Section 25.731

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

 - down and locked -  if the landing gear
is not in a fully extended position, or of
 - up and locked -  if the landing gear is
not in the fully retracted position. The
switches may be located where they
are operated by the actual landing gear
locking latch or device.
(2) The flightcrew must be given an
aural warning that functions continuously, or is periodically repeated, if a
landing is attempted when the landing
gear is not locked down.
(3) The warning must be given in sufficient time to allow the landing gear
to be locked down or a go-around to be
made.
(4) There must not be a manual shutoff means readily available to the
flightcrew for the warning required by
paragraph (e)(2) of this section such
that it could be operated instinctively,
inadvertently, or by habitual reflexive
action.
(5) The system used to generate the
aural warning must be designed to
minimize false or inappropriate alerts.
(6) Failures of systems used to inhibit the landing gear aural warning,
that would prevent the warning system
from operating, must be improbable.
(7) A flightcrew alert must be provided whenever the landing gear position is not consistent with the landing
gear selector lever position.
(f) Protection of equipment on landing
gear and in wheel wells. Equipment that
is essential to the safe operation of the
airplane and that is located on the
landing gear and in wheel wells must
be protected from the damaging effects
of - 
(1) A bursting tire;
(2) A loose tire tread, unless it is
shown that a loose tire tread cannot
cause damage.
(3) Possible wheel brake temperatures.

spaschal on DSK3GDR082PROD with CFR

[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as
amended by Amdt. 25-23, 35 FR 5676, Apr. 8,
1970; Amdt. 25-42, 43 FR 2323, Jan. 16, 1978;
Amdt. 25-72, 55 FR 29777, July 20, 1990; Amdt.
25-75, 56 FR 63762, Dec. 5, 1991; Amdt. 25-136,
77 FR 1617, Jan. 11, 2012]

Section 25.731 Wheels.
(a) Each main and nose wheel must
be approved.
(b) The maximum static load rating
of each wheel may not be less than the

corresponding static ground reaction
with - 
(1) Design maximum weight; and
(2) Critical center of gravity.
(c) The maximum limit load rating of
each wheel must equal or exceed the
maximum radial limit load determined
under the applicable ground load requirements of this part.
(d) Overpressure burst prevention.
Means must be provided in each wheel
to prevent wheel failure and tire burst
that may result from excessive pressurization of the wheel and tire assembly.
(e) Braked wheels. Each braked wheel
must meet the applicable requirements
of Section 25.735.
[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as
amended by Amdt. 25-72, 55 FR 29777, July 20,
1990; Amdt. 25-107, 67 FR 20420, Apr. 24, 2002]

Section 25.733

Tires.

(a) When a landing gear axle is fitted
with a single wheel and tire assembly,
the wheel must be fitted with a suitable tire of proper fit with a speed rating approved by the Administrator
that is not exceeded under critical conditions and with a load rating approved
by the Administrator that is not exceeded under - 
(1) The loads on the main wheel tire,
corresponding to the most critical
combination of airplane weight (up to
maximum weight) and center of gravity position, and
(2) The loads corresponding to the
ground reactions in paragraph (b) of
this section, on the nose wheel tire, except as provided in paragraphs (b)(2)
and (b)(3) of this section.
(b) The applicable ground reactions
for nose wheel tires are as follows:
(1) The static ground reaction for the
tire corresponding to the most critical
combination of airplane weight (up to
maximum ramp weight) and center of
gravity position with a force of 1.0g
acting downward at the center of gravity. This load may not exceed the load
rating of the tire.
(2) The ground reaction of the tire
corresponding to the most critical
combination of airplane weight (up to
maximum landing weight) and center
of gravity position combined with
forces of 1.0g downward and 0.31g forward acting at the center of gravity.

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