CONTROLLING - DESCRIPTION AND OPERATION

** ON A/C NOT FOR ALL

1. General
The FULL AUTHORITY DIGITAL ENGINE CONTROL (FADEC) provides full range of engine control to achieve steady state and transient engine performances when operated in combination with aircraft subsystems. The FADEC System consists of a dual channel Electronic Control Unit (ECU) and the following peripherals:

Hydromechanical Unit (HMU)
Dedicated Permanent Magnet Alternator (PMA)
Variable Stator Vane (VSV) and Variable Bleed Valve (VBV)
High Pressure Turbine Clearance (HPTC) control valve
Low Pressure Turbine Clearance (LPTC) control valve
Rotor Active Clearance (RAC) control Valve
Starter Air Valve (SAV) and ignition components
Thrust Reverser control
Fuel return valve control
Engine Sensors
Electrical harness
Burner Staging Valve (BSV)
Engine configuration plug.

The ECU is a vibration isolated single unit mounted on the fan case, no forced air cooling. It is a part of the basic engine equipment.

** ON A/C NOT FOR ALL

2. System Description

A. Full Authority Digital Engine Control (FADEC)

(1) FADEC Functions
The FADEC system operates compatibly with applicable aircraft systems to perform the following functions.

Full Authority Digital Electronic Control - Schematic ** ON A/C NOT FOR ALL

(a) Gas generator control for steady state and transient engine operation within safe limits.

Fuel flow control
Acceleration and deceleration schedules
VSV and VBV schedules
Turbine clearance control
Idle setting.

(b) Engine limits protection

Engine overspeed protection in terms of fan speed and core speed to prevent engine running over certified red lines
Engine turbine outlet gas temperature monitoring.

Automatic engine thrust rating control
Thrust parameter limits computation
Manual power management through constant ratings versus throttle lever relationship:
take-off/go-around at full forward throttle lever position
flex take-off at constant intermediate position whatever the derating
other ratings (max continuous, max climb, idle, max reverse) at constant unique throttle lever position.
Automatic power management through direct engine power adjustment to the autothrust system demand.

(d) Automatic engine start sequencing

Control of starter valve ON/OFF
Control of HP fuel valve (ON/OFF on ground, ON in flight)
Control of fuel schedule
Control of ignition ON/OFF
N1, N2, WF, EGT monitoring
Abort/Recycle capability on ground.

(e) Thrust reverser control

Control thrust reverser actuation (deploying and stowing)
Control of engine power during reverser operation
engine idle setting during reverser transient
Control of maximum reverser power at full rearward throttle lever position
Restow command in case of non commanded deployment.

(f) Engine parameters transmission for cockpit indication

Primary engine parameters
Starting system status
Thrust reverser system status
FADEC system status.

(g) Engine condition monitoring parameters transmission

(h) Detection, isolation, accommodation and memorization of its internal system failures

(i) Fuel return valve control
FADEC controls the ON/OFF return to the aircraft tank in relationship to:

Engine oil temperature
Aircraft fuel system configuration
Flight phases.

(2) Hydromechanical Control

Hydromechanical Unit (HMU) ** ON A/C NOT FOR ALL

The hydromechanical unit (HMU) is installed on the aft side of the accessory gearbox at the extreme left hand pad. It receives electrical signals from the electronic control unit (ECU) and converts these electrical input signals through torque motors/servo valves into engine fuel flow and hydraulic signals to various external systems. Engine fuel is the hydraulic medium.

(3) Functional Interfaces

Functional Interfaces - Block Diagram ** ON A/C NOT FOR ALL

(4) Additional Engine Sensing

Full Authority Digital Electronic Control - Schematic ** ON A/C NOT FOR ALL

B. Gas Generator Control

(1) Fuel Control

(a) General
The fuel is set by the FADEC to hold the requested N1 as limited by: N2, P3, WF, WF/P3, dN2/dt, dWF/dt.

Fuel Control Limits ** ON A/C NOT FOR ALL

The requested N1 is a function of the following logics:
TLA & power management .... Sets N1
Auto Thrust A/C Signal .... Overrides TLA
Landing configuration ..... Sets approach idle
Alpha floor signal ........ Commands max T.O.
Flex T.O. ................. Derates T.O. power
Idle N2 ................... N2 set, N1 floats
Min P3 schedule ........... N1 and N2 float

(b) Limitation description

Maximum and minimum N2 schedule.
The FADEC sets the fuel to hold the N1 providing N2 is within the limits shown in referenced illustration.
Max and Min N2 Limiting Curves ** ON A/C NOT FOR ALL
Accel and Decel limitation schedules WF/P3.
The FADEC sets the fuel to reach the N1 providing WF/P3 is within limits shown in referenced illustration.
Fuel Control Strategy Curves ** ON A/C NOT FOR ALL
N2 and WF rate.
Maximum PS3, WF, N1, N2 limitations.
Minimum PS3, WF and N2 come from the idle schedules.

(2) VSV Control
The VSV position is controlled by the FADEC. The steady state VSV schedules are more open than in transient and altitude bias allows different altitude schedules.

VSV Control-Schematic ** ON A/C NOT FOR ALL

The FADEC uses the VSV feedback signal to adjust the actual VSV position.
The VSV control loop is given on referenced illustration.

(3) VBV Control
The VBV position is controlled by the FADEC.
The VBV schedules are given on referenced figure

VBV Control-Schematic ** ON A/C NOT FOR ALL

The FADEC uses the VBV feedback signal to adjust the actual VBV position.
The VBV control loop is given on referenced figure

(4) Rotor Active Clearance Control System (RACCS)
The RACCS modulates 5th stage air compressor inlet air mix inside rotor to control clearances.
The FADEC controls the RACC valve position as a function of altitude N2 and time to provide the scheduled air flow to the rotor. A feedback valve position is used by the FADEC to indicate the RACC valve position.

(5) High Pressure Turbine Clearance Control (HPTCC)
The HPTCC valve modulates air from 5th and 9th stages to turbine shroud and also bleeds air during engine start.
The FADEC controls the valve position. A feedback signal is used by the FADEC to indicate the valve position to the desired value.

(6) Low Pressure Turbine Clearance Control (LPTCC)
The LPTCC valve modulates the fan air flow to the LPT casing.
The FADEC controls the valve position. A feedback signal is used by the FADEC to indicate the valve position to the desired value.

(7) Oil/Fuel Temperature Control
The IDG oil shall be cooled by engine fuel through an oil/fuel heat exchanger. For some aircraft operation, extra heat rejected in fuel shall be carried out of the engine fuel system through the valve fuel return valve (FRV) in order not to exceed defined temperature limits (either engine fuel/oil temperature or IDG oil temperature) (Ref. AMM D/O 73-10-00-00).
FADEC performs this temperature control using the engine oil temperature and engine fuel measurement. FADEC has two actions depending on the temperature values and the aircraft flight conditions:

command the FRV in order to permit a fuel return to the aircraft tank
increase the engine speed (which leads to a decrease in temperature of the cooling fuel flow).

The "open FRV" command can be overridden to shut off by the aircraft system from a discrete signal sent through EIU.
The fuel return valve controls 2 levels of flow back to tank:

First level - controlled by ECU from engine oil temperature corresponding to a first step of IDG temperature
Second level controlled by thermostatic valve from engine fuel temperature corresponding to a second step of IDG temperature (Ref. AMM D/O 73-10-00-00).

A "close" command from the HMU interrupts both fuel flows to the aircraft (Ref. AMM D/O 73-10-00-00)
The FRV shuts off (no fuel return)

when IDG oil temperature does not exceed defined temperatures (see above)
when FADEC receives an aircraft discrete signal when the engine is shut down.

FADEC automatically increases the engine idle speed from engine oil temperature corresponding to third step of IDG oil temperature (this step is between first and second step). This function is inhibited when the aircraft is on ground.
Exceedance of engine oil temperature is indicated by a warning in the cockpit by an ARINC word.

Control Limits for Control System ** ON A/C NOT FOR ALL

(8) Burner Staging Valve Control
(Ref. AMM D/O 73-10-00-00)

C. Engine Limits Protection

(1) General
The FADEC prevents inadvertent overboosting of the expected rating (N1 LIMIT or N1 TARGET) during power setting.
FADEC provides engine overspeed protection for N1 (LOW ROTOR SPEED) and N2 (HIGH ROTOR SPEED) in order to prevent engine exceeding certified limits.

Control Limits for Control System ** ON A/C NOT FOR ALL

The FADEC monitors EGT and sends an appropriate message to the cockpit display in case of abnormally high EGT during start.
The FADEC also provides Max P3 protection through the fuel control limitations (Ref. Para. 3.).
Mechanical protections are also provided on WF and fuel pressure by mechanical means.

(2) Overspeed Protection
The engine overspeed protection is provided by:

Two electrical N2 governors (one per channel)
Two electrical N1 governors (one per channel)
One mechanical N2 governor which is included in HMU.

The electrical governors operate with the engine control laws or the fuel metering valve to limit rotors speed to red line values.

Electrical Limit Governors ** ON A/C NOT FOR ALL

Each channel receives its dedicated N1 and N2 speed signal, but can operate with cross channel data. The governors operate valid signals only.
Although aerodynamically limited, N1 is also protected by a VSV failure closure when N1 reaches an overspeed. This limits the energy to the L Protor and limits its maximum speed to a lower aerodynamic value.

(3) EGT Limit Protection
During starting sequences the FADEC monitors the EGT. (Ref. AMM D/O 80-00-00-00)

D. Power Management

(1) Rating Control

(a) FADEC integrates all the engine thrust setting curves to provide automatic engine thrust ratings control.
FADEC computes power management LIMIT and COMMAND parameters. These parameters are available for the following engine thrust modes:

MAXIMUM TAKE-OFF and GO-AROUND (TO/GA)
FLEXIBLE TAKE-OFF (FLX TO)
MAXIMUM CONTINUOUS (MCT)
MAXIMUM CLIMB (MCL)
IDLE
REVERSE.

