Piper Arrow IV, Maintenance Manual

Page: 217 / 752

OVERHAUL OF ALTERNATOR.
When repairing the alternator, complete disassembly may not be required. In some cases it will only be
necessary to perform those operations which are required to effect the repair. However, in this section, the
complete overhaul is covered step-by-step to provide detailed information on each operation. In actual service
practice, these operations may be used as required.
DISASSEMBLY OF ALTERNATOR.
1. Remove the two Number 10-24 screws holding the brush holder assembly in the slip ring end head.
Remove the brush and holder assembly from the end head.
2. Remove the safety wire from the through bolts.
3. On PA-28RT-201 hold the pulley with a strap wrench and remove the pulley nut. The pulley must be
removed with a puller. Remove the fan, woodruff key and spacer from the shaft.
4. Remove the four through bolts and tap the drive end head lightly to separate the drive end head and
rotor, as a unit, from the stator and slip ring end head.
5. Remove the nuts, lockwashers, flat washers and insulators from the output and auxiliary terminal
studs. Note carefully the correct assembly of the insulator washers and bushings. Using the special tools shown
in Figure 24-30, support the end head and press out the three negative rectifiers. The end head can now be
separated from the stator assembly.
6. To remove the slip ring end bearing and grease seal, it will be necessary to have a hook type or impact
type bearing puller as shown in Figure 24-29. Do not remove the bearing unless replacement is necessary.
—NOTE—
The inner race of the slip ring end bearing is pressed onto the
rotor shaft. When bearing replacement is necessary, always
replace the complete bearing assembly, including the inner race.
7. On PA-28RT-201 models to remove the drive end head from the rotor shaft, use a puller that grips on
the bearing retainer plate as shown in Figure 24-31. Do not attempt to remove by supporting the end head and
pressing on the shaft, as this may result in distortion of the end head of stripping of the retainer plate screws.
Remove the three retainer plate screws and press the bearing out of the end head. (Refer to Figure 24-32.) On
PA-28RT-201T models support the drive end head and carefully press out the rotor assembly. Remove the three
retainer plate screws and press the bearing from the end head. (Refer to Figure 24-32.)
INSPECTION AND TESTING OF COMPONENTS.
Upon completion of the disassembly, all parts should be cleaned and visually inspected for cracks, wear or
distortion and any signs of overheating or mechanical interference.
1. Rotor: The rotor should be tested for grounded or shorted windings. The ground test can be made with
test probes, connected in series with a 110-volt test lamp, an ohmmeter or any type of continuity tester. (Refer
to Figure 24-33.) There must not be any continuity between the slip rings and the rotor shaft or poles. To test
for shorted turns in the rotor windings, connect a voltmeter, ammeter and rheostat as shown in Figure 24-34, or
use an ohmmeter. Rotor current draw and resistance are listed in the Alternator Service Test Specifications
paragraph. Excessive current draw or a low ohmmeter reading indicates shorted windings. No current draw or
an infinite ohmmeter reading would indicate an open winding.
24-33-06
EFFECTIVITY: Page 24-30
PRESTOLITE ALTERNATOR Revised: July 13, 1983
1J1
PIPER AIRCRAFT
PA-28RT-201 / 201T
MAINTENANCE MANUAL