Piper COMANCHE PA-24-180 Service Manual page 555

PIPER COMANCHE SERVICE MANUAL
a. When installing a battery, always make absolutely sure the
ground polarity of the battery and the ground polarity of the alter-
nator are the same.
b. When connecting a booster battery, make certain to connect the
negative battery terminals together and the positive battery ter-
mminals together.
c. When connecting a charger to the battery, connect the charger
positive lead to the battery positive terminal and the charger nega-
tive lead to the battery negative terminal.
d. Never operate the alternator on open circuit. Make absolutely
certain all connections in the circuit ae secure.
e. Do not short across or ground any of the terminals on the alter-
nator or regulator.
L Do not attempt to polarize the alternator.
9-47. Inspection. Even though the alternator is constructed to give long periods of trouble-free
service, a regular inspection procedure should be followed to obtain the maximum life from the
alternator.
The frequency of inspection is determined largely by the type of operating conditions.
High speed operation, high temperatures, and dust and dirt all increase the wear of brushes, slip
rngs and bearings.
At regular intervals, inspect the terminals for corrosion and loose connections, and the
wiring for frayed insulation. Check the mounting bolts for tightness, and the belt for alignment.
propertension and wear. Belt tension should be adjustedin accordance with engine manufacturer's
recommendations. When tightening belt tension, apply pressure against the stator laminations be-
tween the end frames, and not against either end frame.
Noise from an alternator may be caused by worn or dity bearings, Loose mounting bolts, a
loose drive pulley, a defective diode, or a defective stator.
9-48. Disassembly. After extended periods of operation, or at time of engine overhaul, the alter-
nator may be removed from the aircraft for a thorough inspection and cleaning of all parts. The
alternator consists of four main components - the two end frames, the stator and the rotor.
To disassemble the alternator, take out the four thru-bolts, and separate the drive end
frame and rotor assembly from the stator assembly by prying apart with a screwdriver at the stator
slot. A mark will help locate the parts in the same position during assembly. The fit between
stator and frame is not tight, and the two can be separated easily. Note that the separation is to
be made between the stator frame and drive end frame. After disassembly, place a piece of tape
over the slip ring end frame bearing to prevent entry of dirt and other foreign material, and also
place a piece of tape over the shaft on the slip ring end. If brushes are to be re-used, clean with
a soft dry cloth.
CAUTION
Use pressure sensitive tape and not friction tape which would leave
a gummy deposit on the shaft.
ELECTRICAL SYSTEM
ISSUED: 8/18/72
3 B