The landing gear is a retractable, tricycle type with a steerable nose wheel and two main wheels. Shock absorption is provided by the tubular spring-steel main landing gear struts and the air! oil nose gear shock strut. Each main gear wheel is equipped with a hydraulically actuated single- disc brake on the inboard side of each wheel.
The landing gear extension, retraction, and main gear down lock release operation is accomplished by hydraulic actuators powered by an electrically-driven hydraulic power pack (see figure 7-7). The power pack is located aft of the firewall between the pilot's and copilot's rudder pedals. The hydraulic system fluid level may be checked by utilizing the dip stick/filler cap located on the top left side of the power pack adjacent to the motor mounting flange. The system should be checked at 25-hour inter vals. If the fluid level is at or below the ADD line on the dipstick, hydraulic fluid (MIL-FI-5606) should be added to bring the level to the top of the dipstick/filler cap opening. A normal operating pressure of 1000 PSI to 1500 PSI is automatically maintained in the landing gear system, and is sufficient to provide a positive up pressure on the landing gear. The nose gear and main gear incorporate positive mechanical down locks. Also, the nose gear has mechanically-actuated wheel well doors. The doors open when the nose gear extends, and close when it retracts.
Power pack operation is started
and stopped by a pressure switch, and hydraulic pressure is directed by the
landing gear lever. Two position indicator lights are provided to show landing
gear position. The landing gear system is also equipped with a nose gear safety
(squat) switch, an emergency extension hand pump, and a gear-up warning
LANDING GEAR LEVER
The landing gear lever is
located on the switch and control panel to the right of the electrical switches.
The lever has two positions, labeled GEAR UP and GEAR DOWN, which give a
mechanical indication of the gear position selected. From either position, the
lever must be pulled out to clear a detent before it can be repositioned;
operation of the landing gear system will not begin until the lever has been
repositioned. After the lever has been repositioned, it directs hydraulic
pressure within the system to actuate the gear to the selected
LANDING GEAR POSITION INDICATOR LIGHTS
Two position indicator lights,
adjacent to the landing gear control lever, indicate that the gear is either up
or down and locked. Both the gear- up (amber) and gear-down (green) lights are
the press-to-test type, incorporating dimming shutters for night operation. If
an indicator light bulb should burn out, it can be replaced in flight with the
bulb from the remaining indicator light.
LANDING GEAR OPERATION
To retract or extend the landing gear, pull out on the gear lever and move it to the desired position. After the lever is positioned, the power pack will create pressure in the system and actuate the landing gear to the selected position. During a normal cycle, the gear retracts fully or extends and locks, limit switches close (GEAR DOWN cycle only), and the indicator light comes on (amber for up and green for down) indicating completion of the cycle. After indicator light illumination, during a GEAR DOWN cycle, the power pack will continue to n.m until the fluid pressure reaches 1500 PSI, opens the pressure switch, and turns the power pack off. Whenever fluid pressure in the system drops below 1000 PSI, the pressure switch will close and start power pack operation, except when the nose gear safety (squat) switch is open.
The safety (squat) switch,
actuated by the nose gear, electrically prevents inadvertent retraction whenever
the nose gear strut is com pressed by the weight of the airplane. When the nose
gear is lifted off the runway during takeoff, the squat switch will close, which
may cause the power pack to operate for ito 2 seconds and return system pressure
to 1500 PSI in the event pressure has dropped below 1000 PSI. A "pull-off" type
circuit breaker is also provided in the system as a maintenance safety feature.
With the circuit breaker pulled out, landing gear operation by the gear pump
motor is prevented. After maintenance is completed, and prior to flight, the
circuit breaker should be pushed back in.
EMERGENCY HAND PUMP
A hand-operated hydraulic pump,
located between the front seats, is provided for manual extension of the landing
gear in the event of a hydraulic system failure. The landing gear cannot be
retracted with the hand pump. To utilize the pump, extend the handle forward,
and pump vertically. For complete emergency procedures, refer to Section
LANDING GEAR WARNING SYSTEM
The airplane is equipped with a landing gear warning system designed to help prevent the pilot from inadvertently making a wheels-up landing. The system consists of a throttle actuated switch which is electrically connected to a dual warning unit. The warning unit is connected to the airplane speaker.
When the throttle is retarded
below approximately 12 inches of manifold pressure at low altitude (master switch
on), the throttle linkage will actuate a switch which is electrically connected
to the gear warning portion of a dual warning unit. If the landing gear is retracted
(or not down and locked), an intermittent tone will be heard on the airplane
speaker. An interconnect switch in the wing flap system also sounds the horn
when the wing flaps are extended beyond 20 deg with the landing gear retracted.