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Federal Aviation Administration, DOT
§ 25.723
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-
quirements:
(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
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 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]
L
ANDING
G
EAR
§ 25.721
General.
(a) The main landing gear system
must be designed so that if it fails due
to overloads during takeoff and landing
(assuming the overloads to act in the
upward and aft directions), the failure
mode is not likely to cause—
(1) For airplanes that have passenger
seating configuration, excluding pilots
seats, of nine seats or less, the spillage
of enough fuel from any fuel system in
the fuselage to constitute a fire hazard;
and
(2) For airplanes that have a pas-
senger seating configuration, excluding
pilots seats, of 10 seats or more, the
spillage of enough fuel from any part of
the fuel system to constitute a fire
hazard.
(b) Each airplane that has a pas-
senger seating configuration excluding
pilots seats, of 10 seats or more must
be designed so that with the airplane
under control it can be landed on a
paved runway with any one or more
landing gear legs not extended without
sustaining a structural component fail-
ure that is likely to cause the spillage
of enough fuel to constitute a fire haz-
ard.
(c) Compliance with the provisions of
this section may be shown by analysis
or tests, or both.
[Amdt. 25–32, 37 FR 3969, Feb. 24, 1972]
§ 25.723
Shock absorption tests.
(a) The analytical representation of
the landing gear dynamic characteris-
tics that is used in determining the
landing loads must be validated by en-
ergy absorption tests. A range of tests
must be conducted to ensure that the
analytical representation is valid for
the design conditions specified in
§ 25.473.
(1) The configurations subjected to
energy absorption tests at limit design
conditions must include at least the
design landing weight or the design
takeoff weight, whichever produces the
greater value of landing impact energy.
(2) The test attitude of the landing
gear unit and the application of appro-
priate drag loads during the test must
simulate the airplane landing condi-
tions in a manner consistent with the
development of rational or conserv-
ative limit loads.
(b) The landing gear may not fail in
a test, demonstrating its reserve en-
ergy absorption capacity, simulating a
descent velocity of 12 f.p.s. at design
landing weight, assuming airplane lift
not greater than airplane weight act-
ing during the landing impact.
(c) In lieu of the tests prescribed in
this section, changes in previously ap-
proved design weights and minor
changes in design may be substantiated
by analyses based on previous tests
conducted on the same basic landing
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