Cleaning, Inspection And Repair Of Power Pack; Testing Reservoir For Leakage; Disassembly Of Manifold - Piper Cheyenne IIIA Airplane Maintenance Manual

PIPER AIRCRAFT
PA-42-720 (Advanced Trainer)
MAINTENANCE MANUAL
A. Main (continued)
18. Cleaning, Inspection and Repair of Power Pack.
(a) Discard all old O-rings and gaskets.
(b) Remove line fittings caps, wash all parts in dry cleaning solvent (Federal Specification P-S-661,
or equivalent), and dry with filtered compressed air.
NOTE: During inspection and until power pack is reassembled, keep parts as clean as
possible. After cleaning parts, place on clean surface and cover with clean cloth.
(c) Inspect all parts for scratches, scores, chips, cracks, and excess wear.
(d) Use parts catalog to obtain proper replacement parts for power pack.
19. Assembly of Reservoir. (Figure 403)
(a) Lubricate O-ring (MS28775-009). Install onto top center stud.
(b) Install center stud into body (PPN 762-589).
(c) Lubricate two reservoir O-rings and install.
(d) Push reservoir into body.
(e) Drop baffle plate into reservoir. Secure by placing snap ring into center stud.
20. Testing Reservoir for Leakage. (Figure 403)
(a) Remove drain fitting. Attach test hand pump with 200 psi gauge to drain port.
(b) Remove cap from reservoir vent fitting at top of reservoir. Operate hand pump until reservoir is
completely full. (Indicated by fluid coming out of vent fitting.)
(c) Cap reservoir vent fitting.
(d) Operate test hand pump to raise pressure in reservoir until pressure gauge indicates maximum
50 psi.
(e) Check for leaks and ensure no external leakage is found.
(f) Crack vent fitting to release pressure, remove test equipment, drain reservoir and cap fittings.
(g) Install hydraulic power pack in airplane.
21. Disassembly of Manifold. (Figure 404)
(a) Unscrew door solenoid from manifold. Remove plunger return spring.
(b) Remove pin; remove plunger from spool by carefully pulling it from manifold.
(c) With hook made from a brass welding rod, withdraw transfer sleeve from manifold by inserting
hook into oil hole in transfer sleeve.
NOTE: Ensure end of hook is not over 0.06 inches long. Use hook carefully to prevent
scratching bore in manifold. The sleeve is difficult to withdraw due to O-ring friction.
(d) Remove screw, spring, and time delay plunger by inserting small wooden dowel in center of
plunger.
(e) Remove landing gear selector spool by grasping rack (teeth) end of spool and pulling it from
manifold.
NOTE: Do not bend but pull selector spool straight out. The landing gear selector spool, time
delay plunger and manifold are matched, lapped parts and must be replaced as an
assembly only.
EFFECTIVITY:
040-999
PAGE 190 29-10-00
Jan 10/90