General Description; Power Distribution; Battery And External Power; Battery Servicing - Thrush Aircraft S2R–T660 Maintenance Manual

ELECTRICAL SYSTEM
SECTION TEN
The aircraft 24-volt DC electrical system is designed to provide the utmost in reliability. Two 24-volt
storage batteries provide electric current for engine starting and a reserve source of electrical power
in the event of generator failure. A D.C. power receptacle provides a means for connecting external
power to the aircraft electrical system. To conserve battery life, external power should always be
used for starting engines when temperature is below 40
requiring electrical power. A generator installed on the engine supplies the primary source of
electrical power to the main bus. A voltage regulator protects the electrical system, reverse current
relay and circuit breakers. If generator output voltage is below bus voltage, the battery supplies the
busloads. The D.C. ammeter, installed in the instrument panel, indicates the discharge or charge on
the battery after the engine is started. All electrically operated motors, lighting systems and other
electrical component circuits are protected by push button thermal circuit breakers. Switches and
instruments required for operation of the aircraft electrical system are installed in the instrument panel
and engine control switch panel.
The 24-volt D.C. electrical system depends upon electrical power from three different sources:
battery, external power and the generator. With the engine operating and the generator on the line,
electric power from the generator is provided through a circuit breaker to the main bus.

BATTERY AND EXTERNAL POWER

One or two 24-volt storage batteries provide power to the circuit breaker through relays. A two-
position (BAT OFF-ON) switch located on the engine control switch panel controls the relays.
Placing the battery switch in the ON position closes the relay to supply power to the circuit breaker
bus from the battery or external power. Placing the battery switch in the OFF position de-energizes
the battery relay and terminates the supply of power to the electrical system.

BATTERY SERVICING

INITIAL SERVICING OF A DRY CHARGE GE50C BATTERY IS AS FOLLOWS:
A. Remove seals (if present) from cells.
Effective: 12/17/03
THRUSH AIRCRAFT INC - T660 TURBO THRUSH
AIRCRAFT MAINTENANCE MANUAL

GENERAL DESCRIPTION

POWER DISTRIBUTION

F or when performing maintenance
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