Starting Motor Assembly; Bench Tests; Starting Motor Control Circuit Check - Piper PA-44-180 SEMINOLE Maintenance Manual

ASSEMBLY OF STARTING MOTOR.
1. When assembling the starting motor, always use an arbor press and the proper bearing arbor for installing
graphitized bronze and roller bearings. The Bendix shaft should have a thin film of Lubriplate #777 or
equivalent on the Bendix portion of the shaft. End play should be .005 to .050 of an inch.
2. New brushes should be properly seated when installing by wrapping a strip of 00 sandpaper around the
commutator, with sanding side out, 1 1/4 to 1 1/2 times maximum. Drop brushes on sandpaper covered
commutator and turn the armature slowly in the direction of rotation. Dust should be blown out of the
motor after sanding.
The spring tension is 32 to 40 ounces with new brushes This tension is mea~red with a
spring scale hooked under the brush spring near the brush and the reading is taken at
right angles to the line of force exerted by the brush spring.
3. Check the position of the pinion to be sure the unit will mesh properly with the flywheel ring gear. See
Chart 8002 for specifications.

BENCH TESTS.

1. After the starting motor is reassembled, it should be tested to see that no load current at a certain voltage is
within specification as given in Chart 8002. To make this test, connect as shown in Figure 80-5. If current
is too high, check the bearing alignment and end play to make sure there is no binding or interference. Two
or three sharp raps on the frame with a rawhide hammer will often help to align the bearings and free the
armature.
2. If no difficulty is indicated in the above test, a stall torque test may be made to see if the starting motor is
producing its rated cranking power. Make test connections as shown in Figure 80-6.
3. If torque and current are not within specifications, check the seating of the brushes and internal connections
for high resistance. If these checks are made and found to be in good order, replace frame and field
assembly and retest starter.
STARTING MOTOR CONTROL CIRCUIT.
1. Inspect the control circuit wiring between the battery, solenoid and manual starting switch for breaks, poor
connections and faulty insulation. Tighten all ground connections and make sure solenoid is firmly
mounted and makes a good ground connection.
2. Check the voltage loss across the switch contacts during normal starting. If loss is in excess of 0.2 volts per
100 amps, the solenoid should be replaced.
3. If solenoid fails to operate when the manual starting switch is turned on, or if it fails to release when the
manual starting switch is released, it should be replaced.
PIPER AIRCRAFT
PA - 4 4 - 1 8 0 / 1 8 0 T
AIRPLANE MAINTENANCE MANUAL
— Note —
3I20
8 0 - 1 0 - 1 3
Page 80-08
Revised: May 15, 1989