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 WITHOUT 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,
rotor tachometer, and dual engine torquemeter. 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, and attitude
direction indicator.
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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