and outboard. In the ab-
sence of a more rational analysis, the 
side loads must be assumed to be up to 
20 percent of the vertical load or 20 per-
cent of the drag load, whichever is 

(b) The airplane must be designed to 

avoid any rupture leading to the spill-
age of enough fuel to constitute a fire 
hazard as a result of a wheels-up land-
ing on a paved runway, under the fol-
lowing 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 re-

tracted; 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 20


yaw angle; and 

(ii) Any one or more landing gear 

legs not extended and with 0




(c) For configurations where the en-

gine nacelle is likely to come into con-
tact 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 pre-
dominantly 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] 

§ 25.723

Shock absorption tests. 

(a) The analytical representation of 

the landing gear dynamic characteris-
tics that is used in determining the 

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