Sec. 25.689 - Cable systems.
(a) Each cable, cable fitting,
turnbuckle, splice, and pulley must be approved. In addition --
(1) No cable smaller than
1/8 inch in diameter may be used in the aileron, elevator, or rudder
(2) Each cable system must be designed
so that there will be no hazardous change in cable tension throughout the
range of travel under operating conditions and temperature variations.
(b) Each kind and size of pulley must
correspond to the cable with which it is used. Pulleys and sprockets must
have closely fitted guards to prevent the cables and chains from being
displaced or fouled. Each pulley must lie in the plane passing through the
cable so that the cable does not rub against the pulley flange.
(c) Fairleads must be installed so that
they do not cause a change in cable direction of more than three degrees.
(d) Clevis pins subject to load or
motion and retained only by cotter pins may not be used in the control
(e) Turnbuckles must be attached to
parts having angular motion in a manner that will positively prevent
binding throughout the range of travel.
(f) There must be provisions for visual
inspection of fairleads, pulleys, terminals, and turnbuckles.