Hydraulic Operational Checks; Hydraulic Test Unit; Indroduction (Piper Test Unit); Cycling Landing Gear - Piper Navajo Chieftain PA-31-350 Service Manual

NAVAJO CHIEFTAIN SERVICE MANUAL
6-5. HYDRAULIC OPERATIONAL CHECKS.
6-6. HYDRAULIC TEST UNIT (PIPER NO. 753 080).
6-7. INTRODUCTION (PIPER TEST UNIT). This test unit offers a means of checking hydraulic systems.
hydraulic power packs and related components. Examples are: Gear cycling operation. power pack operating
pressure. main relief valve cracking pressure. thermal relief vent valve cracking pressure. landing gear detent
release pressure. etc.
This unit consists of an electric motordriven hydraulic pump. bypass valve. fluid reservoir. filter. pressure
gauge. hoses and adapter fittings housed in a metal cabinet mounted on casters.
6-8. CONNECTING HYDRAULIC TEST UNIT.
a. Remove the access panel on the right side of the nose section.
h. If the system requires filling only. remove the protective cap from the suction. fill and drain valve
and connect the pressure hose from the test unit. Open the valve on the suction port by placing the control
lever in the up position. proceed to fill the system per instructions with test unit. Observe the sight gauge on
O7one power pack only to determine when the reservoir is full or stop filling operation when fluid is seen
draining from the overflow.
c. If the system must he operated during various ground checks. overhaul. or inspection of its com-
ponents. remove the protective caps from both the suction and the pressure ports and connect the test unit
pressure hose to the pressure port and the test unit suction hose to the suction port. Open the valve on the
suction port and proceed to operate the test unit according to instructions furnished with it.
6-9. CYCLING LANDING GEAR.
a. Connect hydraulic test unit in accordance with paragraph 6-8 and jack the airplane as outlined in
Section II.
CAUTION
When cycling the landing gear DO NOT use the manual hand pump
located between the pilot and copilot seats for this operation.
h Set hydraulic test unit bypass valve open.
c. Start test unit pump motor.
d. Slowly close bypass valve completely.
e. Using landing gear selector handle in airplane. operate gear as desired.
NOTE
Gear cycling time can be prolonged by slowly opening the test unit
bypass valve part way. This will bleed off part of the pump flow.
I.
After completion of cycling. open the test unit bypass valve and stop the pump motor.
g. Disconnect hydraulic test unit in accordance with paragraph 6-17.
h. Ascertain that the landing gear selector handle is in the down neutral position. and that the landing
gear is down and locked.
i. Remove the airplane from jacks.
Revised:
10/5/832A HYDRAULIC SYSTEM
2A19