CHECKING ALTERNATOR BELT TENSION.
If properly installed, tensioned and check periodically, the alternator drive belt will give very satisfactory service. However, an improperly tensioned belt will wear rapidly and may slip and reduce alternator output. Consequently, a belt should be checked for proper tension at the time it is installed, again after 25 hours of operation and at each 100 hour inspection thereafter.
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The torque method for checking alternator belt tension is given as follows:
1.
Apply a torque indicating wrench to the nut that attaches the pulley to the alternator and turn it in a clockwise direction. Observe the torque shown on the wrench at the instant the pulley slips.
2.
Compare the torque indicated in Step 1 with torque specified in the following chart. Adjust tension accordingly.
— Note —
The higher tension specified for a new 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 belts which have previously been used.
CHART 2403. ALTERNATOR BELT TENSION
Width of Belt Condition Torque indicated at alternator pulley
3/8 inch New 11 to 13 ft-lbs
3/8 inch Used 7 to 9 ft-lbs
BATTERY.
The battery is located in the nose of the aircraft and is accessible by opening the hinged fiberglass nose which tips forward, and then removing the battery box cover. (Refer to Figure 24-2)
SERVICE PROCEDURES.
Since the alternator and regulator are designed for use on only one polarity system, the following procedures must be observed when working on the charging circuit. Failure to observe these service procedures will result in serious damage to the electrical equipment.
1.
When installing a battery, always make sure the ground polarity of the battery and the ground polarity of the alternator are the same.
2.
When connecting a booster battery, make certain to connect the negative battery terminals together and the positive battery terminals together.
3.
When connecting a charger to the battery, connect the charger positive lead to the battery positive terminal and the charger negative lead to the battery negative terminal.
4.
Never operate the alternator on an open circuit. Make absolutely certain all connections in the circuit are secure.
5.
Do not short across or ground any of the terminals on the alternator or regulator.
6.
Do not attempt to polarize the alternator.
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Figure 24-2. Battery Box
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SERVICING BATTERY.
The battery should be checked for fluid level, but must not be filled above the baffle plates. A hydrometer check should be performed to determine the percent of charge in the battery. All connections must be clean and tight. (Refer to Chart 2404)
CHART 2404. HYDROMETER READING AND BATTERY CHARGE PERCENT
Hydrometer Reading Percent of Charge
1280 1250 1220 1190 1160 1130 or below 100 75 50 25 Very little useful capacity discharged
REMOVAL OF BATTERY.
1.
Open aircraft nose section.
2.
Disconnect the four cam locks from the battery box cover and remove the cover.
— CAUTION —
ALWAYS REMOVE THE GROUND CABLE FIRST AND INSTALL IT LAST TO PREVENT ACCIDENTAL SHORT CIRCUITING OR ARCING.
3.
Disconnect the battery cables.
4.
Lift the battery from the box.
INSTALLATION OF BATTERY.
1.
Ascertain that both the battery and battery box are clean and free from any acid.
2.
Position the battery in the box with the positive terminal closest to the positive cable.
3.
Connect the positive lead (PIC) to the positive battery terminal and secure.
4.
Connect the ground cable to the negative battery terminal and secure.
5.
Reinstall the battery box cover and secure with four cam locks; then close nose section.
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TESTING BATTERY.
The specific gravity check method is listed in Chart 2404. If the alternator output is known to be correct. the question of battery capability can be more accurately determined with a load type tester.
CHARGING BATTERY.
If the battery is not up to normal charge, remove it from the airplane and charge, starting with a charging rate of 4 amps and finishing with 2 amps. A fast charge is not recommended.
BATTERY BOX DESCRIPTION.
The box is made of thermoplastic with a vent and drain system. The vent allows fresh air to enter the box and draw off fumes that may accumulate due to the charging process of the battery. The drain is capped at the bottom of the fuselage and should be opened occasionally to drain any accumulation of liquid or during cleaning of the box.
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