Electrical System; General Description; Power Distribution; Battery And External Power - Thrush Aircraft S2RHG-T65 TURBO THRUSH Maintenance Manual

THRUSH AIRCRAFT, INC – MODEL S2RHG-T65 TURBO THRUSH
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°F or when performing maintenance 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.
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.

Initial servicing of a dry charge GE50C battery is as follows:
A. Remove seals (if present) from cells.
B. Fill each cell with 1.285 specific gravity sulfuric acid to bottom of split ring. Use
only glass, rubber or plastic materials for containing battery electrolyte fluid during
servicing and wear protective clothing and rubber gloves when handling electrolyte
to prevent personal injury. Use a solution of baking soda and water to neutralize
any acid spilled on clothing, skin or any damageable surface.
C. Sway the battery from side to side to release any trapped air. Re-adjust the
electrolyte as necessary.
D. Let battery sit unused for one hour.
Effective: 05/05/04
AIRCRAFT MAINTENANCE MANUAL
ELECTRICAL SYSTEM

GENERAL DESCRIPTION

POWER DISTRIBUTION

BATTERY AND EXTERNAL POWER

BATTERY SERVICING

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