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AGUSTA AB 139 TRAINING MANUAL

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CHAPTER 76 - ENGINE CONTROLS

SECTION 76-10 - POWER CONTROL

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SECTION 76-10

POWER CONTROL

DESCRIPTION

The Engine Control System is composed of two majorcomponents: an engine mounted Fuel Management Mod-ule( FMM) including fuel pumps and filter assembly, andan off- mounted Electronic Engine Control (EEC).The associated sensors, wiring harnesses and interfacedcomponents complete the control system.

Fuel Management ModuleThe FMM is an electro-hydromechanical unit that is drivenby the engine Accessory Gearbox to modulate the enginefuel flow over the entire operational envelope of theengine. This unit supports both normal automatic andmanual mechanical backup modes of operation.

The FMM incorporates a low and a high fuel pump thatdelivers filtered, high pressure fuel to the metering portionof the unit. The pressurized fuel is routed to the fuelmetering valve which is activated by the compressordelivery pressure (P3) and the torque motor controlled bythe EEC in AUTO mode or the Ng governor cam in MAN-UAL mode using the Engine Control Lever (ECL).

The pressurizing and shut-off valve blocks the fuel sup-

plied to the nozzles until a predetermined pressure isachieved. A solenoid shutdown valve, through the OFFposition of the ENG MODE switch in AUTO mode, pro-vides one of the two independent means of shutting offfuel from the engine. The second is the ECL at the OFFposition in MANUAL mode.In order to achieve automatic or manual engine running itis required that either controls must not be in the OFFposition.

Electronic Engine Control

The EEC is a single channel control unit that in conjunc-tion with the FMM and a network of sensors controls theengine gas generator and power turbine speeds inresponse to the load demanded by the rotorcraft's rotor

system.The EEC provides electronic interface between theengine sensors and effectors as well as discrete andserial communication interfaces between the engine androtorcraft.

The EEC consists of two functionally independent sub-systems, the control and Npt (Nf) limiter subsystems.The control sub-system interfaces with engine sensors aswell as rotorcraft command signals to provide control ofthe fuel flow through the FMM torque motor such to keepconstant Nf speed within ITT, Ng and Torque maximumlimitation.

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The Nf limiter sub-system provides independent limitation

of inadvertent engine turbine overspeed. Both sub-sys-tems are isolated from one another including separatepower supplies and signal conditioning interfaces.The limiter sub-system is non-latching in operation andwill engage the FMM overspeed valve solenoid when theNf speed reaches 111% and reset the solenoid when Nfspeed falls below 109%.

OPERATION

Normal Automatic Mode

Normal automatic mode is the primary mode of operationwhich is achieved with the ENG MODE switch on theFLIGHT position and the ENG GOV switch on AUTO.In automatic mode the EEC provides automatic start,main rotor governing, torque/ interturbine temperaturematching, OEI training capability over the entire operatingenvelope without exceeding limiting parameters.

In automatic mode, control parameters from the engineand rotorcraft system are input to the EEC, which com-putes the desired fuel flow through a torque motor to set

the position of the metering valve in the FMM.In automatic mode the manual backup, through hydrome-chanical devices inside the FMM and then not visible inthe cockpit, continually tracks the actual Ng speed inorder to minimize the change in engine power when atransfer to MANUAL mode will occur either intentionally or

automatically; this condition is achieved if the ECL is on

FLIGHT position.

If the pilot selects the MANUAL mode or if a criticalengine failure should occur, the mode select solenoid isde-energized (by the ENG GOV switch in the first case orby the EEC in the second) and the system reverts to themanual backup mode.

Manual Backup Mode

Manual mode is achieved with the ENG MODE on theIDLE or FLIGHT position, the ENG GOV switch on MANand using the ENG TRIM selector to operate the EngineControl Lever.In manual mode the ECL sets the position of the 3D camof the Ng speed governor to set the position of the meter-

ing valve in the FMM in order to match the power requiredfor the load on the rotor.The minimum and maximum power allowable is reflectedby the Ng speed governor min and max stops which areset at 68.6% and 106% at sea level ISA.

Power turbine limitation is maintained, as long as the lim-iter sub-section and sensors are healthy, irrespective ofoperating mode.

During manual mode starts the ECL is placed at FLIGHTposition. In case of adverse starting conditions, enginestart enrichment is available through the ECL advance-ment.

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CONTROLS AND INDICATIONS

The engine controls are distributed as the following:

the miscellaneous panel installed on the console

the engine control panel installed on the console

the engine control lever installed on the overhead

the pilot and copilot collective grip.

