CHECKING ALTERNATOR BELT TENSION
An improperly tensioned belt may wear rapidly or slip, reducing alternator output. Check belt for proper
tension when installed, at 25 hours of operation, and every l00 hours thereafter.
—NOTE—
For aircraft with air conditioning installed, refer to chapter 21,
for replacement and adjustment of compressor drive belt.
There are three methods of checking alternator belt tension; the first method is preferable because it is
technically simple and requires little time.
l. Torque Method: This method of checking belt tension consists of measuring torque required to
slip belt at small pulley:
a. Apply a torque indicating wrench to nut that attaches pulley to alternator and turn it in a clockwise
direction. Observe torque shown on the wrench at instant pulley slips.
b. Check torque indicated in step a. with torque specified in chart 2404. Adjust belt tension
accordingly.
CHART 2404. ALTERNATOR BELT TENSION
Torque indicated at
Width of Belt Condition alternator pulley
3/8 inch New l1 to 13 ft-lbs
3/8 inch Used 7 to 9 ft-lbs
1/2 inch New 13 to 15 ft-lbs
1/2 inch Used 9 to 11 ft-lbs
—NOTE—
The higher tension specified for a new belt is to compensate for
initial stretch that takes place as soon as it is operated. These
higher tension values should not be applied to belts which have
been used previously.
—NOTE—
Chrysler alternators do not have a nut on the shaft and therefore
cannot be checked by this method.
24 - 33 - 00
Page - 24 - 36
Reissued: August 1, 1986
1J11
PIPER AIRCRAFT
PA-28-236
MAINTENANCE MANUAL
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