The powerplant cooling system is a three-part cover
which protects the powerplant and directs the flow of air
through the powerplant compartment. Two side covers
are hinged to the upper cover and fit flush to the lower
access door when latched. The third cover is an upper
cover supported by two hinge link assemblies at the front
and at the aft end by a former which also serves as a
firewall. Lower access door covers the quick-disconnect
shelf and is hinged to the fuselage.
POWER CONTROL SYSTEM HELICOPTERS
The engine power or engine condition control system
has two subsystems. The compressor or gas producer
(N1) system, and the combustor, or power turbine (N2)
systems. Both systems are powered by 28 vdc.
The N1 system controls the gas producer
section of the powerplant. It has two circuits in
the engine condition control quadrant, a control
box, a control actuator, linkage, and ENG N1
The N2 control system controls the power
turbine section of the powerplant. The system
includes two ENGINE BEEP TRIM switches,
two EMERG ENG TRIM switches, two droop
eliminator resistors, two engine trim relays,
two emergency engine trim relays, two remote
positioning control boxes, a control actuator,
FADEC CONTROL SYSTEM HELICOPTERS WITH 74
Each engine is controlled by a separate power control
system. This power system, Full Authority Digital
Electronic Control system (FADEC), provides:
Twin engine load sharing.
Power turbine speed governing.
Transient load anticipation.
Transient torque smoothing.
Emergency power capability.
Acceleration and deceleration control.
Engine temperature limiting.
Compressor bleed valve control.
Fuel flow limiting.
Engine fail detection.
Power Assurance Test (PAT).
Engine history/fault recording.
Engine to engine communication.
Automatic switchover to reversionary backup in
event of primary error.
The FADEC system incorporates a digital electronic
control unit (DECU), a hydromechanical fuel metering
unit (HMU), a thrust control position transducer, Np
and Ng speed pickups, and a signal conditioning unit.
Cockpit controls for the FADEC are mounted in the
overhead console. The overhead console consists
of the engine condition control quadrant and FADEC
NO BREAK - WORK HARDER
Engine historical data can be uploaded and downloaded
from the DECU using EMC-32T-2, Engine Historical
Recording Terminal (EHRT).
The engine mounts provide a 3-point support, two
forward and one aft. A connecting link on the outboard
side of each powerplant provides restraint in the event
of an impact. Engine mount adapters are bolted to the
engine and fit the three structural mounts.
Chapter 6 for engine transmission.
Chapter 7 for engine starter.
Chapter 8 for tachometer generator (without 74 ).
Chapter 12 for fire detection system.
TM 55-2840-254-23 for basic engine (without 74 ).
TM 1-2840-265-23 for basic engines (with 74 ).
The exhaust system conducts the exhaust gases in a
smooth flow from the engine to the atmosphere. This
smooth flow is desirable for efficient engine operation.
The exhaust cone (tailpipe) is connected to the aft end
of the engine by a coupling.