Aircraft Alternator
Maintenance Manual
24-30-01
ES1031
Page: 6-8 Rev.
B: 20 Apr. 2022
© 2022 - Hartzell Engine Technologies - All rights reserved
6.8 Brush Removal
and Installation
NOTE:
Brushes must be replaced in pairs. If replacing brushes only, order two (2) each, HET P/N ALE-13A
brushes through an authorized HET distributor. HET recommends replacing the brush holder ass’y HET
P/N ALU-3045BS or ALE-3045BS as applicable. These include new brushes pre-installed. Refer to
Materials section 6.11.
A. Removal:
(1) Make sure aircraft battery and external power source has been disconnected.
(2) If necessary for access to the brush holder screws, remove the clamp from the air duct attached to the
alternator blast tube and disconnect the air duct.
(3) Disconnect the two top terminal nuts for F1/F2 while holding the bottom nut. Temporarily insulate the
terminals to prevent possible sparking. Refer to Figure 6.4a. Please note, some alternator models may
have an internal grounding path for the field and will not have an F2 terminal.
(4) Remove the two screws that hold the brush holder ass’y in the slip ring end housing (SRE).
Refer to
Figure 6.3a.
(5) Slowly remove the brush holder ass’y from the SRE taking care not to drop the brushes into the
alternator (brushes are spring loaded).
If checking brushes only, be sure to mark and note the position
and orientation of each brush. Discard the brushes if replacing.
(6) If both brushes are not present upon removal of the brush holder, the missing brush must be located and
recovered from the alternator before proceeding.
B. Installation:
Prepare to install brush holder into the alternator.
(1) Install a new set of brushes, HET P/N ALE-13A into the brush holder.
Place each new brush into the
brush holder. Brushes must be oriented such that the axis of the curvature of the brush face is parallel
with axis of F1/F2 terminals. Refer to Fig. 6.3c. If checking brushes only, be sure to place in the same
position and orientation as removed.
(2) Install a two inch stiff 22 gage insulated wire into the hole provided in the side of the brush holder while
pushing in each brush with a soft tool like a small wood or nylon dowel. The wire will retain the brushes
for installation of the holder. Refer to Fig. 6.3d.
(3) Install the brush holder ass’y with the insulated brush retaining wire in place. Install the two
brush
holder
screws. Refer to Fig. 6.3b.
(4) Torque the brush holder screws to 11-14 in-lbs
(14.91 to 18.99 Nm)
. Refer to Fig. 6.3a.
(5) Spin the shaft several rotations to check for interference between the brush holder and rotor.
(6) Remove insulated brush retaining wire from brush holder ass’y. Rotate shaft in running direction and
listen for smooth operation. Refer to Figure 6.3d.
(7) Torque first nut, F1 & F2 as required, to 12 -15 in-lbs. Connect field terminals from aircraft harness.
Install terminal washers and nuts. Torque second nut to 6 -8 in-lbs.
(8) Restore aircraft battery and/or other power source which has been disconnected.
6.9 Through Bolts
The alternator through bolts are designed to retain proper torque for the life of the alternator. Occasionally over
time, vibration may loosen the through bolts. This may be noticed by broken or loose safety wire or cable and
may appear as a blackened area at the through bolt head or threads. If loose, the following procedures apply:
