Piper Navajo PA-31 Service Manual page 375

PIPER NAVAJO SERVICE MANUAL
6-158. CLEANING, INSPECTION AND REPAIR OF HYDRAULIC PUMP.
a.
Immerse and wash all metallic parts in trichlorethylene (Military Specification MIL-T-7003) or
some equivalent commercial cleaning solvent. Clean all openings and passages with a fine fiber brush, or
equivalent, dipped in solvent. Do not scrub any surface with a tool that will scratch surface.
WARNING
Wear goggles, rubber gloves and provide adequate ventilation when
using trichlorethylene or cleaning solvents. Repeated contact of
solvent with skin may produce irritation. If vapors are inhaled,
serious damage may result.
b.
Dry all parts thoroughly with a clean, lint-free cloth or with dry, filtered compressed air at 20 psi
maximum. Blow out all parts, bores, and passages with compressed air.
c. Under strong light and preferably under magnification, inspect all parts for scoring, nicks,
scratches, pitting, corrosion, cracks and excessive wear. Inspect all threaded surfaces for chipping and
crossed or stripped threads. Inspect parts for conformance to information given in Table VI-III. The table
gives the items which should be inspected and the corrective action necessary when the pump parts do not
pass this inspection.
NOTE
Although the pump may still operate under conditions where
some of the parts exceed the wear limits, it will probably be found
that the pump is not producing its rated capacity and therefore,
the system may not be doing an adequate job. Therefore, it is
necessary to repair or replace any parts that are not within the
stated limits.
6-159. ASSEMBLY OF HYDRAULIC PUMP. (Refer to Figure 6-34.) The seal and seal rings should be
soaked in the hydraulic (MIL-H-5606) fluid for two hours minimum time before installation.
a. Replace drive shaft seal (4 or 5) into drive side seal bore. Be sure to install drive shaft seal, "back
to back," as noted during disassembly.
b. Replace retainer ring (3) into drive side seal bore.
c. Install new "O" ring seal (9) on drive side.
d.
Mate centerplate assembly (10) with drive side assembly (7) and align dowel pins.
e. Install drive shaft (1) from engine side of drive side assembly.
f.
Install secondary shaft (17) into centerplate. Install drive and secondary gears (19 and 18) onto
drive and secondary shafts (1 and 17). Be sure the drive pin counter bore on the drive gear faces the pump
rear side. Install drive pins.
g. Install the four studs (12) and new "O" ring seal (15) on the rear side assembly (13).
h. Lightly oil gear teeth with hydraulic fluid before completing assembly.
i. Mate the rear side assembly (13) with the centerplate (10), using caution to align the drive and
secondary shafts with the respective holes in the rear side assembly.
j.
Replace the four locknuts (8) on the studs (14) extending out of the drive side flange that mates
with the centerplate.
k. Replace the four socket head cap screws (12) that secure the rear side, centerplate and drive side
assemblies together. Torque the socket head cap screws and locknut to 60 inch-pounds.
1.
When the pump is assembled, turn drive shaft by hand to make sure the pump turns freely. If
there is any sticking or binding at all, disassemble pump and determine the trouble. Do not apply power to
the pump until it turns freely by hand.
Reissued: 10/12/79
HYDRAULIC SYSTEM
2D21