Aircraft Alternator
Maintenance Manual
ES1031
24-30-01
Rev. B: 20 Apr. 2022
Page: 3-5
© 2022 - Hartzell Engine Technologies - All rights reserved
3.2 Continued
Table 3.4
Drive coupler slipping:
Inspect the condition of the drive clutch. (as applicable) This part is supplied by the
engine manufacturer. Improper tension supplied by this clutch will allow slippage during high alternator output.
Drive Belt slipping:
Inspect the condition of the pulley belt. (as applicable) The belt is supplied by the engine
manufacturer. Improper tension supplied on the belt may allow slippage during high alternator output.
Foreign object in cooling duct:
Check the duct length and the inlet of the alternator to see if debris have entered
the alternator and are rubbing internally or vibrating in the duct.
Loose rear housing or improperly installed stator:
Examine through bolts, if loose and distorted or severe
“smoking” or black areas appear at the head of the bolt, the alternator should be overhauled or replaced.
Loose mounting bolts:
Inspect mount points for damage and if found overhaul the alternator. If not, re-torque
mounting bolts per the engine or aircraft service manual.
Loose cooling duct connection:
If cooling duct is installed improperly (normally an airframe component), adjust
and tighten the mounting connection (as applicable). Check and clear any interference with the airframe structure.
Interference from airframe components or structure:
Examine the alternator and large electrical cables for
contact or chaffing on airframe structure. Check and clear any interference areas.
Shorted rectifier (magnetic noise):
Perform the tests for rectifiers as found in section 6. Disassembly may be
required to verify symptom. Replace or overhaul alternator.
Insufficient output filtering:
Check the RFI filter by performing a capacitance check. Replace RFI filter
if failed (external filter only). If an internal PCB type filter, replace or overhaul alternator if failed. In some
cases, additional RFI filters may be installed, be sure that a check is performed on each. If only one RFI filter
is installed, additional filters may be required to reduce noise.
