TM 1-1520-238-T-5
8–2
SECTION I.
EQUIPMENT DESCRIPTION AND DATA
8–1.
EQUIPMENT CHARACTERISTICS, CAPABILITIES, AND FEATURES
8–1
a. Characteristics.
(1) Engine instruments measure and display engine and rotor performance.
(2) Flight instruments measure and display helicopter flight performance.
(3) Miscellaneous instruments display hydraulic pressure, fuel quantity, outside temperature and time.
b. Capabilities and Features.
(1) Engine instruments provide the means to monitor power turbine (NP) speed, rotor rpm (NR), gas
generator turbine (NG) speed, turbine gas temperature (TGT), engine oil pressure (ENG OIL), engine torque
(TORQUE), and fuel quantity. Engine instruments are self contained rectangular units with fixed numbered scales
and colored columns of lamp segments that illuminate when a corresponding numeric value is reached. The lamp
segments are divided into colored zones. The colors are red (danger zone), amber (caution zone), and green
(normal operating zone). The bottom lamp segment of each scale is a blue segment that lights to indicate
electrical power is applied to the instrument. Some instruments have three–digit readouts that display values in
numbers that are more accurate and easier to read than vertical scales. Engine instruments operate in three
modes: normal, digital blanking, and test. In normal mode, digital readouts change numbers as performance
changes. In digital blanking mode, the digital readout blanks, but the vertical displays read normally. In test mode,
vertical scales display full columns of lights and digital readouts display three eights (888).
(2) Flight instruments provide the means to monitor airspeed (forward, up, and down), altitude and gravity
(g) forces, magnetic heading to provide visual displays of helicopter attitude and flight conditions. Flight
instruments operate from direct impact air forces and static outside air pressure. Air is supplied through air inlets
and tubing. The air inlets are two Pitot tubes and two static ports. The airtight tubing has drains to let any moisture
escape. Heating elements in the Pitot tubes prevent ice buildup from blocking the air flow. Flight reference
instruments operate from power and flight data inputs. All flight instruments are edge–lighted.
(3) Miscellaneous instruments provide the means to monitor primary, secondary, and emergency
hydraulics, forward and aft fuel cell quantities, refuel indications, hours, minutes, seconds, elapsed–time, and
outside air temperature. Miscellaneous instruments receive inputs from hydraulic pressure sensors, a fuel signal
conditioner (FSC) and fuel quantity sensors, outside air sensors, and 28 VDC from the signal data converter
(SDC).
8–2.
LOCATION AND DESCRIPTION OF MAJOR COMPONENTS
8–2
a. Engine Instruments.
Engine instruments (fig. 8–1) consist of the pilot TGT indicator, pilot TORQUE
indicator, pilot ENG OIL indicator, pilot ENG–RTR RPM% indicator, pilot NG RPM% indicator, CPG selectable
digital display (SDD) panel, dim/test panel, and the SDC.
(1) Pilot TGT Indicator.
The pilot TGT indicator, located in the pilot instrument panel, has a vertical scale
display mounted above each digital readout. The left side displays turbine engine 1 values and the right side
displays turbine engine 2 values.