The rating distribution in the flight envelope is given in the referenced illustration.

Rating Distribution ** ON A/C NOT FOR ALL

All transitions are blended and automatic.
The rating structure is based on EGT limits hold above corner point and thrust flat rated below corner point.

Rating Structure and Take-off Rating ** ON A/C NOT FOR ALL

The implementation is done by controlling the corrected Fan speed which correlates closely with thrust at given Mn and altitude.

Rating Structure and Take-off Rating ** ON A/C NOT FOR ALL

For take off rating, the FADEC controls the FAN speed corrected to ambient temperature to avoid Mn effect during take-off. The control is only a function of PO for altitude effect and TO for ambient temperature effect.

Rating Structure and Take-off Rating ** ON A/C NOT FOR ALL

For the other rating, the FADEC controls the fan speed corrected to total temperature. That corrected fan speed is composed of two terms, the first term to take into account the altitude and temperature effect at a constant Mn = 0.3 and a corrective factor for an effect compensation.

MXCN, MXCL, Ratings Structure ** ON A/C NOT FOR ALL

ECS bleed and anti-ice bleed are also taken into account by the FADEC to compute the corrected fan speed at a given rating.
ECS bleed is taken into account by a Delta N1K applied to the N1K computed from the rating curves.

ECS Bleed Effect ** ON A/C NOT FOR ALL

The purpose is to keep the same EGT with and without ECS bleed.
Anti-icing bleeds are taken into account by ambient temp. applied to the real one.
This has for effect to translate the corner point.

Anti-Ice Bleed Effect ** ON A/C NOT FOR ALL

Engine rating is defined by the configuration of a rating plug on the ECU. The FADEC identifies the rating available.
ECU have memory provisions for three different engine ratings.

(b) Flex Take-off
FLEXIBLE TAKE-OFF rating is set by the assumed temperature method with the possibility to enter via the MCDU any assumed temperature value to the one for the maximum derate allowed by the certifying agencies. The purpose is to obtain derated thrust.
FADEC permits:
Flexible take-off procedure with constant retarded throttle lever position, allowing the application of full take-off power at full forward throttle lever position is selected.
At this given retarded throttle lever position, and in the flex TO mode, the FADEC assures that the thrust obtained all along the FLEXIBLE TAKE-OFF at ambient temperature (T1) and with assumed temperature (TA), is the same as thrust obtained during MAXIMUM TAKE-OFF at TA actual ambient temperature.

(c) Idles
The FADEC system controls idle speed:
MINIMUM IDLE sets the minimum fuel flow requested for ensuring correct aircraft ECS system pressurization as defined in the referenced illustration and compatible with specific system requirements, such as:

ECS Bleed Effect ** ON A/C NOT FOR ALL

Aircraft Configuration
Minimum Aircraft Accessories Speed
Bleed for engine de-icing
Minimum permissible core speed
Maintain engine oil temperature within max limits.

APPROACH IDLE is set at an engine power which allows the engine to achieve the specified GO-AROUND acceleration time. APPROACH IDLE is set in response to an aircraft request signal.

(d) Reverse
The FADEC system controls the engine thrust rating during reverser operation. Engine power is set automatically by the FADEC to the level required for correct deploy and stow operations in all ambient conditions.
The maximum reverse rating power is automatically controlled by the FADEC system versus all ambient conditions, with a unique maximum reverse throttle position.
In normal operation, the FADEC system sets the engine at idle as long as the reverser is in transit. When the thrust reverser is fully deployed on ground or fully stowed, N1 follows throttle demand.

(2) Thrust Setting

(a) General
Two thrust setting modes are available, the autothrust mode and the manual mode. The mode selection is dependent on throttle levers position and upon the autothrust activation/deactivation logic.
Throttles move over a sector divided into three areas where autothrust system (ATHR) can be activated or not:

Throttle Lever Definition ** ON A/C NOT FOR ALL

In the rear region (from 5 up to and excluding 4) ATS cannot be activated.
In the middle region (from and including 4 up to and including 2) ATS can be activated.
In the forward region (from 2 to 1) ATS cannot be activated.

TAKE-OFF and FLEX TAKE-OFF is performed manually.
The thrust setting general arrangement is given on.

Thrust Setting General Organization ** ON A/C NOT FOR ALL

(b) ATHR activation/deactivation

ATHR Activation/Deactivation ** ON A/C NOT FOR ALL

The autothrust function (ATHR) can be engaged or active. The engagement logic is done in the FMGC and the activation logic is implemented into the ECU. The activation logic in the ECU unit is based upon two digital discretes ATHR engaged, ATHR active, from the FMGC, plus an analog discrete from the instinctive disconnect pushbutton on the throttle.
The ATHR function is engaged automatically in the FMGC by auto pilot mode demand and manually by action on the ATHR push button located on the flight control unit (FCU).
The ATHR deactivation and ATHR disengagement are achieved by action on the disconnect pushbutton located on the throttle levers or by depressing the ATHR pushbutton provided that the ATHR was engaged, or by selection of the reverse thrust.
If the Alpha Floor condition is not present, setting at least one throttle lever forward of the MCT gate leads to ATHR deactivation but maintains ATHR engaged ; the thrust is controlled by the throttle lever position and ATHR is activated again as soon as both throttles are set at or below MCT gate.
If the Alpha Floor condition is present, the ATHR function can be activated regardless of throttle position.
When ATHR is deactivated (pilot's action or failure), the thrust is frozen to the actual value at the time of deactivation. The thrust is tied to the throttle lever position as soon as the throttles have been set out of the MCT or MCL positions.
The ATHR is active if:
O less than or equal to TLA < MCT or (TLA = MCT and selected mode FLEXTO) or Alpha Floor condition

and - FCU discretes set to 1

ATHR active = 1

ATHR engaged = 1

and - Deactivation condition is not present.

1 The thrust is frozen to the N1 actual if (memo thrust setting):

a ATHR was active in the FADEC unit

and throttle is in MCT gate or MCL gate
and one of the deactivation conditions is present ATHR not engaged (from the ECU)
or N1 target not valid
or instinctive disconnect condition.

b Thrust was frozen

and condition to switch to manual thrust setting not present
and condition to switch to automatic thrust setting not present.

2 The thrust is controlled manually (i.e., function of TLA position) if:

a The throttles are not in the ATHR area.

b ATHR setting or thrust was frozen

and TLA MCT and TLA MCL
and one of the deactivation conditions is present.

c ATHR setting or the thrust was frozen

and the deactivation condition not present
and the FCU discrete ATHR active is not present.

d Manual thrust was selected

and condition to switch to automatic mode not present.

e Power up condition.

(d) Manual Thrust Setting

1 General
In manual thrust setting mode, power management COMMAND parameter is calculated as a function of throttle lever angle (TLA) as follows:
Throttle lever angle versus rated thrust relationship is as shown on Figure

(FN-TLA) Relationship ** ON A/C NOT FOR ALL

A forward action on the throttle lever does not lead to a decrease in thrust. A rearward action on the throttle lever does not lead to an increase in thrust.
TLA versus rated thrust is consistent regardless of ambient conditions. TAKE-OFF/GO-AROUND ratings are always achieved at full forward throttle lever position (except in Alpha-floor mode).
Other ratings (MAX CONTINUOUS, MAX CLIMB. IDLE, MAX REVERSE) are achieved at constant throttle lever positions.
FLEXIBLE TAKE-OFF for a given derating is achieved at constant retarded throttle lever position.

2 Thrust Limit mode selection
Throttle lever is used as a rating mode selection device. By receiving the throttle lever position signal, the ECU permanently computes thrust limit ratings, selects the corresponding limit value and sends it to the cockpit.
Thrust limit mode selection is achieved by manually setting the throttle to the corresponding unique position.

Autothrust Discretes Processing ** ON A/C NOT FOR ALL

MAX CLIMB rating on position 3
MAX CONTINUOUS rating on position 2
MAX TAKE-OFF/GO-AROUND rating on position 1 (MTO/GA)

When the throttle lever is positioned between two unique positions, the ECU selects the limit of the higher mode for display

N1 Limit and Limit Modes ** ON A/C NOT FOR ALL

When both throttle positions select two different modes the rating limits sent by the two ECU are different. The AFS takes into account the highest one.
On ground, as soon as the ECU is powered ON (engine not running), it is possible to check computed thrust limit parameter values against performance manual by positioning the throttle on the various unique positions. (Including Flex Take-off condition).
On ground, as soon as the engine is running, the computation of thrust limit parameter is initialized in MTO/GA mode.

3 Flex take-off
On ground, if a Flex TO temperature has been set on the MCDU of the FMS and has been validated (range, parity, SSM tests ...) and is higher than the static air temp., the ECU sets the MCT/FLEX TO detent point at the Flex TO (FTO) rating.
When the engine is not running, the limit mode is a function of the throttle position. When the conditions of the previous paragraph are met as soon as engine is running, the computation of the thrust limit parameter is initialized in Flex TO mode, as long as the throttle is lower than or equal to MCT.
When the engine is running, by setting the throttle lever above MCL, the value of FLEX temperature is latched in the ECU unit and the FLEX temperature value sent by the FMS is no longer considered in power management computations.
In flight, the only way to cancel the FLEX TAKE-OFF rating and to reset the MCT/FTO position to MCT rating is to set the throttle lever to less than or equal to MCL or equal to TO/GA.
In flight, changing from the FLEX TAKE-OFF thrust limit mode to MCT limit mode is achieved by setting the throttle lever in one of the two detent points - TO/GA or MCL - and by coming back to the MCT detent point.
In flight, it is not be possible to set back the MCT/FLEX TO detent point to FTO rating.
When a FLEX TAKE-OFF is performed, MAX TAKE-OFF rating is achieved by pushing the throttle lever to the full forward stop.

4 Thrust adjustment
In manual mode the actual thrust parameter controlled by the FADEC is adjusted to the level required by the throttle lever position through N1CMD = f (TLA).

(FN-TLA) Relationship ** ON A/C NOT FOR ALL

When throttle is positioned on one of the unique positions the commanded thrust parameter is the limit corresponding to this unique position.

(e) Autothrust setting

1 General
In autothrust mode the FADEC is working with N1CMD = N1 target from the AFS, taking into account that the N1 CMD is always be limited by the N1 throttle.

Thrust Setting ** ON A/C NOT FOR ALL

2 Alpha floor protection
Alpha floor protection is part of autothrust function.
When the aircraft angle of attack is greater than a threshold depending on the aircraft configuration, the alpha floor condition is reached and the ATS sends an N1 target demand equal to N1 MAX TAKE-OFF.
When receiving alpha floor protection signal through ARINC 429 data bus, the FADEC switches N1 target limitation from N1 throttle = f (TLA) to N1 MAX TAKE-OFF for any throttle position.
The alpha floor function can only be overridden by pilot's action on the ATS disconnect switches located on the throttle levers.

3 Memo Thrust Setting
When ATHR is deactivated, there are some cases where the thrust is frozen to the actual value (see para Thrust Setting) in that case the thrust is set according to logic shown on the referenced illustrations.

Thrust Setting ** ON A/C NOT FOR ALL

(3) Thrust setting

(a) Autothrust system definition and operation
The autothrust system provides automatic thrust setting (autothrust - ATHR). This is controlled through the aircraft Automatic Flight System (AFS) which is comprised of the following elements:

Flight Management and Guidance Computer (FMGC)
Flight Control Unit (FCU)
Multipurpose Control & Display Unit (MCDU).

The autothrust function is incorporated in the FMGC which is a subsystem of the AFS. The autothrust function provides automatic computation of the thrust level to be set in order to achieve the desired aircraft flight path.
There are two main modes of operation in the autothrust system:

Speed/Mach mode
Thrust mode.

The selection depends on the auto-pilot mode of operation. The desired thrust level is achieved by the thrust demand computed by the autothrust system and is transmitted to the FADEC system through the autothrust N1 target thrust parameter (ATN1EIU).
The autothrust function may be engaged or disengaged. The engagement logic is implemented in the FMGC. When the FMGC is engaged (enabled) the autothrust system can be either active or non-active. The ECU then activates the system if specific conditions are met.

(b) Aircraft autothrust function engagement
The engagement of the autothrust function may be accomplished manually or automatically in the aircraft. Manual engagement is accomplished through the A/THR pushbutton switch of the FCU, located on the glareshield. Automatic engagement is accomplished when the Takeoff/Go-Around mode of the autopilot system is engaged, or when the alpha floor function is engaged.
The disengagement of the autothrust function may be accomplished manually or automatically in the aircraft. Manual disconnection is accomplished through the A/THR instinctive disconnect pushbutton switches located on the throttle control levers or the A/THR pushbutton switch of the FCU Automatic disconnect is accomplished when all throttle control levers are in the reverse thrust region or all throttle levers are at the forward idle position. When the autothrust is engaged in the aircraft, the FMGC sets the ATHR ENG flag on its output; this becomes the EIU input to the ECU (discrete ATEN: label 034, bit 13).

(c) FADEC autothrust function activation
The autothrust mode in the ECU is set, or not set, on the basis of the following information:

Throttle Lever Angle (TLA)
autothrust instinctive disconnect pushbutton hardwired discrete signal
autothrust engagement hardwired discrete signal from the FMGC
autothrust engaged signal from FMGC (ATEN: label 034 bit 13)
autothrust active signal from the FMGC (ATON: label 034 bit 14)
flexible takeoff mode
alpha floor condition (AFPS: label 034 bit 23).

All these criteria are detailed in the following sections.
When the autothrust function is active the target thrust parameter (ATN1EIU, label 343) is used as a fan speed reference by the ECU to control the engine thrust. This target thrust parameter is computed by the FMGC and sent to the ECU via the FCU and EIU on the ARINC 429 data bus.

(d) Autothrust function control modes
There are three thrust control modes in the ECU:

1 Autothrust mode
The ECU controls the fan speed to the level required by the aircraft autothrust system (ATN1EIU), including the alpha floor protect mode. The autothrust level is limited to the current TLA position except in the alpha floor protect mode.

2 Memo Thrust mode
This is a transition mode of thrust control after deactivation of autothrust by the ECU. In this mode the ECU locks the thrust (Actual N1) at its level at the time of autothrust mode deactivation. This transition mode prevents potential thrust step changes which may occur when reverting from autothrust to manual mode at a high thrust lever position.

3 Manual Thrust mode
The ECU controls the fan speed according to the manual thrust lever position, regardless of any autothrust system demand. Other FADEC limits may also be imposed that override the manual thrust lever position.

(e) FMGC inputs to the ECU
The FMGC provides the following information to the ECU in order to activate the autothrust mode. This data is transmitted to the ECU from the FMGC via the FCU and EIU via the ARINC 429 data bus:

autothrust N1 target, ATN1EIU (label 343)
autothrust engaged, ATEN (label 034 bit 13)
autothrust active, ATON (label 034 bit 14)
new autothrust logic installed, ATVOLINSTAL (label 034 bit 15)
autothrust voluntary disengagement, ATVOLDISENG (label 034 bit 16)
alpha floor protect switch selected, AFPS (label 034 bit 23)
flexible temperature (label 214).

ATVOLINSTAL is read continuously as long as label 034 is valid. If label 034 is not valid, the ECU uses the last valid value ATVOLINSTAL except during engine start. During engine start (when label 034 is not valid), ATVOLINSTAL is considered false.
There are also two hardwired aircraft discretes that are utilized for the autothrust function in the ECU. The ECU provides a two-wire circuit for each discrete. The circuits for these discretes are shown in

Autothrust Engagement and Disconnect Discretes ** ON A/C NOT FOR ALL

and are:

FMGC autothrust engagement hardwired discrete, ATINH1F
instinctive disconnect pushbutton autothrust disconnect, ATINH2F.

The ECU processing for autothrust discretes is defined in

Autothrust Engagement and Disconnect Discretes ** ON A/C NOT FOR ALL

(f) ECU autothrust logic

1 Engine control modes in the ECU
The ECU uses information from the FMGC to activate the autothrust mode (including alpha floor protect mode) and controls speed to the autothrust N1 target (ATN1EIU) if it is within limits. If the autothrust mode is not active the ECU is in memo mode or in manual mode depending on the previous state, as explained in the following paragraphs.

2 Autothrust mode
The ECU activation and deactivation conditions for autothrust are defined herein. The overall autothrust control modes are determined by the ECU as defined in para. (g).

3 Autothrust activation
The ECU activates the autothrust mode if the engagement signals (ATINH1F and ATENVST) and the active signal (ATON) are set to true and the deactivation conditions (THROTTLLE CONDITION) are not set. The engage signal (ATENVST) is set to true when all of the following conditions are met:

Autothrust Engagement and Disconnect Discretes ** ON A/C NOT FOR ALL

Autothrust Discretes Processing ** ON A/C NOT FOR ALL

EIU labels 343 and 034 are valid
ATEN = true.

In the autothrust mode the ECU sets N1 demand equal to the aircraft autothrust target N1, ATN1EIU. The allowable N1 range is limited on the lower side by the FADEC idle constraints and on the upper side by the TLA setting (manual mode thrust setting).
In addition to the engage and active signals, the FMGC sets the alpha floor protect signal (AFPS, label 034 bit 23) to true when the alpha floor condition is true.
If the autothrust mode activation conditions are met and the alpha floor signal is set to true, the ECU enters into the alpha floor protect mode regardless of the throttle control lever position, provided that the aircraft is in flight.
In this alpha floor protect mode the ECU sets N1 demand equal to the aircraft autothrust N1 target ATN1EIU. The allowable N1 range is limited only by N1MAX on the upper side and the current TLA setting on the lower side.

(g) ATHR deactivation
The ECU deactivates the autothrust mode as shown in Figures:

Autothrust Engagement and Disconnect Discretes ** ON A/C NOT FOR ALL

Autothrust Discretes Processing ** ON A/C NOT FOR ALL

and

Autothrust Control Modes Determination ** ON A/C NOT FOR ALL

Inputs to this logic will include:

disconnect deactivation, ATDISL
Autothrust Engagement and Disconnect Discretes ** ON A/C NOT FOR ALL
autothrust engaged, ATEN (label 034 bit 13)
EIU labels 343 and 034 validity
throttle resolver angle, TRA
flexible takeoff mode
alpha floor protect switch, AFPS (label 034 bit 23)
autothrust inoperative, ATHRINOP
Autothrust Engagement and Disconnect Discretes ** ON A/C NOT FOR ALL
autothrust voluntary disengagement (label 034 bit 16)
thrust reverser position - four doors unstowed
autothrust engagement signal, ATFMDIS
Autothrust Engagement and Disconnect Discretes ** ON A/C NOT FOR ALL

ECU mode reversion is as shown in Figure depending on autothrust activation commands.

Autothrust Control Modes Determination ** ON A/C NOT FOR ALL

(h) Memo thrust mode
In memo thrust mode, the actual N1 is held to the value when the mode was entered. The allowable N1 range is limited on the lower side by the FADEC idle constraints and on the upper side by the N1 speed demanded by the throttle control lever position, or by N1MAX if alpha floor protect is present (AFPS = true) in flight only. The ECU returns to either autothrust mode or manual thrust mode as shown in Figure:

Autothrust Control Modes Determination ** ON A/C NOT FOR ALL

(i) Manual Thrust Setting

(FN-TLA) Relationship ** ON A/C NOT FOR ALL

2 Thrust Limit mode selection
Throttle lever is used as a rating mode selection device. By receiving the throttle lever position signal, the ECU computes permanently thrust limit ratings, selects the corresponding limit value and send it to the cockpit.
Thrust limit mode selection is achieved by manually setting the throttle to the corresponding unique position.

Autothrust Discretes Processing ** ON A/C NOT FOR ALL

MAX CLIMB rating on position 3
MAX CONTINUOUS rating on position 2
MAX TAKE-OFF/GO-AROUND rating on position 1 (MTO/GA)

When the throttle lever is positioned between two unique positions, the ECU selects the limit of the higher mode for display

N1 Limit and Limit Modes ** ON A/C NOT FOR ALL

4 Thrust adjustment
In manual mode the actual thrust parameter controlled by the FADEC is adjusted to the level required by the throttle lever position through N1CMD = f (TLA).

(FN-TLA) Relationship ** ON A/C NOT FOR ALL

When throttle is positioned on one of the unique positions the commanded thrust parameter is the limit corresponding to this unique position.

(j) Autothrust setting

1 General
In autothrust mode the FADEC is working with N1CMD = N1 target from the AFS, taking into account that the N1 CMD is always be limited by the N1 throttle.

Thrust Setting ** ON A/C NOT FOR ALL

E. Engine Starting/Shutdown/Ignition Control

(1) General
The ECU is able to control starting (manual or automatic), cranking and ignition using aircraft control EIU data. For this purpose, each channel of the ECU is able to command the opening and closing of the Starter Air Valve (SAV), the opening of the Fuel Metering Valve (FMV) and the energizing of the igniters.

(2) Cockpit panels
Engine starting, cranking and ignition is controlled from the following cockpit panels as shown in Figure.

Engine Panels ** ON A/C NOT FOR ALL

(a) ENG panel 115VU:

1 This panel includes:

one selector switch with three positions (CRANK/NORM/IGN/START)
two ENG/MASTER control switches (one per engine)
two ENG/FIRE/FAULT annunciators (one per engine).

(b) ENG section of overhead panel 22VU:

1 This section includes:

two ENG/MAN START pushbutton switches (one per engine) to manually control the Starter Air Valve (SAV).

(3) Start information to the ECU from EIU
The ECU receives start information from EIU ARINC data which provides the ENG/MASTER control switches position, ENG/MODE selector switch position, MAN START pushbutton switches position, ANTI ICE/ENG pushbutton switch selection (coefficient K3), and flight/ground status information.

Engine Starting Logic State Diagram ** ON A/C NOT FOR ALL

Information relative to starting is transmitted by the EIU to the ECU on labels:

label 031 for cockpit controls and flight/ground information
label 030 for nacelle anti-ice control (coefficient K3).

(4) Engine starting control and operation
The FADEC system provides control for starting, engine cranking, engine shutdown and ignition selection. For starting, either an autostart or a manual start mode can be selected.

(a) Autostart sequence
The automatic engine start operation is selected as shown in Figure.

Normal Autostart Sequence ** ON A/C NOT FOR ALL

In the automatic start mode, engine starting control of the igniters, fuel and starter air valve are under the full authority of the FADEC.

1 Ground autostart
When the autostart sequence logic is active on the ground, the ECU initiates the automatic sequence to command:

the SAV (opening and closing)
one igniter (igniter selection alternates on each start)
opening of the FMV & HPSOV.

The ECU is entirely responsible for the engine starting sequence. It provides protection of EGT limit, starter engagement time limit, and any abnormal start functioning (except stall protection) up to 7230 RPM core speed (50% N2). Stall protection is active up to 8210 RPM core speed (56.8% N2). The starter re-engagement protection is provided during the entire autostart sequence.
The ECU may abort

Ground Automatic Start Abort ** ON A/C NOT FOR ALL

or recover the start sequence due to an abnormal start (engine stall, start overtemperature limit exceedance, starter-on time limit exceedance, or no engine ignition with both igniters energized). Fault annunciation is provided to the Flight Warning Computer (FWC), which then generates warning messages to the pilot. These features are available while in the start region up to 8210 RPM core speed for engine stall and up to 50% N2 for other protection.
In case of failure of the starter air valve actuation device, the ECU logic is compatible with a manual actuation of the start valve without any additional signal.

2 Air autostart
When the autostart sequence logic is active in flight, the ECU initiates the automatic sequence to command:

the SAV (for starter assist operation - opening and closing with starter re-engagement protection)
both igniters
opening of the FMV & HPSOV.

In the event of an abnormal start, the ECU provides fault annunciation to the FWC, which then generates warning messages for pilot action. The FADEC has no authority to abort the starting sequence.
The ECU identifies the windmilling or starter assisted airstart conditions according to the flight environmental parameters and the engine parameters.
In order to cover the effects of some failures which could jeopardize the in-flight restart, the FADEC includes the automatic ignition ON and the fuel ON selections for the following conditions:

if the SAV does not open within 5 seconds
other features based on N2 acceleration rate and time to normal fuel on speed (N2 in windmilling does not reach 15% within 15 seconds of starter air valve commanded open).

In addition, to provide the most expedient recovery of the engine to idle power or above, the FADEC automatically commands the starter air valve to open whenever N2 is equal to or less than 16%. However, in the event that N2 is above 12% below 20.000 feet or above 15% at or above 20.000 feet, starter air valve position faults are not annunciated to the cockpit via ARINC.

(5) Automatic start interruption
The automatic start sequence is interrupted

Automatic Start Interruption ** ON A/C NOT FOR ALL

only with selection of ENG/MASTER control switch back to OFF position and leads to:

starter air valve closure via the ECU
igniter(s) off
closure of the FMV & HPSOV by the ECU.

(a) Manual start sequence
The normal manual engine start operation is selected as shown in Figure

Normal Manual Start Sequence ** ON A/C NOT FOR ALL

In the manual start mode, engine starting control is under limited authority of the FADEC. Starter air valve, FMV, and igniter control are controlled by the crew using a conventional procedure with only limited FADEC system interaction.

1 Manual start - starter air valve command
The pilot sets the ENG/MODE selector switch to IGN/START and pushes the MAN START pushbutton switch. As soon as these two actions are accomplished, the ECU commands the starter air valve to the open position if the engine is not running (there is no priority order for these two actions inside the ECU).
Starter air valve closure is automatically controlled by the ECU at the appropriate engine speed.
The ECU provides protection for the starter maximum speed re-engagement.
The ECU provides fault annunciation to the FWC if the starter time limit has been exceeded and engine ignition has not been detected.
In case of failure of the starter air valve actuation device, the ECU is compatible with manual actuation of the starter air valve without any additional signal.

2 Manual start - FMV and igniters command
When performing a manual start the FMV and igniter are commanded when the ENG/MASTER control switch is set from OFF to ON position. The ECU automatically commands the ignition to off at the appropriate engine speed. When each engine is running the crew releases the MAN START pushbutton switch, when all engines are running the crew sets the ENG/MODE selector switch to NORM.
The ECU provides fault annunciation to the FWC if engine ignition is not detected after 15 seconds and 115V ignition power is available.
If the ENG/MODE selector switch is set to NORM position after Engine 1 starting, and then reset to START/IGNITION position prior to Engine 2 starting, this automatically selects "Continuous ignition" on Engine 1.
ENG/MASTER control switch ON or MAN START pushbutton switch pushed with ENG/MODE selector switch in NORM position have no effect on the corresponding engine if it is not running.

3 Manual start interruption

Manual Start Interruption ** ON A/C NOT FOR ALL

The manual engine start operation may be interrupted prior to the selection of ENG/MASTER control switch ON by releasing the MAN START pushbutton switch. This leads to closure of the starter air valve

Manual Start Interruption ** ON A/C NOT FOR ALL

After ENG/MASTER control switch is selected ON, MAN START pushbutton switch selections have no effect. Interruption of the manual engine start operation in this case may be accomplished by selecting ENG/MASTER control switch OFF. This leads to:

the closure of the FMV & HPSOV
the de-energizing of the igniters (via the ECU)
the closure of the starter air valve.

4 Manual start stall advisory/abort

Manual Start Abort ** ON A/C NOT FOR ALL

In the event of an abnormal start, the ECU provides fault annunciation to the FWC, which is then used to generate warning messages for pilot action.
On the ground the ECU aborts manual start operation if exceedance of the start EGT overtemperature limit occurs. It provides protection up to 50% core speed. In flight the FADEC has no authority to abort the manual starting operation.
In case of loss of valid EIU data, the ECU continues with the manual start sequence if the ENG/MASTER control switch has been set to ON and continues with a dry crank if the ENG/MASTER control switch has not been set to ON.

(b) Engine cranking sequence
The FADEC system provides control for dry and wet engine cranking capability. ENG/MODE selector switch in CRANK position is not taken into account by the FADEC system when the engine is running, or in the process of automatic or manual start. In this case, the FADEC system retains its prior state.

1 Dry cranking
If the engine is not running, the ECU opens the starter air valve when the ENG/MODE selector switch is in CRANK position and MAN START pushbutton switch is pushed (the sequence of these actions is not significant). The manual dry crank is interrupted at any time by releasing the MAN START pushbutton switch.

Dry Engine Crank Sequence ** ON A/C NOT FOR ALL

The ECU provides the capability to launch a start sequence immediately following a dry crank sequence by selecting the ENG/MODE selector switch to IGN/START position and the ENG/MASTER control switch to ON.

2 Wet cranking
A wet crank sequence is initiated (opening of the FMV) following a dry crank procedure by setting the ENG/MASTER control switch to ON. Setting the ENG/MASTER control switch back to OFF position leads to dry crank

Wet Engine Crank Sequence ** ON A/C NOT FOR ALL

Releasing the MAN START pushbutton switch or positioning the ENG/MODE selector switch to NORM or IGN/START has no effect on the wet crank status.

NOTE: Due to the ECU reset which is performed when the ENG/MASTER control switch is set from ON to OFF, the starter air valve is commanded closed when going from a wet to dry motor, if engine core speed is above 10% N2. The starter air valve is commanded back open when speed drops below 10% N2.

1 Start ignition
During ground autostart the FADEC selects one igniter only. A second igniter may be turned on for a delayed or no light condition. During a manual start or in-flight autostart the FADEC selects both igniters on simultaneously.

