Code of Federal Regulations - Title 14

246

14 CFR Ch. I (1–1–14 Edition)

§ 23.726

=the load factor developed in the drop test

(that is, the acceleration (

dv/dt) in gs re-

corded in the drop test) plus 1.0; and

W, and L are the same as in the drop test

computation.

(f) The value of

n determined in ac-

cordance with paragraph (e) may not
be more than the limit inertia load fac-
tor used in the landing conditions in
§ 23.473.

[Doc. No. 4080, 29 FR 17955, Dec. 18, 1964, as
amended by Amdt. 23–7, 34 FR 13091, Aug. 13,
1969; Amdt. 23–48, 61 FR 5148, Feb. 9, 1996]

§ 23.726

Ground load dynamic tests.

(a) If compliance with the ground

load requirements of §§ 23.479 through
23.483 is shown dynamically by drop
test, one drop test must be conducted
that meets § 23.725 except that the drop
height must be—

(1) 2.25 times the drop height pre-

scribed in § 23.725(a); or

(2) Sufficient to develop 1.5 times the

limit load factor.

(b) The critical landing condition for

each of the design conditions specified
in §§ 23.479 through 23.483 must be used
for proof of strength.

[Amdt. 23–7, 34 FR 13091, Aug. 13, 1969]

§ 23.727

Reserve energy absorption

drop test.

(a) If compliance with the reserve en-

ergy absorption requirement in
§ 23.723(b) is shown by free drop tests,
the drop height may not be less than
1.44 times that specified in § 23.725.

(b) If the effect of wing lift is pro-

vided for, the units must be dropped
with an effective mass equal to

Wh/

(h+d), when the symbols and other de-
tails are the same as in § 23.725.

[Doc. No. 4080, 29 FR 17955, Dec. 18, 1964, as
amended by Amdt. 23–7, 34 FR 13091, Aug. 13,
1969]

§ 23.729

Landing gear extension and

retraction system.

(a)

General. For airplanes with re-

tractable landing gear, the following
apply:

(1) Each landing gear retracting

mechanism and its supporting struc-
ture must be designed for maximum
flight load factors with the gear re-
tracted and must be designed for the
combination of friction, inertia, brake

torque, and air loads, occurring during
retraction at any airspeed up to 1.6

with flaps retracted, and for any load
factor up to those specified in § 23.345
for the flaps-extended condition.

(2) The landing gear and retracting

mechanism, including the wheel well
doors, must withstand flight loads, in-
cluding loads resulting from all yawing
conditions specified in § 23.351, with the
landing gear extended at any speed up
to at least 1.6

with the flaps re-

tracted.

(b)

Landing gear lock. There must be

positive means (other than the use of
hydraulic pressure) to keep the landing
gear extended.

(c)

Emergency operation. For a land-

plane having retractable landing gear
that cannot be extended manually,
there must be means to extend the
landing gear in the event of either—

(1) Any reasonably probable failure in

the normal landing gear operation sys-
tem; or

(2) Any reasonably probable failure in

a power source that would prevent the
operation of the normal landing gear
operation system.

(d)

Operation test. The proper func-

tioning of the retracting mechanism
must be shown by operation tests.

(e)

Position indicator. If a retractable

landing gear is used, there must be a
landing gear position indicator (as well
as necessary switches to actuate the
indicator) or other means to inform the
pilot that each gear is secured in the
extended (or retracted) position. If
switches are used, they must be located
and coupled to the landing gear me-
chanical system in a manner that pre-
vents an erroneous indication of either
‘‘down and locked’’ if each gear is not
in the fully extended position, or ‘‘up
and locked’’ if each landing gear is not
in the fully retracted position.

(f)

Landing gear warning. For land-

planes, the following aural or equally
effective landing gear warning devices
must be provided:

(1) A device that functions continu-

ously when one or more throttles are
closed beyond the power settings nor-
mally used for landing approach if the
landing gear is not fully extended and
locked. A throttle stop may not be
used in place of an aural device. If

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