a. Master Caution Lights. The pilot and gunner MASTER CAUTION lights (Figure 2-23) illuminate when a caution panel light illuminates. This illumination alerts the pilot and gunner to check caution panels for the spe-cific fault condition.
b. Caution Panels (Figure 2-23).
(1) Caution Panel Lights. The pilot and gun-ner caution panel lights illuminate to identify specific fault conditions. The caution light lettering is readable only when the light illuminates. The light will remain illumi-nated until the fault condition is corrected.
(2) Test/Reset and Test Switches. The pilot caution panel has a TEST/RESET toggle switch. The gunner caution panel has a TEST switch. Momentarily placing the pilot switch to the test position will cause pilot caution panel and MASTER CAUTION lights in both pi-lot’s and gunner’s station to illuminate. Pressing the gun-ner’s test switch will cause gungun-ner’s caution panel to illu-minate. Testing of the system will not change the existing fault condition indications. Momentarily placing the pilot switch in the RESET position will extinguish and reset the pilot and gunner MASTER CAUTION lights so they will illuminate again should another fault condition occur.
(3) Bright-Dim Switches. The caution panels have a BRIGHT-DIM (pilot), BRT-DIM (gunner) switch to control the brightness of the panel caution lights and the MASTER CAUTION lights. This switch will not function if the pilot CONSOLE rheostat (Figure 2-21) of the gun-ner INST LT rheostat (Figure 2-12) is in the OFF position.
The caution lights and the MASTER CAUTION lights will be at full brightness when the pilot/gunner rheostats are in the OFF position.
c. Electrical Circuit. The master caution system is powered by the dc essential bus and protected by the CAUT LT circuit breaker.
MS018113
Figure 2-22. Low Airspeed Indicator (LAI)
CAUTION PANEL CAUTION PANEL
WORDING FAULT CONDITION WORDING FAULT CONDITION
ENG OIL PRESS Engine oil pressure below operating minimum (25 psi).
DC GEN DC generator has failed or GEN switch is OFF.
TRANS OIL PRESS Transmission oil pressure is below minimum (below 30 psi).
RECT Transformer rectifier unit has failed or alternator is not supplying power.
ENG OIL BYPASS Engine oil bypass switch OFF - Oil system level down 3.8 quarts from full.
RDRCM INOP GOV EMERG
Radar countermeasures set has failed.
Governor switch in emergency position.
Engine oil bypass switch AUTOMATIC - Oil system level down 3.8 quarts from full and bypassing cooler.
ALTER Alternator has failed. ALTNER switch is OFF, or ROTOR RPM is below 91% .
GOV EMERG Governor switch in emergency position.
TRANS OIL BYPASS Transmission oil bypassing oil cooler. *HUD INOP Head up display has failed.
*FCC INOP Fire control computer has failed.
TRANS OIL HOT Transmission oil temperature is at or above red line.
*LASER ARMED LASER ARM switch is in 1st or LAST position.
ENG FUEL PUMP One side and/or both sides of engine fuel pump producing low pressure.
IRCM INOP Indicates system failure or 60 second cooldown period, then light should go out.
*IFF CODE HOLD Cold hold switch in the hold position.
ENG CHIP Metal particles in engine.
42 CHIP Metal particles in 42 degree gearbox. IFF CAUTION IFF system inoperative.
90 CHIP Metal particles in 90 degree gearbox. EXT PWR External power receptacle door open.
TRANS CHIP Metal particles in transmission. #1 HYD PRESS System 1 hydraulic pressure is low.
FWD FUEL BOOST Forward fuel boost pump pressure low (below 5 psi).
*EMERG HYD PUMP ON
Emergency hydraulic pump is operating.
FUEL FILTER Fuel filter is partially obstructed. *GUN ELEV STOWED Turret weapon is in stowed position.
FUEL LOW Low fuel quantity. #2 HYD PRESS System 2 hydraulic pressure is low.
AFT FUEL BOOST Aft fuel boost pump pressure low (be-low 5 psi).
CHIP DETECTOR Metal particles in transmission, engine, 42 degree gearbox, or 90 degree gearbox.
*Illuminate aviation green.
Figure 2-23. Pilot and Gunner Caution Panels
2-77. RPM HIGH-LOW LIMIT WARNING SYSTEM.
The system provides an immediate warning to check in-struments for high or low rotor rpm or low engine rpm.
The audio warning will be heard in the pilot and gunner headsets. The audio is a varying oscillating frequency starting low and building up to a high pitch, on for 0.85 second interval, then off for 1.25 seconds, then repeating cycle. The light warning and audio warning functions when the following rpm conditions exist:
a. Warning Light Only:
(1) For rotor rpm of 102-104 percent (High Warning).
(2) For rotor rpm of 93-95 percent (Low Warn-ing).
(3) For engine rpm of 93-95 percent (Low Warning).
(4) Loss of signal (circuit failure) from either ro-tor tachometer generaro-tor or power turbine tachometer generator.
b. Warning Light and Audio Warning Signal Combination:
(1) For rotor rpm of 93-95 percent and engine rpm of 93-95 percent (Low Warning).
(2) Loss of signal (circuit failure) from both rotor tachometer generator and power turbine tachometer generator.
NOTE
It is possible to have an unmodified warning system in the aircraft. On un-modified warning systems, an audio signal will be heard if either rotor or en-gine RPM drops below low limits.
c. RPM Warning Light. The RPM light (Figure 2-6) illuminates (red) to provide a visual warning of high or low rotor rpm or low engine rpm. For low rpm warning, the audio warning functions in conjunction with the light.
d. RPM Switch - Low Audio. The pilot RPM switch (Figure 2-10) OFF position prevents audio warning from functioning for engine starting when the audio might be objectionable. The switch automatically resets to WARNING position when the engine and rotor reach nor-mal rpm.
e. Electrical Circuit. The RPM high-low limit warn-ing system is powered by 28V dc essential bus and pro-tected by the RPM WARN SYS circuit breaker.