TM 55-1520-240-23-7
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LIGHTING SYSTEMS
(Continued)
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COPILOT’S FLIGHT INSTRUMENT PANEL LIGHTS
SYSTEM WITH 17 AND 74
Description
The copilot’s instrument panel light system includes a
CPLT INST LTG control 0-115 volt variable transformer,
115 to 5 volt autotransformer, and lamps to light the
instruments and the RAD ALT dimming panel. Panel
lights light the following instruments: AIMS altimeter,
cruise guide indicator, rate of climb, airspeed indicators,
and rotor tachometer. Internal lights light the following
instruments: turn and slip indicator, RAD ALT DIM
indicator (lightplate) attitude indicators, horizontal
situation indicator (HSI) and mode select panel
(lightplate), radar altimeter, attitude direction indicator,
and dual engine torquemeter.
NO BREAK - WORK HARDER
The copilot’s clock is lighted by a 28 vdc circuit.
Operation
Power for the 5 vac system comes from 115 volt No.
1 ac bus. When INSTR LIGHTING circuit breaker is
closed, 115 vac is applied to the CPLT INST control,
which varies the 5 volt output to vary the brightness of
the lamps.
NO BREAK - WORK HARDER
When the CPLT CLOCK circuit breaker is closed, 28
vdc from No. 1 essential bus is connected to the clock.
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