TM 1-1520-253-23
c. The aft fuselage and pylon sections together contain the aft transmission and the auxiliary power unit. The
engines are mounted inside nacelles at the base of the pylon on each side of the / fuselage. A hydraulically operated
cargo ramp is at the aft end of the fuselage section. A jettisonable door hatch is in the center of the cargo door. The
pylon houses the aft transmission, rotor shaft, and the combining transmission. The leading edge of the pylon is hinged
on each side. It opens at the center line for access to the combining transmission.
d. The landing gear consists of four assemblies: two forward and two aft. The two forward assemblies have dual
wheels. Each aft assembly has a full-swivel single wheel. The aft wheels can be locked in the trailing position. A power
steering unit is installed on the aft right landing gear assembly.
1.2.4 Engine Group. There are two gas turbine, model T55 engines, one mounted externally on each side of the pylon.
They supply torque to power the drive and rotor systems. Fuel, hydraulic, and electrical connections to the powerplant
have quick-disconnect couplings at the fuselage for ease in changing powerplants. The powerplant is started by a
hydraulically powered starter. The starter provides power to motor the seven-stage compressor section. Air is inducted
at the front of the engine, compressed, mixed with fuel, and ignited in the combustion chamber. Combustion gases drive
four rotors. The first two rotors drive the seven-stage compressor turbine after the engine is started. The last two rotors
drive the power turbine output shaft with the final power output taken off the front of the engine by the engine
transmission.
1.2.5 Flight Control Group. The flight control system is electrohydraulically operated and powered by two independent
hydraulic boost systems. Control inputs from the cockpit are transmitted through mechanical linkage to the Integrated
Lower Control Actuator (ILCA). The ILCA then transmits individual control motions to the first and second stage mixing
units. The mixed outputs are then transmitted through a series of push-pull tubes to the upper dual-boost actuators
attached to the forward and aft swashplates. The flight control system is divided into seven main sections:
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Cockpit controls
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Closet controls between stations 95 and 120
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First and second stage mixing controls
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Forward upper controls
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Tunnel controls
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Aft fuselage controls
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Aft upper controls
1.2.6 Access Panels. Doors. and Fairings. Access panels, doors, and fairings consist of panels, doors, fairings, covers,
baffles, and work platforms. Inspection of the helicopter and its components can be done through principal access
panels. Principal access and inspection openings are shown in Figure 1-4 and listed in Table 1-2.