2 Continuous ignition
Manual selection of continuous ignition by the crew is accomplished in the ECU on the ground when the engine is running and if the ENG/MODE selector switch position is cycled from NORM to IGN/START position. In flight, continuous ignition is selected whenever the ENG/MODE selector switch is in IGN/START position (i.e., ENG/MODE selector switch does not need to be cycled).
In addition, automatic selection of continuous ignition by the ECU is accomplished when the engine is running and the ANTI ICE/ENG pushbutton switch is selected ON as indicated by EIU label 030 Bit 14.
In the event of loss of valid EIU label 030 data, the continuous ignition logic defaults to the off selection state unless EIU label 031 data commands continuous ignition. However, in the event of loss of valid EIU label 031 data, automatic selection of continuous ignition is accomplished by the ECU.

(d) Engine flame-out protection
The ECU has the capability to detect an engine flame-out. When a flame-out condition is detected, continuous ignition is automatically selected.
If the ENG/MODE selector switch is in the NORM position and a successful automatic relight is achieved, continuous ignition is discontinued after 30 seconds. This automatic ignition feature aids in the relight of the engine if the ENG/MASTER control switch is inadvertently turned OFF then back ON again.
If the ENG/MODE selector switch is in the IGN/START position with flight/ground status indicating flight, then continuous ignition remains on.
If the ENG/MODE selector switch is in NORM or IGN/START position with flight/ground status indicating ground, continuous ignition is discontinued if the engine drops below the automatic flame-out protection speed of 40% N2. An engine relight following a flame-out is accomplished by manually initiating an engine shutdown, dry cranking and performing either restart procedure.

(e) Engine shutdown
Engine shutdown is primarily controlled by closure of the HPSOV. The HPSOV is operated by a solenoid coil wired directly to the ENG/MASTER control switch.
The ECU has the capability to turn fuel off via the FMV during any of the following conditions:

1 Auto ground starting sequence up to 50% core speed, which includes:

ignition failure with dual igniters
stall (protection up to 8210 RPM core speed).

2 Any ground condition up to 50% core speed in the event EGT exceeds the start overtemperature limit.
In the case where the ENG/MASTER control switch is cycled from ON to OFF, then to ON position, the ECU commands the FMV and the igniters to ON one second after the ENG/MASTER control switch is set back to the ON position as per the engine flame-out protection outlined in paragraph (d). The one-second time delay by the ECU is provided for required HMU hydraulic reset when the HPSOV is closed.

F. Engine Parameters Transmission for Cockpit Display
The FADEC provides the necessary engine parameters for cockpit display through the ARINC 429 buses output (Ref. AMM D/O 73-25-00-00).

G. Engine Condition Parameters Transmission
Engine condition monitoring is possible, by the ability of the FADEC to broadcast the engine parameters through the ARINC 429 bus output.
The basic engine parameters available are:

P0, PS12, PS3, T12, T25, T3, TC, TOIL, T495, N1, N2, WF
VSV, VBV, HPTCC, WF, RACCS, and LPTCC valve or actuator positions
status and maintenance words, engine serial number and position.

In order to perform a better analysis of engine condition some additional parameters are optionally available. These are PS13, P25 and T5.

H. FADEC System Faults Diagnostics

(1) Fault Detection
The FADEC maintenance is made easier by internal extensive Built In Test Equipment allowing efficient fault detection.
The results of this fault detection are contained in status and maintenance words according to ARINC 429 specification and available on the output data bus.

(2) Fault display on the Scheduled Maintenance Report (SMR)
Faults are shown and recorded on the Scheduled Maintenance Report.
They are stored in the EEC memory with the date when the fault occurred for the last time.
A maximum of 12 faults during the last 64 flights legs can be recorded.
Thus, if there are less than 12 faults recorded, the faults recorded before will be available on the Scheduled Maintenance Report during 64 flight legs.
After 64 flight legs, the fault is erased from the EEC memory.
For each fault, there is the date when the fault occurred last:

If the date of the fault is superseded by the date of the last flight leg, the fault is still present.
If the date of the fault is not the same as the date of the last flight leg, the fault is no more present but is available on the Scheduled Maintenance Report during a maximum of 64 flight legs.

(3) Non Volatile Memory
In flight fault data is stored in an engine-provided non volatile memory and when requested available in an aircraft centralized maintenance display unit.

(4) Communication with CFDS
Ground test of electrical and electronic parts is possible from cockpit with engines not running through the CFDS.
The FADEC system provides engine control system self-testing to detect problem at LRU level. The following Table gives the list of LRU's.
FADEC system is such that no engine ground run for trim purposes is necessary after component replacement.

----------------------------------------------------------------

FADEC SYSTEM LRU'S

----------------------------------------------------------------

PUMP ENGINE FUEL PUMP

ECU ELECTRONIC CONTROL UNIT

HMU HYDROMECHANICAL CONTROL UNIT

T12 INLET AIR TEMP. SENSOR

T25 BOOSTER DISCHARGE TEMP. SENSOR

T3 COMPRESSOR EXIT TEMP. SENSOR

T495 EGT SENSOR HARNESS (UPPER, LOWER)

T5 LPT DISCHARGE TEMP. THERMOCOUPLE

N1 FAN SPEED SENSOR

N2 CORE SPEED SENSOR

TCC HPT SHROUD TEMP. SENSOR R, L

T OIL ENGINE OIL TEMP. SENSOR

ALT ENGINE ALTERNATOR STATOR

ALT ENGINE ALTERNATOR ROTOR

STARTER ENGINE AIR STARTER

SAV STARTER AIR VALVE

SERVO HX SERVO FUEL HEATER

OIL HX ENGINE OIL HEAT EXCHANGER

IDG HX IDG OIL/FUEL HEAT EXCHANGER (IDG OIL COOLER)

HPTCC HP TURBINE CLEARANCE CONTROL VALVE

LPTCC LP TURBINE CLEARANCE CONTROL VALVE

RACC ROTOR ACTIVE CLEARANCE CONTROL VALVE

ECU AIR ECU AIR EJECTOR SOLENOID

J5 J5 ENGINE HARNESS

J6 J6 ENGINE HARNESS

J7 J7 ENGINE HARNESS

J8 J8 ENGINE HARNESS

J9 J9 ENGINE HARNESS

J10 J10 ENGINE HARNESS

J11 J11 ENGINE HARNESS

J12 J12 ENGINE HARNESS

J13 J13 ENGINE HARNESS

RATING PLUG ENGINE IDENT, RATING PLUG

IGN ENGINE IGNITOR EXCITER 1, 2

IDG IDG CONTROL VALVES

BSV BURNER STAGING VALVE

FLOW FUEL FLOW METER

VSV COMPRESSOR STATOR VANE ACTUATOR R, L

VBV VARIABLE BLEED MOTOR

VBVF VARIABLE BLEED FEEDBACK

----------------------------------------------------------------

I. ECU Cooling Control
Not Applicable
Not Applicable

** ON A/C NOT FOR ALL

3. Component Description

A. Engine Sensors

(1) T12 Sensor

(a) General
The T12 sensor is made to measure the engine intake air temperature. It is installed on the air inlet cowl at the 1:00 o'clock position.

(b) Description and operation

T12 Temperature Sensor ** ON A/C NOT FOR ALL

The T12 temperature sensor has 2 components: the sensing element and the housing.

1 The sensing element has a reference grade platinum wire bifilar wound on the cylindrical metal mandrel. The mandrel is insulated with a ceramic material prior to the winding of the element. Through the center, 2 large wires run the entire length. These wires are insulated from each other and the mandrel with a ceramic insulator. At one end, the element wires are joined to the wires from the mandrel. The entire element length and lead termination area is then covered with ceramic insulation resulting in a solid construction of alternating insulation and metal to form a uniform cylinder. The element is sealed to protect it from severe environmental conditions by potting the element in a metal cylinder using ceramic as the insulator. Only one end is open to the atmosphere, the connector attachment end. The free ends of the lead-wires are joined to the connector during the final assembly of the element in the airfoil housing. The sensor assembly is inserted into the housing and brazed in place near its open end. To increase its flexibility while minimizing effects on performance, the element is protected by a coaxial perforated shield and is supported at 4 points by annular leaf spring spacers.

2 The housing for the temperature sensing element is made to protect the element and keep vibration to a minimum. The sensing element is located in a slot in the housing and forms a bypass for air flow. Air flowing past the housing changes direction to enter the slot. This prevents foreign objects from entering the slot and damaging the element. It also uses boundary layer control to ensure that the sensed temperature is the free stream temperature rather than that of the boundary layer. The housing is made to minimize turbulence in the gas stream and also to operate over a limited range of angle of attack.

(2) T25 Sensor

(a) General
The T25 sensor is located at 5:45 o'clock upstream of variable bleed (VBV) in fan frame. The sensor measures the air temperature downstream of the booster. This dual sensor is of the resistor probe type (platinum).

(b) Description

T25 Sensor ** ON A/C NOT FOR ALL

The T25 sensor is composed of the following elements:

1 One sensitive tube-shaped part (to be dipped in the engine flow path) composed of the following items:

a One elbow to orientate the airflow onto the sensitive elements of the sensor.

b Five holes located on the trailing edge to prevent dust accumulation in the sensor that could cause airflow modification.

c One slot located on the trailing edge to ensure a regular airflow on the sensitive elements of the sensor.

d One tube with holes placed radially in sensor inlet to avoid vortex.

e Two probes. Each probe has one resistor and its corresponding electrical line.

2 One body composed of the following items:

a One integral metal box that ensures connection between lines and receptacles.

b One flange with 4 captive bolts and a locating pin for sensor attachment to the engine.

c Two receptacles that ensure interface between sensor and HCJ12R harness for channel B and HCJ11R for channel A.

(c) Operation
The operating principle of the sensor is based on the properties inherent to metals (in this case platinum), being that their resistance varies in relation to temperature.
A current generated by the ECU supplied to the probe resistor has its signal modified by the temperature surrounding the probe.

(3) T49-5 Sensor
The T49-5 sensor is described in chapter 77-20-00.

(4) N1 Sensor
The N1 sensor is described in chapter 77-10-00.

(5) N2 Sensor
The N2 sensor is described in chapter 77-10-00.

