Starter System Maintenance; Starting Motor Overhaul; Starting Motor Removal; Starting Motor Disassembly - Piper Navajo Chieftain PA-31-350 Service Manual

NAVAJO CHIEFTAIN SERVICE MANUAL
When the engine reaches a predetermined speed, centrifugal action forces the detent pin out of the
notch in the screw shaft and allows the pinion to demesh from the flywheel.
11-33. MAINTENANCE.
The starting circuit should be inspected at each 100-hour inspection interval or
sooner. which should be determined by the amount of service and the conditions under which
the aircraft is
operated.
NOTE
Since proper operation of the starter system depends on an
appropriate amount of power from the battery. it is recommended
that a thorough inspection of the battery and its compartment be
accomplished at each 50-hour inspection or every 30 days. Refer to
paragraph 11-51 and 11-51a for further information.
a.
The primary considerations to keep in mind when working with the starter system are to insure that
all electrical terminals are clean and tight and that the wire insulation is sound. A voltage loss test should
be
made to locate any high-resistance connections that would affect starting motor efficiency. This test is made
with a low-reading voltmeter while cranking the engine or at approximately 100 amperes. and the following
limits should be used:
1.
Voltage loss from insulated battery post to starting motor terminal - 0.3 volt maximum.
2.
Voltage loss from battery ground post to starter frame - 0.1 volt maximum.
NOTE
If voltage loss is greater than the limits outlined in steps I and 2.
additional tests should be made over each part of the circuit to
locate the high-resistance connections.
c.
No lubrication is required on the starting motor except at the time of overhaul. Then lubricate
the entire shaft under Bendix Drive. fill grooves in armature shaft at drive end and pack
gear box with 1.3
to 2.0 ounces of Lithium Soap Base Grease #1925 Molytex "O" or equivalent.
d.
The starting motor should be operated for a few seconds with engine ignition off to make
sure
that the pinion engages properly and that it turns freely without binding or excessive noise.
Then the engine
should be started two or three times to see that the pinion disengages properly when the engine
is turned off.
11-34. OVERHAUL.
If during the above inspection any indication of starting motor difficulty is noted.
the starting motor should be removed from the engine for cleaning and repair.
11-35. REMOVAL. To remove the starting motor from the engine, first disconnect the ground
cable from
the battery post to prevent short circuiting. Disconnect the lead from the starting motor
terminal. then take
out the mounting bolts. The motor can then be lifted off and taken to the bench for overhaul.
11-36. DISASSEMBLY.
a.
Remove the frame screws from the commutator end head and pull end head and armature
from
frame. Lift the brushes and lock in elevated position with brush springs. Use a puller to remove
the end head
from the armature. Use a special bearing puller to remove the sealed ball bearing from the
armature shaft.
b.
Remove the frame screws that secure the gear housing to the frame. Remove bolts and nuts holding
the gear housing to the pinion housing and separate the two units. Pull Bendix shaft from pinion
housing. Do
not lose the steel spacer that is located on the pinion end of the shaft. Remove reduction
gear. woodruff key
and steel spacer from shaft.
c.
Turn the Bendix pinion until it locks in the extended position. Locate "spirol" pin
and use a
punch to remove. Slide drive assembly off the shaft. Do not attempt to disassemble the
drive and do not
dip it in cleaning solvent.
ELECTRICAL
SYSTEM
ELECTRICAL SYSTEM
Revised: 10/5/83 3D13