The miscellaneous panel provides the following functions:

LD SHARE selector switch : TORQUE = the engine control system performs the

torque matching

TEMP = the engine control system performs the ITTmatching

NOTE The ZY green triangles are displayed on the leftand right side of TQ or ITT legends on the MFD

(Main page or Cruise page) in accordance withthe selection.

The Engine Control Panel provides the following functions:

ENG 1 (2) MODE selector switch :

OFF = when the N. 1 (2) engine not running or itshuts down the engine or during the N. 1 (2) enginedry motoring procedure when Manual selected.

IDLE = allows the N. 1 (2) engine starting, the mini-mum on ground (65% Npt)) and the N. 1 (2) enginestabilization for a period of 60 sec during the shutdown phase; during the N. 1 (2) engine wet motoringprocedure both Auto and Manual mode.

FLT = allows the N. 1 (2) engine quick starting at theflight nominal speed (100% NF).

OEI TNG electrical self-retaining switch :

Central position = OEI TNG function deactivated. # 1 position = the N. 1 engine goes to TRAINING

mode, while the N. 2 engine goes to STANDBYmode (90% NF).

# 2 position = the N. 2 engine goes to TRAININGmode, while the N. 1 engine goes to STANDBYmode (90% NF).

NOTE The OEI TNG is disabled or cancelled if someoperative conditions are missing and the self-retaining switch centers automatically.

The Engine Control Lever provides the following functions:

ENGINE N. 1 (2) START pushbutton switch :

when pressed the N. 1 (2) engine starting / drymotoring / wet motoring is engaged in Manual mode.

E.C.L. position : OFF = when the N. 1 (2) engine not running; or

when the N. 1 (2) engine shuts down in Manualmode; orduring the N. 1 (2) engine dry motoring procedure inManual mode.

MIN = the N. 1 (2) engine running at 65% 1% NF inManual mode.

NOTE This position is provided with a mechanical latch.Pull the lever before leaving the MIN position.

FLIGHT = the N. 1 (2) engine running at 100% NFboth Auto and Manual mode.

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NOTE 1. The FLIGHT position must always be set dur-ing the Auto mode operation.

NOTE 2. This position is provided with an electro-mag-netic latch. This latch is removed when the ENG1/2 GOV AUTO/MANUAL selector switch is set toMANUAL.

NOTE 3. An optical sensor is installed inside the lever todetect if the lever is out of FLIGHT position in

AUTO mode.When this condition exists, a caution alarm is dis-played in the CAS.

MAX = allows engine maximum power when theManual mode is operative.

The pilot and copilot collective grips provide the following

functions: ENG 1 (2) GOV AUTO/MANUAL selector switch :

AUTO = allows the N. 1 (2) engine automatic starting/ wet motoring / dry motoring and provides the N. 1(2) engine automatic control.

MANUAL = allows the N. 1 (2) engine manual start-ing / wet motoring / dry motoring and provides the N.

1 (2) engine manual control.NOTE When in Manual mode, the amber legend MAN in

reverse video is displayed on the left side of theTQ scale (MFD - Main and Cruise pages) and PIscale (PFDs). The legend flashes for 5 sec beforebeing displayed steady state in amber.

ENG 1 (2) TRIM selector :

+ (up) = controls the N. 1 (2) ECL movement

towards the MAX position when in Manual mode. (down) = controls the N. 1 (2) ECL movement

towards the MIN position when in Auto/Manual mode.

NOTE In Auto mode the selector is still operative but witha reduced range between FLIGHT and MIN.However this procedure is not standard becausethe ECL is out of FLIGHT position requestedduring normal operation.

TQ LIM pushbutton switch :

when pressed the torque limiter function is activated,the AEO ENGINE TOTAL TORQUE is limited to acombined torque value of 228%. The OEI ENGINETORQUE is not affected

when pressed a second time, the torque limiter functionis deactivated so full power is available from engines.

NOTE When the torque limiter is activated, the advisorymessage TQ LIMITER ON is displayed in theCAS.

100% / 102% RPM selector switch :

100% = set the NR / NF to 100%

102% = set the NR / NF to 102%

NOTE This last operation is provided by the pilot collec-tive grip only.

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MAINTENANCE INFORMATION

The circuit breaker panel must be removed in order toconnect / disconnect the engine control cables from theengine control levers.

The position of the plates securing the engine controlcables to the engine control levers must be recordedbefore removal.

The adjustment of the engine control cables is required

after replacement of the engine control lever assembly,engine control cable, engine control converter, enginecontrol converter bracket.

The routing of the engine control cables must berecorded before removal.

The adjustment of the engine control cable is carriedout by:

Rig the engine control converter to the FLIGHT posi-tion with a centering pin

Connect the cable end to the engine control con-verter (if installing a new cable otherwise disconnectthe cable from the engine control lever)

Set the engine control lever at FLIGHT position

Connect and adjust the cable rod end to the enginecontrol lever using the cable adjustment nut as nec-

essary Make sure you can see the thread of the control

cable rod end through the inspection hole otherwiseadjust the cable attachment to the structure usingthe attachment adjustment nut as necessary

The plates securing the engine control cables must

be installed at the middle of the slot of the powercontrol lever (in case of engine control cablereplacement).Their position can be changed to adjust the cabletravel against stops.

The position of the shims between the engine controlconverter and the engine control converter bracketmust be recorded.Shims must be adjusted if the movement of the enginecontrol converter shaft is not free and smooth afterengine control converter replacement.

The engine control converter must be removed with theengine control lever in FLIGHT position.

The engine control converter must be installed aligningthe reference key on the FMM shaft with the reference

key on the engine control converter shaft.Make sure that the teeth of the two shafts are correctlyand fully engaged.

An operation test of the Electronic Engine Control mustbe carried out after replacement.

LVDTs removal is carried out with the collective flightcontrol rigged at the mixing unit.

Adhesive tape under clamps surfaces must berenewed after removal.

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SAFETY PRECAUTIONS

The solvent is a dangerous material. Make sure thatyou know all the safety precautions and first aid instruc-tions for the solvent.

Make sure that you obey all applicable precautionswhen you use compressed air.

SPECIAL TOOLS / TEST EQUIPMENT

Engine control converter rigging pin

Mixing unit collective rigging pin (part of Flight controlsadjustment tool kit).

LEADING PARTICULARS

- Electronic engine control N. 1

Nominal supply voltage ............................................64 VAC 3from PMA when NG>40%

(primary power source)

Nominal supply voltage.............................. 28 VDC ESS. No. 1(secondary power source)

- Electronic engine control N. 2

Nominal supply voltage ............................................64 VAC 3from PMA when NG>40%

(primary power source)

Nominal supply voltage.............................. 28 VDC ESS. No. 2(secondary power source)

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ENGINE CONTROLS OPERATION SCHEMATIC

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PILOT COLLECTIVE GRIP GENERAL LAYOUT

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ELECTRONIC ENGINE CONTROLS COMPONENT LOCATION

TM-39-76-10-002

ELECTRONIC

ENGINE

CONTROL

N 2

J40

GSE INTERFACE

CONNECTOR

ELECTRONIC

ENGINE

CONTROL

N 1

LEFT E-E BAY

RIGHT E-E BAY

B

A

A

B

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ENGINE CONTROLS (SHEET 1 OF 3)

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ENGINE INDICATING (SHEET 1 OF 3)

NOTE The baseline of the NG, ITT, TQ and Triple Tachometer indications is green all the times, even when the pointers are amberor red.

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NOTE The above legends are displayed when

the OEI condition exists or the OEI Train-ing is selected by the pilot and autho-rized by the EECs. See Section 77-40INTEGRATED ENGINE INSTRUMENTSYSTEMS for details.

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ENGINE CONTROL LEVER ASSEMBLY - REMOVAL / INSTALLATION

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ENGINE CONTROL CABLE - REMOVAL / INSTALLATION

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ENGINE CONTROL CONVERTER - REMOVAL / INSTALLATION (SHEET 1 OF 2)

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ENGINE CONTROL CONVERTER - REMOVAL / INSTALLATION (SHEET 2 OF 2)

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ELECTRONIC ENGINE CONTROL - REMOVAL / INSTALLATION

TM-39-76-10-014

MOUNT

CONNECTOR J2

ELECTRICAL

CONNECTOR P2 BONDING

CABLE

ELECTRONIC

ENGINE

CONTROL

BOLT

CONNECTOR J1

ELECTRICAL

CONNECTOR P1

FORW

ARD

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LVDTS - REMOVAL / INSTALLATION

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ENGINE N. 1 CONTROLS BLOCK DIAGRAM INTERFACE

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SPECIAL TOOLS / TEST EQUIPMENT

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