shock struts are extended (normally after takeoff), or
compressed (normally after landing). The safety switch
on the right main landing gear strut deactivates the
landing gear control circuits, cabin pressurization
circuits, and the flight hour meter when the shock strut is
compressed. This switch also activates a downlock
hook, preventing the landing gear from being raised
while the aircraft is on the ground. The hook, which
unlocks automatically after takeoff, can be manually
overridden by pressing down on the red button,
placarded DN LOCK REL located adjacent to the
landing gear handle (fig. 2-6). If the override is used,
the landing gear warning horn will sound intermittently
and two red parallel-wired indicator lights located in the
landing gear control switch handle will illuminate,
provided the BATTERY switch is on. The safety switch
on the left main landing gear strut activates the left and
right engine ambient air shut-off valves when the strut is
Landing Gear Alternate Extension.
After an emergency landing gear extension
has been made, do not move any landing
gear controls, or reset any switches or
circuit breakers until the aircraft is on jacks.
The failure may have been in the gear-up
circuit which could cause the gear to retract
while the aircraft is on the ground.
If for any reason the three green GEAR
DOWN indicator lights do not illuminate
(e.g., in case of an electrical system failure),
continue pumping until sufficient resistance
is felt to ensure that the gear is down and
locked. Do not stow the hand pump handle.
Stowing the handle will release hydraulic
pressure. If the three GEAR DOWN
indicator lights are not illuminated, the
engaged and hydraulic pressure may be the
only thing holding the landing gear down.
An extension lever, placarded LANDING GEAR
ALTERNATE EXTENSION, is located on the floor
between the crew seats. A manual pumping action with
the handle lowers the landing gear. The hydraulic
pump, which is utilized to manually lower the gear is
located under the floor.
To engage the system, pull the LANDING GEAR
CONTROL circuit breaker, located on the overhead
circuit breaker panel (fig. 2-7), and ensure that the LDG
GEAR CONTR handle is in the DN position. Remove
the extension lever from the securing clip and pump the
lever up and down until the three green GEAR DOWN
indicator lights illuminate. As the handle is moved,
hydraulic fluid is drawn from the hand pump suction port
of the power pack and routed through the hand pump
pressure port to the actuators. After an alternate
extension of the landing gear, ensure that the extension
lever is in the full down position prior to stowing the
pump handle in the retaining clip. When the pump
handle is stowed, an internal relief valve is actuated to
relieve the hydraulic pressure in the pump.
After a practice alternate extension, stow the
extension handle, reset the LANDING GEAR CONTROL
circuit breaker, and retract the gear in the normal
manner with the landing gear control handle.
Tires. The aircraft is equipped with dual 22 x
6.75 x 10, 8 ply rated, tubeless rim-inflation tires on
each main gear and a 22 x 6.75 x 10, 8 ply rated,
tubeless tire on the nose wheel.
Steerable Nose Wheel. The aircraft is
maneuvered on the ground by the steerable nose wheel
system. Direct linkage from the rudder pedals (fig. 2-8)
to the nose wheel steering linkage allows the nose wheel
to be turned 12° to the left of center or 14° to the right.
When rudder pedal steering is augmented by main
wheel braking action, the nose wheel can be deflected
up to 48° either side of center. Shock loads which would
normally be transmitted to the rudder pedals are
absorbed by a spring mechanism in the steering linkage.
Retraction of the landing gear automatically centers the
nose wheel and disengages the steering linkage from
the rudder pedals.
Wheel Brake System. The main wheels are
equipped with multiple-disc hydraulic brakes, actuated
by master cylinders attached to the toe brake sections of
the rudder pedals. Brake fluid is supplied to the system
from a reservoir in the nose compartment Braking is
permitted from either set of rudder pedals. No
emergency brake system is provided. Repeated
application of brakes with insufficient cooling time
between applications will cause a loss of braking
efficiency, and may cause brake or wheel failure, tire
blowout, or destruction of wheel assembly by fire.
2-8. PARKING BRAKE.
Dual parking brake valves are installed below the
simultaneously by pressing both brake pedals to build up
pressure, then pulling out the handle placarded
PARKING BRAKE, on the pilot's subpanel (fig. 2-6).
Pulling the handle full out sets the check valves in the
system and any pressure being applied by the toe
brakes is maintained The parking brake is released
when the brake handle is pushed in. The parking brake
may be set from either cockpit position. The parking
brake shall not be set during flight.