TM 55-1520-240-23-7
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LIGHTING SYSTEMS
(Continued)
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PILOT’S FLIGHT INSTRUMENT PANEL LIGHT
SYSTEM WITHOUT 17 AND 74
Description
The pilot’s flight instrument panel lights system contains
a PILOT FLT INST LTS control, autotransformer, variable
resistor, and lamps to light the instruments and the RAD
ALT dimming panel. Panel lights illuminate the following
instruments: clock, cruise guide indicator (CGI), rate
of climb, turn and slip, course, airspeed indicators, and
the dual engine torquemeter. The system also supplies
26 vac to the integral lamp in the vertical gyro indicator
(VGI) and the standby compass and 5 vac to integral
lamps in the AIMS altimeter, horizontal situation indicator
(HSI), radar altimeter, and the rotor tachometer.
Operation
Power for the system comes from No. 2, 26 vac, lighting
transformer. When the PILOT INSTR LIGHTING circuit
breaker is closed, 26 vac is applied to the PILOT FLT
INST LTS control which is used to vary the brightness of
the lamps. Should a loss of 26 vac occur on the No. 2 26
vac bus, the lamps for the turn and slip indicator can be
controlled through the secondary cockpit lighting circuit.
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