Filter Element Replacement; Hydraulic Pump Operational Check; Procedure After Engine-Driven Hydraulic Pump Failure; Removal Of Hydraulic Pump - Piper Navajo Chieftain PA-31-350 Service Manual

NAVAJO CHIEFTAIN SERVICE MANUAL
6-148. REPLACEMENT OF FILTER ELEMENT. (Refer to Figure 6-27.)
a.
Remove the lower engine cowl.
b.
Cut safety wire, unscrew bowl and remove filter element.
c.
Clean filter bowl with a suitable cleaning solvent and dry.
d.
Replace filter element and "O" ring on bowl.
e.
Half fill filter bowl to minimize trapped air in the hydraulic system and replace bowl.
f.
Safety filter bowl with MS20995C20 safety wire and replace cowl
g.
After engine has been operated, check for leaks.
6-149. HYDRAULIC PUMP.
6-150. HYDRAULIC PUMP OPERATIONAL CHECK. To determine the operable condition of each
hydraulic pump, the following check may be conducted:
a.
Start one engine and allow it to warm up.
b.
With the engine operating at 1200 RPM, move the gear selector handle to the gear down position.
The one pump should build up pressure within the hydraulic system and return the selector handle to
neutral position within three to nine seconds. Again select the down position and check the handle return
time.
c.
Shutdown the engine and repeat the preceding steps for the other engine.
d.
Should it be found that the selector handle will not return to neutral during the operational
check for one pump, but will return within the required time with the check of the other, then it can be
assumed that the pump is at fault and it should be removed to determine the cause of malfunction.
6-151. PROCEDURE AFTER ENGINE-DRIVEN HYDRAULIC PUMP FAILURE. Should a pump
breakage occur, there may be metal particles in the hydraulic system. To rectify this condition the
hydraulic system should be flushed. Proceed with the following steps:
a.
Replace the defective engine-driven hydraulic pump and prime it in accordance with Paragraph
6-157. Do not connect the pump to the rest of the hydraulic system until the system has been flushed.
b.
Proceed to flush the system in accordance with Paragraph 6-4.
c.
Remove the filter elements and check for metal particles. If metal particles are evident in the
filter. clean the filter bowl with dry cleaning solvent and dry with compressed air. Install new filter
elements in accordance with Paragraph 6-148.
6-152. REMOVAL OF HYDRAULIC PUMP.
a.
Remove left or right engine cowls, as required by skin fasteners and separate the two halves.
b.
Place a drip pan under the engine to catch spillage.
c.
Disconnect the two hydraulic hoses from the end of the pump.
d.
Disconnect drain hose from bottom of pump.
e.
Remove the four nuts, lockwashers, and flat washers from the base of the pump.
f.
Remove the pump from the engine housing.
g.
Upon removal of the pump from its drive gear, remove the destroy or discard and gasket from the
pump mounting face. The gasket and all seal rings should be replaced with new parts upon reassembly.
Never reinstall an old gasket or seal ring.
Reissued: 9/23/80
HYDRAULIC SYSTEM
2D4