TM 55-1520-240-23-10
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HEAD UP DISPLAY
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The head up display (HUD) consists of signal data
converter (SDC), the converter control (CCU), air data
transducer, inclinometer and the display unit (DU),
consisting of the optical unit (OU) and power supply
calibration unit (PSCU). The HUD display allows the
pilots using the aviator night vision imaging system
(ANVIS) during night flight operations to receive flight
data about the aircraft through symbology without
viewing the instrument panel. The OU is attached to the
ANVIS. The HUD has two programming modes and one
operational mode which allow the pilot and copilot to
independently select the symbology for their respective
display modes from a master set of symbols in the
signal data converter. Power to operate the HUD system
is taken from the 26vac essential bus and the 28vdc
bus through circuit breakers located on the copilots’s
circuit breaker panel, labeled HUD REF and HUD SYS.
Pilot and copilot can independently select from four
normal symbology modes and four declutter modes
that can be pre-programmed. Declutter mode has four
vital symbols that will always be displayed: Air speed,
Altitude (MSL), Attitude (pitch and roll), and Engine
Torque(s). An adjust mode, during operation, is used to
calibrate the barometric altitude, pitch and roll. A switch
on the collective stick allows for brightness control and
selection of one of four displays. The system self test is
divided into power-up or operator initialized built-in-test
(BIT) and in-flight BIT. A failure of the SOC pilot’s DU,
or copilot’s DU will illuminate the CCU FAIL light and
display a FAIL message on display unit.
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