Aircraft Alternator
Maintenance Manual
ES1031
24-30-01
Rev. B: 20 Apr. 2022
Page: 6-15
© 2022 - Hartzell Engine Technologies - All rights reserved
(4) Re-connect the blast air tube if required.
(5) If pulley is to be installed, torque pulley nut 55 to 65 ft-lbs (74.6 Nm to 88.1 Nm) and check pulley run
out per section 5.2.G. (Use pulley wrench to hold pulley, later units use 5/16 inch hex key to hold shaft
while applying torque to output shaft nut.)
CAUTION:
DO NOT EXCEED TENSION LIMITS. EXCESSIVE BELT TENSION CAN LEAD TO
PREMATURE WEAR AND BEARING FAILURE.
(6) Install the alternator belt and properly tension in accordance with the most current revision of the engine/
aircraft maintenance manuals and service instructions. If a max tension value is not provided by the OEM,
use applicable values found in table 6.2. A tensionometer should be used to set the specified belt tension.
(7) Unless otherwise advised by the OEM, connect the positive battery cable to the positive (POS) battery
terminal, then connect the aircraft ground cable to the negative (NEG) battery terminal.
(8) Check the alternator for security and make a running performance test per the AFM or POH and the engine/
aircraft service and maintenance manuals.
6.16 Special Conditions:
NOTE:
For engine OEM’s Special Condition “Sudden Stoppage”, refer to the latest revision of Lycoming
Engines, Inc. SB 533B or Continental Motors, Inc. SB96-11B.
A. Sudden Engine Stoppage
(gear drive):
(1) If the engine has experienced “sudden stoppage” as defined by the engine manufacturer, the alternator
may be impacted critically by this event. Although the alternator drive system is designed with an OEM
supplied elastomer drive coupling which protects the engine from seizure of the rotating components
inside the alternator, the coupling may place unknown strain on the alternator shaft from the sudden
stoppage of the engine drive train. The shaft may be weakened, cracked, or have unseen damage from
this event, setting up for a future failure under normal operating conditions if not thoroughly inspected.
(2) If “sudden stoppage” as defined by the engine manufacturer has occurred, the gear driven alternator must
be repaired, overhauled, or replaced. Refer to the appropriate engine or airframe manuals to remove the
alternator.
Item 3 must be performed on any sudden stoppage by a qualified repair or overhaul
shops.
(3) If the alternator has been involved in an accident with sudden stoppage and the alternator is to be
overhauled in lieu of replacement, it is required that a qualified technician perform a magnetic particle
inspection (ASTM E 1444) to check the condition of the rotor shaft.
B.
Sudden Engine Stoppage
(belt drive)
(1) If the aircraft engine has experienced a “sudden stoppage” as defined by the engine manufacturer,
the alternator may be impacted critically by this event. Although a belt driven alternator is protected
somewhat by the ability of the belt to slip or come off the pulley, the sudden stoppage may case the
seizure of the rotating components inside the alternator. The sudden stop may bend the pulley, damage
the bearings, or shift close tolerance parts inside the alternator allowing contact when rotating.
