Piper COMANCHE PA-24-180 Service Manual page 570

e
FIGURE 9-27e. REMOVAL OF DRIVE
FIGURE 9-27f. REMOVAL OF END
END HEAD HEAD BEARING
NOTE
The inner race of the slip ring end beanng is pressed onto the
rotor shaft. When bearing replacement is necessary, always re-
place the complete bearng assembly, including the inner race.
f. To remove the drive end head from the rotor shaft, use a puller that grips on the bearing
retainer plate as shown in Figure 9-27e. 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 or stripping of the
retainer plate screws. Remove the three retainer plate screws and press the bearing out of the
end head. (Refer to Figure 9-27f.)
9-61g. Inspectlon And Testing Of Components. Upon completion of the disassembly, all partns
should be cleaned and visually inspected for cracks, wear or distortion and any signs of over-
heating or mechanical interference.
a. 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 110volt test lamp, an ohmmeter or any type
of continuity tester. (Refer to Figure 9-27g.) There must not be any continuity between the slip
rings and the rotor shaft or poles. To test for shorted turns in the rotor winding, connect a volt-
meter, ammeter and rheostat as shown in Figure 9-2h. or use an ohmmeter. Rotor current draw
and resistance are listed in the individual specification pages. Excessive current draw or a low
ohmmeter reading indicates shorted windings. No current draw or an nfinite ohmmeter reading
would indicate an open winding.
b. Rectifier:
A diode rectifier tester will detect and pinpoint open or shorted rectifiers
without going through the operation of disconnecting the stator leads. However, if a tester is not
availlble, test probes and a No. 57 bulb, connected in series with a 12-volt battery, can be used
in the following manner. Touch one test probe to a rectifier heat sink and the other test probe to
ELECTRICAL SYSTEM
ISSUED: 8/11/72
3 B24
PIPER COMANCHE SERVICE MANUAL