(6) Oil Temperature Sensor

(a) General
The oil temperature sensor is installed on the No. 1 and 2 bearing oil return tube and is located at 3 o'clock ahead of fan frame, in front of engine mount fitting.
The sensor is a dual type thermocouple (Chromel/Alumel).

(b) Description

Oil Temperature Sensor ** ON A/C NOT FOR ALL

The oil temperature sensor is composed of the following:

A metal body including:
A fixed connector.
A shoulder which ensures seating of tightening nut.
A cylindrical part provided with a groove which accommodates a seal for sensor tightness.
A cylindrical boss in which are inserted the 2 hot junctions of thermocouples.
A nut to secure sensor on oil tube.

Oil Temperature Sensor ** ON A/C NOT FOR ALL

Each thermocouple inserted in the sensor generates an electromotive force proportional to the surrounding temperature (oil temperature) of the hot junctions.
Both signals (channel A and B) are routed to the ECU through the connector and the HJ13 cable.

B. Permanent Magnetic Alternator

(1) General
The control alternator is a high speed bearingless device that generates 3-phase electrical power for use by the engine control system.
The output is sufficient for engine needs above 15% N2.

Permanent Magnetic Alternator ** ON A/C NOT FOR ALL

The alternator is located on the left forward side of the accessory gearbox. It consists of a separate interchangeable rotor and a separate interchangeable stator. The rotor contains permanent magnets and is piloted on the accessory shaft which has 3 equally spaced drive flats. The rotor is retained by a nut. The stator has dual 3-phase windings and is bolted to the accessory pad. Sealing is provided by an O-ring.

C. Electronic Control Unit

Electronic Control Unit ** ON A/C NOT FOR ALL

(1) General
The electronic control unit (ECU) is a dual channel digital electronic control with each channel utilizing a microprocessor for main control functions, a microcontroller for pressure transducer interface functions and a microcontroller for ARINC communication function.
The ECU receives engine inlet condition data from the aircraft Air Data Computers (ADCs) and operational commands from the Engine Interface Unit (EIU) in the aircraft on ARINC 429 data buses. It also receives operating condition data from the various dedicated engine sensors such as T12, PS12, P0, N1, N2, PS3, T25, T3 and TC, and computes the necessary fuel flow, VSV, VBV, HPT clearance control, LPT clearance control, and rotor active clearance control valve positions. The ECU provides the necessary current to the torque motors in the hydromechanical unit to control the various modulating valves and actuators.
The ECU performs On/Off control of the Ignition Relays, Starter Air Valve Solenoid, Aircraft Thrust Reverser Directional Valve and Thrust Reverser Pressurizing Valve.
The ECU provides digital data output in ARINC 429 format to the aircraft for the engine parameter display, aircraft flight management system and the aircraft maintenance data system.
ECU hardware and software is designed so that the two channels operate normally with a set of internal inputs and outputs with access to cross channel data inputs. Each channel can also operate independently without cross channel data.
Fault tolerance enables the engine to continue operation in the event any or all of the airframe digital data is lost.
The ECU is powered by a three-phase engine alternator.
Aircraft power is required up to 15% N2 above which the alternator is able to self-power the unit. Two independent coils from the alternator provide the power to the two separate ECU channels.
The ECU is a vibration isolated single unit mounted on the fan case.

D. Hydromechanical Unit

(1) General
The hydromechanical unit (HMU) is installed on the aft side of the accessory gearbox at the extreme left hand pad. It receives electrical signals from the electronic control unit (ECU) and converts these electrical input signals through torque motors/servo valves into engine fuel flow and hydraulic signals to various external systems. Engine fuel is used as hydraulic medium.

Hydromechanical Unit (Sheet 1 of 4) ** ON A/C NOT FOR ALL

Hydromechanical Unit (Sheet 2 of 4) ** ON A/C NOT FOR ALL

Hydromechanical Unit (Sheet 3 of 4) ** ON A/C NOT FOR ALL

Hydromechanical Unit (Sheet 4 of 4) ** ON A/C NOT FOR ALL

A general schematic of the HMU is shown in the referenced illustration

HMU Block Diagram ** ON A/C NOT FOR ALL

(2) Operation

(a) Fuel metering
The fuel metering valve is hydraulically driven through a torque motor/ servo valve by the ECU. The torque motor contains two electrically isolated, independent coils, one dedicated to Channel A, the other to Channel B of the ECU. A differential pressure regulating valve maintains a constant pressure drop across the metering valve. As a result, fuel flow varies proportionally with metering valve position. Two fuel metering valve position resolvers, one dedicated to each channel in the ECU, produce an electrical feedback signal in proportion to fuel metering valve position. The ECU uses this signal to compute the current required at the fuel metering valve torque motor for achieving closed loop electrical control.

(b) Motive flow modulation
The HMU contains 5 additional torque motors/pilot valves that modulate hydraulic signals to the following:
1 - Low Pressure Turbine Clearance Control Valve
2 - High Pressure Turbine Clearance Control Valve
3 - Rotor Active Clearance Control System
4 - Variable Stator Vane Actuators
5 - Variable Bleed Valve Actuators.
Each torque motor contains two electrically isolated, independent coils.
One is dedicated to channel A, the other to channel B, of the ECU. They provide flow and pressure at an HMU pressure port in response to electrical commands from the ECU.

1 General
The fuel shutoff valve shuts off fuel flow to the engine in response to an aircraft supplied electrical signal. The valve is driven by a solenoid. Valve position is indicated to the ECU by two electrical limit switches.

2 Description

Pressurizing & Shut-off Valve Layout Showing Switch Actuator ** ON A/C NOT FOR ALL

3 Operation
The fuel shut off valve shuts off fuel flow to the engine in response to an aircraft supplied electrical signal commanded by the ENG/MASTER control switch.

Pressurizing & Shut-off Valve Layout Showing Switch Actuator ** ON A/C NOT FOR ALL

The fuel shut off solenoid is energized by aircraft 28VDC from busbar 3PP. It has to be noted that the HP fuel shut off valve shut off signal also closes the LP fuel valve.

Power Supply HP Fuel Shut-off Valve ** ON A/C NOT FOR ALL

The HP fuel shut off valve is open when all three following conditions are met:

command to open from A/C (soleinoid de-energized)
engine rotation speed above 15% N2
fuel flow requested by FADEC unit (FMV > 8 Deg.)

(d) Overspeed governor
The overspeed governor is of the fly ball type. It is designed to prevent the engine from exceeding a steady state speed of 106.3% N2.

E. Electrical Harnesses

(1) General

(a) Two types of harnesses are used depending on where they are installed on the engine.
The harnesses which run along the core engine and the low pressure turbine have a special design to withstand the high temperature near the engine hot sections.
The harnesses which run on the fan inlet case and the fan frame have a more conventional design.
All the harnesses that run on the core engine and the LPT converge to the 6 o'clock tube bundle and harness junction box which provides an interface between the two types of harnesses. All the harnesses are screened against high frequency electrical interferences, and each individual cable within a harness is screened against low frequency electrical interferences.

(b) Low Temperature Harnesses

Electrical Harnesses ** ON A/C NOT FOR ALL

The low temperature harness consists in screened and sheathed American Wire Gauge 20 cables with two cores (copper or chromel/alumel) that are enclosed in a polyamide braid for insulation and protection against rubbing by the shielding braid. The HF shielding is provided by a tined copper braid which is surrounded by a heat shrinkable tubing to protect the copper braid and to ensure the wire strand sealing.

Electrical Harnesses ** ON A/C NOT FOR ALL

The high temperature harness consists in screened and sheathed American Wire Gauge 20 cables with two cores (copper or chromel/alumel) that are enclosed in a convoluted PTFE (teflon) conduit for insulation and protection against rubbing by the shielding braid.
When there are not enough cables to fill the PTFE conduit, silicone tubes are added to cables.
The HF shielding is provided by a stainless steel braid. It is surrounded by a polyamide braid that is coated with Viton material for insulation and protection against possible barbs of the steel braid. The polyamide braid is not used when the harness runs close to a very hot part of the engine (combustion chamber, turbine section).

(d) Low Temperature Connectors

Electrical Connectors ** ON A/C NOT FOR ALL

In the engine cold section, stainless steel, fluid-proof connectors are used. They are made of two types, depending on the number of wires the harness contains.
If there is a single strand, the HF shielding braid is directly clamped on the connector adapter.
If there are several strands, the HF shielding braids are first crimped together with a main HF shielding braid, and then clamped on the connector adapter. The adapter is bolted on the electrical plug, and the junction is protected by a heat shrinkable sleeve bonded and clamped on the connector adapter.
A potting port allows the injection of a compound inside the sleeve to ensure connector sealing.

(e) High Temperature Connector

Electrical Connectors ** ON A/C NOT FOR ALL

The high temperature connector adapter has two clamping areas. The external polyamide braid and the PTFE conduit are clamped on the first one.
The stainless steel shielding braid is clamped on the second one. The connector adapter is bolted on the electrical plug, and sealing is provided by the clamping of the PTFE conduit.

(f) Harness J7

PRE SB CFM 72-519

Electrical Harness J7 - PRE SB CFM 72-519 ** ON A/C NOT FOR ALL

POST SB CFM 72-519

Electrical Harness J7 - POST SB CFM 72-519 ** ON A/C NOT FOR ALL

END OF SB CFM 72-519

1 Transmits the signals (Channels A) from the engine control unit (ECU) to the following components/accessories:

a Fuel metering valve position transmitter, located in the hydromechanical unit (HMU).

b Fuel metering valve actuating torque motor in the HMU.

c Fuel shutoff valve closed position switch in the HMU.

d Variable Stator Vane (VSV) actuator controlling torque motor in the HMU.

e High Pressure Turbine Clearance Control (HPTCC) actuator controlling torque motor in the HMU.

f Variable Bleed Valve (VBV) hydraulic motor controlling torque motor in the HMU.

g Burning stage valve (one fuel nozzle out of 2) in the HMU.

h Rotor Active Clearance Control (RACC) actuator controlling torque motor in the HMU.

i Low Pressure Turbine Clearance Control (LPTCC) actuator controlling torque motor in the HMU.

j Compact Constant Frequency Generator (CCFG) cooling fuel return to A/C tank shutoff solenoid.

