CS-VLA 729  Landing gear extension and retraction system

ED Decision 2003/18/RM

(a)                            General. For aeroplanes with retractable landing gear, the following apply:

(1)                            Each landing gear retracting mechanism and its supporting structure must be designed for maximum flight load factors with the gear retracted 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 V_S1 with flaps retracted, and for any load factor up to those specified in CS-VLA 345 for the flaps-extended condition.

(2)                            The landing gear and retracting mechanism, including the wheel well doors, must withstand flight loads, including loads resulting from all yawing conditions specified in CS-VLA 351, with the landing gear extended at any speed up to at least 1.6 V_S1 with the flaps retracted.

(b)                            Landing gear lock. There must be positive means to keep the landing gear extended.

(c)                            Emergency operation. For a landplane 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 system; 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 functioning of the retracting mechanism must be shown by operation tests up to V_LO.

(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 the gear is secured in the extended (or retracted) position. If switches are used, they must be located and coupled-to the landing gear mechanical system in a manner that prevents an erroneous indication of either ‘down and locked’ if the landing gear is not in the 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.

(f)                             Landing gear warning. For landplanes, the following aural or equally effective landing gear warning devices must be provided:

(1)                            A device that functions continuously when the throttle is closed if the landing gear is not fully extended and locked. A throttle stop may not be used in place of an aural device.

(2)                            A device that functions continuously when the wing flaps are extended to or beyond the approach flap position, using a normal landing procedure, if the landing gear is not fully extended and locked. The flap position sensing unit may be installed at any suitable location. The system for this device may use any part of the system (including the aural warning device) for the device required in subparagraph (f)(1) of this paragraph.