TM  1-1520-240-10 4-1-22            No. Symbol Source Range/Description 19    Sensor, Fire Warnings Light Plate Ass’y Cockpit ATT (failure of copilot VGI), MSL, IAS, FIRE; ATT, MSL, and IAS can be cleared from display by selecting “ACK” (See NOTE). FIRE cannot be cleared. 20    Horizon Line (pitch, roll) Vertical Gyro, Co- pilot Pitch: "30_ Roll: 0 - 359_ 21    Display Mode Number HUD System 1N - 4N for normal modes, 1D - 4D for declutter modes 22    Torque Limits Torque Transduc- er (> 100%, solid box) (>123%, thresholds, solid box flashes) 23    Torque - Numerics Torque Transduc- er 0 - 130% (flashes when engine torque separation is greater than 5% threshold) Max % torque split between cockpit pan- el and HUD is 3% 24    Ground Speed Doppler 0 - 999 knots/ 0 -530 km/h (dependent on doppler) 25    Indicated Airspeed Air Data Trans- ducer 0 - 220 knots (no symbol 00 knots and below, reappears at 02 knots) 26    Attitude Reference In- dicator HUD System Represents helicopter 27    Engines Temperature Thermocouple Amplifiers 0 - 999_C (0 - 755_C, 2_units; 776_C - 999_C, 1_units) Max split between cockpit and HUD is "15_ 28    Distance to Waypoint Doppler 0 - 999.9 km 29    Bearing to Waypoint - Numeric Doppler 0 - 359_ NOTE:   After ACK is used to acknowledge a fault, the fault will not reappear until BIT is selected or power is cycled off and on. Figure  4-1-9.   CH-47D HUD Master Mode Symbology Display (Sheet 3 of 3) 4-1-32.  Operation. 4-1-33.  Starting Procedure. 1.   ADJ/ON/OFF switch - OFF. 2.   Optical unit support clamps — Installed on ANVIS. Verify clamps can be rotated. NOTE Check surface of lense for cleanliness. Clean in accordance with TM 11-5855-300-10. 3.   DU lens — Check. WARNING Failure  to  remove  the  ANVIS  neck  cord prior to operation of the HUD may prevent egress from the aircraft in an emergency and may result in serious injury or death. 4.   ANVIS neck cord — Removed. 5.   Optical unit - Install on ANVIS. Attach Opti- cal  Unit  (OU)  to  either  ANVIS  monocular housing.  Do  not  tighten  OU  clamp  com- pletely with thumbscrew at this time. The OU (display) may have to be rotated to hori- zon after the system is operating. The helmet may now have to be rebalanced. 6.   EYE SELECT switch on PSCU — L or R. WARNING CCU ADJ/ON/OFF switch must be OFF be- fore  connecting  or  disconnecting  quick release connector. CAUTION The AN/AVS-7 system should not be used if  the  quick-release  connector  is  not  in working order. 7.   PSCU   —   Connect.   Connect   PSCU   to quick-release   connector   by   rotating   the connector engagement ring.