PRE SB CFM 72-519

k Shutoff solenoid for (air) cooling of ECU.

POST SB CFM 72-519

l Not applicable

END OF SB CFM 72-519

2 Transmits to the ECU the signals (Channels A) that come from the following components/accessories:

a Fuel metering valve position transmitter in HMU.

b Fuel shutoff valve closed position switch in HMU.

c N2 speed sensor.

3 Transmits, from the HMU to the ECU, the overspeed signal sensed by the overspeed governor (OSG).

NOTE: This same line provides electrical supply to the overspeed governor.

4 The harness consists of:

PRE SB CFM 72-519

a Five connectors.

b Four cables.

POST SB CFM 72-519

c Four connectors.

d Three cables.

END OF SB CFM 72-519

e One tubular junction box (in stainless steel) with 2 attachment lugs.

f One T-shaped derivation with heat-shrinkable covering.

(g) Harness J8

PRE SB CFM 72-519

Electrical Harness J8 - PRE SB CFM 72-519 ** ON A/C NOT FOR ALL

POST SB CFM 72-519

Electrical Harness J8 - POST SB CFM 72-519 ** ON A/C NOT FOR ALL

END OF SB CFM 72-519

1 Transmits the signals (Channels B) from the ECU to the following components/accessories:

a Fuel metering valve position transmitter in HMU.

b Fuel metering valve actuating torque motor in HMU.

c Fuel shutoff valve closed position switch in HMU.

d VSV actuator controlling torque motor in HMU.

e HPTCC actuator controlling torque motor in HMU.

f VBV hydraulic motor controlling torque motor in HMU.

g Burning stage valve in HMU.

h RACC actuator controlling torque motor in HMU.

i LPTCC actuator controlling torque motor in HMU.

j CCFG cooling fuel return to A/C tank shutoff solenoid.

PRE SB CFM 72-519

k Shutoff solenoid for (air) cooling of ECU.

POST SB CFM 72-519

l Not applicable

END OF SB CFM 72-519

2 Transmits to the ECU the signals (Channels B) from the following components/accessories:

a Fuel metering valve position transmitter in HMU.

b Fuel shutoff valve closed position switch in HMU.

c N2 speed sensor.

3 Transmits, from the HMU to the ECU, the signal from the fuel temperature sensor (chromel/alumel thermocouple probe).

4 The harness consists of:

PRE SB CFM 72-519

a Five connectors.

b Four cables.

POST SB CFM 72-519

c Four connectors.

d Three cables.

END OF SB CFM 72-519

e One tubular junction box (in stainless steel) with 2 attachment lugs.

f One T-shaped derivation with heat-shrinkable covering.

(h) Harness J9

Electrical Harness J9 ** ON A/C NOT FOR ALL

1 Transmits to the ECU the signals (Channels A) from the following components/accessories:

a Alternator (ECU power supply).

b Starting valve position sensor.

c T12 temperature sensor.

d N1 speed sensor.

2 Transmits the signals (Channels A) from the ECU to the following components/accessories:

a Starting valve position sensor (supply).

b Starter (air) shutoff solenoid valve.

3 The harness consists of:

a Five connectors.

b Four cables.

c Two T-shaped derivations with heat-shrinkable covering.

d One Y-shaped derivation with heat-shrinkable covering.

(i) Harness J10

Electrical Harness J10 ** ON A/C NOT FOR ALL

1 Transmits to the ECU the signals (Channels B) from the following components/accessories:

a Alternator (ECU power supply).

b Starting valve position sensor.

c T12 temperature sensor.

d N1 speed sensor.

2 Transmits the signals (Channels B) from the ECU to the following components/accessories:

a Starting valve position sensor (supply).

b Starter (air) shutoff solenoid valve.

3 The harness consists of:

a Five connectors.

b Four cables.

c Three T-shaped derivations with heat-shrinkable covering.

(j) Harness J11

Electrical Harness J11 ** ON A/C NOT FOR ALL

Provides the interface, between the 6 o'clock box and the ECU, of the following harnesses:

1 Harness CJ11R.

2 Harness CJ11L.

3 The harness consists of:

a Three connectors.

b Two cables.

c One Y-shaped derivation with heat-shrinkable covering.

(k) Harness J12

Electrical Harness J12 ** ON A/C NOT FOR ALL

Provides the interface, between the 6 o'clock box and the ECU, of the following harnesses:

1 Harness CJ12R.

2 Harness CJ12L.

3 The harness consists of:

a Three connectors.

b Two cables.

c One Y-shaped derivation with heat-shrinkable covering.

(l) Harness J13

Electrical Harness J13 ** ON A/C NOT FOR ALL

1 Provides the interface of harness CJ13 between the 6 o'clock box and the ECU.

2 Transmits to the ECU the signals from the oil temperature sensor (2 chromel/alumel thermocouples generating 2 signals: A and B).

3 Transmits the signals (2) from the fuel flowmeter, to the ECU.

NOTE: These signals are not processed by the ECU for integration in the engine electronic control loop. They are used only for fuel flow indication purposes on the engine instrumentation panel in the aircraft cockpit.

4 The harness consists of:

a Three connectors.

b One receptacle fitted with a 2-hole flange for attachment to the 6 o'clock box.

c Three cables (of which 2 consist of chromel and alumel wires).

d Two Y-shaped derivations with heat-shrinkable covering.

(m) Harness CJ11L

Electrical Harness CJ11L ** ON A/C NOT FOR ALL

1 Transmits the electrical power supply (from the box at 6 o'clock) to the following components/accessories:

a Variable Bleed Valve (VBV) position sensor (Channel A).

b Burning Stage Valve (BSV) pressure switch (Channel A).

2 Transmits the signals from the VBV position sensor to the box at 6 o'clock.

3 The harness consists of:

a Two connectors.

b One receptacle.

c Two cables.

d One junction box made of steel.

(n) Harness CJ11R

Electrical Harness CJ11R ** ON A/C NOT FOR ALL

1 Transmits the electrical power supply to following components/accessories:

a Variable Stator Vane (VSV) position sensor (Channel A).

b Low Pressure Turbine Clearance Control (LPTCC) valve position sensor (Channel A).

c High Pressure Turbine Clearance Control (HPTCC) valve position sensor (Channel A).

PRE SB CFM56-5 75-031

d Rotor Active Clearance Control (RACC) valve position sensor (Channel A).

POST SB CFM56-5 75-031

e Not applicable.
END OF SB CFM56-5 75-031

f T25 temperature sensor (Channel A).

2 Transmits the signals from the above sensors to the box at 6 o'clock.

3 The harness consists of:

PRE SB CFM56-5 75-031

a Five connectors.

b Five cables.

POST SB CFM56-5 75-031

c Four connectors.

d Four cables.
END OF SB CFM56-5 75-031

e Two metallic junction boxes.

f One connection box including:
One flange for attachment to the 6 o'clock box.
One receptacle.

(o) Harness CJ12L

Electrical Harness CJ12L ** ON A/C NOT FOR ALL

1 Transmits (from the box at 6 o'clock) the electrical power supply to the following components/accessories:

a VSV position sensor (Channel B).

b VBV position sensor (Channel B).

c BSV pressure switch (Channel B).

2 Transmits the signals from the above sensors and switch to the box at 6 o'clock.

3 The harness consists of:

a Three connectors.

4 One receptacle.

5 Three cables.

6 Two junction boxes of rigid construction.

(p) Harness CJ12R

Electrical Harness CJ12R ** ON A/C NOT FOR ALL

1 Transmits (from the box at 6 o'clock) the electrical power supply to the following components/accessories:

a LPT Clearance Control (LPTCC) valve position sensor (Channel B).

b HPT Clearance Control (HPTCC) valve position sensor (Channel B).

PRE SB CFM56-5 75-031

c Rotor Active Clearance Control (RACC) valve position sensor (Channel B).

POST SB CFM56-5 75-031

d Not applicable.
END OF SB CFM56-5 75-031

e T25 temperature sensor (Channel B).

2 Transmits the signals that come from the above sensors to the box at 6 o'clock.

3 The harness consists of:

PRE SB CFM56-5 75-031

a Four connectors.

b Four cables.

POST SB CFM56-5 75-031

c Three connectors.

d Three cables.
END OF SB CFM56-5 75-031

e One metallic connection box including:

One receptacle.
One flange with holes for attachment to the 6 o'clock box.

f One junction box including:

One metallic body.
Two attachment lugs.

(q) Harness CJ13

Electrical Harness CJ13 ** ON A/C NOT FOR ALL

1 Transmits to the 6 o'clock box the signals that come from the following thermocouple probes:

a Nine T495 temperature probes (averaged in the T495 thermocouple harness).

b Two T3 temperature sensors (Channels A and B).

c One T5 temperature sensor.

d One HPT case temperature sensor.

2 The harness consists of:

a Seven connectors.

b Six cables.

c Four junction boxes composed of the following:

Two cylindrical metal boxes each with one lug for attachment to the engine.
One tubular metal box with two attachment lugs.
One rectangular metal box with 2 holes for attachment to the engine with 2 bolts.

NOTE: All the lines composing the cables of this harness are chromel and alumel wires.

