CHAPTER 24
PAGE 15
PAGE DATE: 21. March 2014
MAINTENANCE MANUAL EXTRA 300LT
Use the following simple method (Torque Method) to check
proper tension of the drive belt. This method of checking
drive belt tension consists of measuring the torque required
to slip the drive belt at the small pulley and is accomplished
as follows:
1 Secure the propeller to prevent rotation of the engine.
2 Apply a torque indicating wrench to the nut that attaches the
pulley to the alternator and turn it in a clockwise rotation.
Observe the torque shown on the wrench at the instant the
pulley slips.
3 Check torque indicated in step 2 with the torque specified
in the following.
N O T E The higher drive belt tension specified in the following
for the new drive belt is to compensate for the initial
stretch that takes place as soon as it is operated. These
higher tension values should not be applied to drive
belts that have been used previously.
Condition: Torque indicated at alternator pulley
New drive belt: 15 to 18 Nm (10 to 13 ft.lbs.)
Used drive belt: 10 to 12 Nm (7 to 9 ft.lbs.)
4 Adjust belt tension accordingly.
Tension Adjustment
1a (Bosch) Remove cotter pins at castle nuts (2 & 3, Figure 1)
and safety wire at bolt (1).
1b (Prestolite) Remove cotter pin at castle nut (7, Figure 1)
and safety wires at bolts (4 & 5).
1c (Plane Power) Remove safety wires at bolts (8 & 9, Figure
3).
2a (Bosch) Slightly loosen bolt (1) and castle nuts at bolts
(2 & 3) to release drive belt tension.
2b (Prestolite) Slightly loosen bolts (4 & 5) and castle nut (7)
to release drive belt tension.
2c (Plane Power) Slightly loosen bolts (8 & 9) and stop nut at
bolt (10) to release drive belt tension.
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