Piper Navajo PA-31 Service Manual page 384

SECTION VII
LANDING GEAR AND BRAKE SYSTEM
7-1. DESCRIPTION. The tricycle landing gear system incorporates an air-oil type unit that is hydraulically
operated and fully retractable with the nose gear retracting aft into the nose section and the main gear
retracting inboard into the wing. Doors completely cover the gear when retracted. The nose and outboard
main gear doors operate by mechanical linkage and remain open when the gear is extended. The main gear
inboard doors operate hydraulically and are controlled by the limit switches, opening during gear extension
and closing again when the gear is fully extended. To prevent the gear from retracting while the airplane is
on the ground, an anti-retraction safety switch located on the left gear upper torque link will not allow the
gear actuator lever to move to the gear up position until the weight of the gear has allowed the strut to
extend to within one-quarter of an inch of full extension.
The nose gear is steerable through a 40 degree arc by the use of the rudder pedals. As the gear retracts,
however, the steering linkage becomes separated from the gear so that rudder pedal action with the gear
retracted is not impeded by the nose gear operation. For more information refer to Piper Service Spares
Letter No. 352 and Piper Kit - 763-981 nose gear strut assembly modification.
Located on the instrument panel, above and to the right of the gear selector control are one red and
three green indicator lights. The red light will show an indication when the gear is not locked in eigher the
up or down position. The green lights will show when each individual gear is down and locked. There is no
indication light when the gear is up and locked. The red light will also show an indication whenever the in-
board gear doors are not completely closed. When power from either or both engines is reduced below 10 to
12 inches of manifold pressure, a horn in the cockpit will sound. On serial numbered aircraft 31-855 and up,
the gear warning horn will also sound when the flap selector switch is in the down position and the gear is not
in the down and locked position regardless of the actual flap or throttle position. When the switch is in the
"OFF" or "UP" position and the gear is not down and locked, the warning horn will only sound when the
throttles are retarded. This horn will also sound whenever the gear selector handle is in the up position, while
the airplane is on the ground, and the master switch is on. The selector handle cannot be moved to the gear up
position with the airplane on the ground unless the selector mechanism is not properly adjusted or the anti-
retraction system is inoperative. Located between pilot seats, under the floor panel, is a hand pump to be used
should the primary hydraulic system fail.
The brakes are hydraulically actuated by individual master cylinders mounted on the left (optional on
the right) set of rudder pedals. A reservoir, accessible through the nose baggage compartment door, supplies
fluid to each master cylinder. From these cylinders, hydraulic fluid is routed through lines and hoses to a
parking brake valve, located on the left-aft side of the forward cabin bulkhead, through the cabin and wings
to the brake assemblies. To operate the brakes, apply toe pressure against the top of the rudder pedal. The
parking brake may be actuated by applying toe pressure and at the same time pulling out on the brake
handle. To relieve parking brake pressure, apply toe pressure on the pedals and at the same time push in on
Revised: 3/11/81
LANDING GEAR AND BRAKE SYSTEM
2E6
PIPER NAVAJO SERVICE MANUAL