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14 CFR Ch. I (1–1–14 Edition)
§ 23.681
(1) Give unmistakable warning to the
pilot when lock is engaged; or
(2) Automatically disengage the de-
vice when the pilot operates the pri-
mary flight controls in a normal man-
ner.
(b) The device must be installed to
limit the operation of the airplane so
that, when the device is engaged, the
pilot receives unmistakable warning at
the start of the takeoff.
(c) The device must have a means to
preclude the possibility of it becoming
inadvertently engaged in flight.
[Doc. No. 26269, 58 FR 42164, Aug. 6, 1993]
§ 23.681
Limit load static tests.
(a) Compliance with the limit load
requirements of this part must be
shown by tests in which—
(1) The direction of the test loads
produces the most severe loading in the
control system; and
(2) Each fitting, pulley, and bracket
used in attaching the system to the
main structure is included.
(b) Compliance must be shown (by
analyses or individual load tests) with
the special factor requirements for
control system joints subject to angu-
lar motion.
§ 23.683
Operation tests.
(a) It must be shown by operation
tests that, when the controls are oper-
ated from the pilot compartment with
the system loaded as prescribed in
paragraph (b) of this section, the sys-
tem is free from—
(1) Jamming;
(2) Excessive friction; and
(3) Excessive deflection.
(b) The prescribed test loads are—
(1) For the entire system, loads cor-
responding to the limit airloads on the
appropriate surface, or the limit pilot
forces in § 23.397(b), whichever are less;
and
(2) For secondary controls, loads not
less than those corresponding to the
maximum pilot effort established
under § 23.405.
[Doc. No. 4080, 29 FR 17955, Dec. 18, 1964, as
amended by Amdt. 23–7, 34 FR 13091, Aug. 13,
1969]
§ 23.685
Control system details.
(a) Each detail of each control sys-
tem must be designed and installed to
prevent jamming, chafing, and inter-
ference from cargo, passengers, loose
objects, or the freezing of moisture.
(b) There must be means in the cock-
pit to prevent the entry of foreign ob-
jects into places where they would jam
the system.
(c) There must be means to prevent
the slapping of cables or tubes against
other parts.
(d) Each element of the flight control
system must have design features, or
must be distinctively and permanently
marked, to minimize the possibility of
incorrect assembly that could result in
malfunctioning of the control system.
[Doc. No. 4080, 29 FR 17955, Dec. 18, 1964, as
amended by Amdt. 23–17, 41 FR 55464, Dec. 20,
1976]
§ 23.687
Spring devices.
The reliability of any spring device
used in the control system must be es-
tablished by tests simulating service
conditions unless failure of the spring
will not cause flutter or unsafe flight
characteristics.
§ 23.689
Cable systems.
(a) Each cable, cable fitting, turn-
buckle, splice, and pulley used must
meet approved specifications. In addi-
tion—
(1) No cable smaller than
1
⁄
8
inch di-
ameter may be used in primary control
systems;
(2) Each cable system must be de-
signed so that there will be no haz-
ardous change in cable tension
throughout the range of travel under
operating conditions and temperature
variations; and
(3) There must be means for visual
inspection at each fairlead, pulley, ter-
minal, and turnbuckle.
(b) Each kind and size of pulley must
correspond to the cable with which it is
used. Each pulley must have closely
fitted guards to prevent the cables
from being misplaced or fouled, even
when slack. Each pulley must lie in the
plane passing through the cable so that
the cable does not rub against the pul-
ley flange.
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