(2) General

(b) Low Temperature Harnesses

Electrical Harnesses ** ON A/C NOT FOR ALL

(d) Low Temperature Connectors

Electrical Connectors ** ON A/C NOT FOR ALL

(e) High Temperature Connector

Electrical Connectors ** ON A/C NOT FOR ALL

(f) Harness J7

Electrical Harness J7 - PRE SB CFM 72-519 ** ON A/C NOT FOR ALL

Electrical Harness J7 - POST SB CFM 72-519 ** ON A/C NOT FOR ALL

1 Transmits the signals (Channels A) from the engine control unit (ECU) to the following components/accessories:

a Fuel metering valve position transmitter, located in the hydromechanical unit (HMU).

b Fuel metering valve actuating torque motor in the HMU.

c Fuel shutoff valve closed position switch in the HMU.

d Variable Stator Vane (VSV) actuator controlling torque motor in the HMU.

e High Pressure Turbine Clearance Control (HPTCC) actuator controlling torque motor in the HMU.

f Variable Bleed Valve (VBV) hydraulic motor controlling torque motor in the HMU.

g Burning stage valve (one fuel nozzle out of 2) in the HMU.

h Rotor Active Clearance Control (RACC) actuator controlling torque motor in the HMU.

i Low Pressure Turbine Clearance Control (LPTCC) actuator controlling torque motor in the HMU.

j Compact Constant Frequency Generator (CCFG) cooling fuel return to A/C tank shutoff solenoid.

k Shutoff solenoid for (air) cooling of ECU.

2 Transmits to the ECU the signals (Channels A) from the following components/accessories:

a Fuel metering valve position transmitter in HMU.

b Fuel shutoff valve closed position switch in HMU.

c N2 speed sensor.

3 Transmits, from the HMU to the ECU, the overspeed signal sensed by the overspeed governor (OSG).

NOTE: This same line provides electrical supply to the overspeed governor.

4 The harness consists of:

a Five connectors.

b Four cables.

c One tubular junction box (in stainless steel) with 2 attachment lugs.

d One T-shaped derivation with heat-shrinkable covering.

(g) Harness J8

Electrical Harness J8 - PRE SB CFM 72-519 ** ON A/C NOT FOR ALL

Electrical Harness J8 - POST SB CFM 72-519 ** ON A/C NOT FOR ALL

1 Transmits the signals (Channels B) from the ECU to the following components/accessories:

a Fuel metering valve position transmitter in HMU.

b Fuel metering valve actuating torque motor in HMU.

c Fuel shutoff valve closed position switch in HMU.

d VSV actuator controlling torque motor in HMU.

e HPTCC actuator controlling torque motor in HMU.

f VBV hydraulic motor controlling torque motor in HMU.

g Burning stage valve in HMU.

h RACC actuator controlling torque motor in HMU.

i LPTCC actuator controlling torque motor in HMU.

j CCFG cooling fuel return to A/C tank shutoff solenoid.

k Shutoff solenoid for (air) cooling of ECU.

2 Transmits to the ECU the signals (Channels B) from the following components/accessories:

a Fuel metering valve position transmitter in HMU.

b Fuel shutoff valve closed position switch in HMU.

c N2 speed sensor.

3 Transmits, from the HMU to the ECU, the signal that comes from the fuel temperature sensor (chromel/alumel thermocouple probe).

4 The harness consists of:

a Five connectors.

b Four cables.

c One tubular junction box (in stainless steel) with 2 attachment lugs.

d One T-shaped derivation with heat-shrinkable covering.

(h) Harness J9

Electrical Harness J9 ** ON A/C NOT FOR ALL

1 Transmits to the ECU the signals (Channels A) from the following components/accessories:

a Alternator (ECU power supply).

b Starting valve position sensor.

c T12 temperature sensor.

d N1 speed sensor.

2 Transmits the signals (Channels A) from the ECU to the following components/accessories:

a Starting valve position sensor (supply).

b Starter (air) shutoff solenoid valve.

3 The harness consists of:

a Five connectors.

b Four cables.

c Two T-shaped derivations with heat-shrinkable covering.

d One Y-shaped derivation with heat-shrinkable covering.

(i) Harness J10

Electrical Harness J10 ** ON A/C NOT FOR ALL

1 Transmits to the ECU the signals (Channels B) from the following components/accessories:

a Alternator (ECU power supply).

b Starting valve position sensor.

c T12 temperature sensor.

d N1 speed sensor.

2 Transmits the signals (Channels B) from the ECU to the following components/accessories:

a Starting valve position sensor (supply).

b Starter (air) shutoff solenoid valve.

3 The harness consists of:

a Five connectors.

b Four cables.

c Three T-shaped derivations with heat-shrinkable covering.

(j) Harness J11

Electrical Harness J11 ** ON A/C NOT FOR ALL

Provides the interface, between the 6 o'clock box and the ECU, of the following harnesses:

1 Harness CJ11R.

2 Harness CJ11L.

3 The harness consists of:

a Three connectors.

b Two cables.

c One Y-shaped derivation with heat-shrinkable covering.

(k) Harness J12

Electrical Harness J12 ** ON A/C NOT FOR ALL

Provides the interface, between the 6 o'clock box and the ECU, of the following harnesses:

1 Harness CJ12R.

2 Harness CJ12L.

3 The harness consists of:

a Three connectors.

b Two cables.

c One Y-shaped derivation with heat-shrinkable covering.

(l) Harness J13

Electrical Harness J13 ** ON A/C NOT FOR ALL

1 Provides the interface of harness CJ13 between the 6 o'clock box and the ECU.

2 Transmits to the ECU the signals from the oil temperature sensor (2 chromel/alumel thermocouples generating 2 signals: A and B).

3 Transmits the signals (2) that come from the fuel flowmeter, to the ECU.

4 The harness consists of:

a Three connectors.

b One receptacle fitted with a 2-hole flange for attachment to the 6 o'clock box.

c Three cables (of which 2 consist of chromel and alumel wires).

d Two Y-shaped derivations with heat-shrinkable covering.

(m) Harness J15

Electrical Harness J15 ** ON A/C NOT FOR ALL

1 Provides the interface between the ECU and the bleed bias transducer.

2 The harness consists of:

a Three connectors.

b Two cables.

c One Y-shaped derivation with heat-shrinkable covering.

(n) Harness CJ11L

Electrical Harness CJ11L ** ON A/C NOT FOR ALL

1 Transmits the electrical power supply (from the box at 6 o'clock) to the following components/accessories:

a Variable Bleed Valve (VBV) position sensor (Channel A).

b Burning Stage Valve (BSV) pressure switch (Channel A).

2 Transmits the signals from the VBV position sensor to the box at 6 o'clock.

3 The harness consists of:

a Two connectors.

b One receptacle.

c Two cables.

d One junction box made of steel.

(o) Harness CJ11R

Electrical Harness CJ11R ** ON A/C NOT FOR ALL

1 Transmits the electrical power supply to following components/accessories:

a Variable Stator Vane (VSV) position sensor (Channel A).

b Low Pressure Turbine Clearance Control (LPTCC) valve position sensor (Channel A).

c High Pressure Turbine Clearance Control (HPTCC) valve position sensor (Channel A).

PRE SB CFM56-5 75-031

d Rotor Active Clearance Control (RACC) valve position sensor (Channel A).

POST SB CFM56-5 75-031

e Not applicable.
END OF SB CFM56-5 75-031

f T25 temperature sensor (Channel A).

2 Transmits the signals from the above sensors to the box at 6 o'clock.

3 The harness consists of:

PRE SB CFM56-5 75-031

a Five connectors.

b Five cables.

POST SB CFM56-5 75-031

c Four connectors.

d Four cables.
END OF SB CFM56-5 75-031

e Two metallic junction boxes.

f One connection box including:
One flange for attachment to the 6 o'clock box.
One receptacle.

(p) Harness CJ12L

Electrical Harness CJ12L ** ON A/C NOT FOR ALL

1 Transmits (from the box at 6 o'clock) the electrical power supply to the following components/accessories:

a VSV position sensor (Channel B).

b VBV position sensor (Channel B).

c BSV pressure switch (Channel B).

2 Transmits the signals from the above sensors and switches to the box at 6 o'clock.

3 The harness consists of:

a Three connectors.

4 One receptacle.

5 Three cables.

6 Two junction boxes of rigid construction.

(q) Harness CJ12R

Electrical Harness CJ12R ** ON A/C NOT FOR ALL

1 Transmits (from the box at 6 o'clock) the electrical power supply to the following components/accessories:

a LPT Clearance Control (LPTCC) valve position sensor (Channel B).

b HPT Clearance Control (HPTCC) valve position sensor (Channel B).

PRE SB CFM56-5 75-031

c Rotor Active Clearance Control (RACC) valve position sensor (Channel B).

POST SB CFM56-5 75-031

d Not applicable.
END OF SB CFM56-5 75-031

e T25 temperature sensor (Channel B).

2 Transmits the signals from the above sensors to the box at 6 o'clock.

3 The harness consists of:

PRE SB CFM56-5 75-031

a Four connectors.

b Four cables.

POST SB CFM56-5 75-031

c Three connectors.

d Three cables.
END OF SB CFM56-5 75-031

e One metallic connection box including:

One receptacle.
One flange with holes for attachment to the 6 o'clock box.

f One junction box including:

One metallic body.
Two attachment lugs.

(r) Harness CJ13

Electrical Harness CJ13 ** ON A/C NOT FOR ALL

1 Transmits to the 6 o'clock box the signals from the following thermocouple probes:

a Nine T495 temperature probes (averaged in the T495 thermocouple harness).

b Two T3 temperature sensors (Channels A and B).

c One T5 temperature sensor.

d One HPT case temperature sensor.

2 The harness consists of:

a Seven connectors.

b Six cables.

c Four junction boxes composed of the following:

Two cylindrical metal boxes each with one lug for attachment to the engine.
One tubular metal box with two attachment lugs.
One rectangular metal box with 2 holes for attachment to the engine with 2 bolts.

NOTE: All the lines composing the cables of this harness are chromel and alumel wires.

F. Identification Connector

(1) General
The mobile connector transmits the following electric coded signals to the Electronic Control Unit (ECU):

Engine serial number
Engine family
Engine bump rating
It is coded in the factory during installation of new engine, and is inseparable from the engine. It is connected to the J14 ECU fixed connector.

(2) Description

Identification connector ** ON A/C NOT FOR ALL

This connector consists of a certain number of inseparable parts that cannot be disassembled, comprising the following:

A mobile connector incorporating the following items:
31 sockets (21 active).
A knurled portion to tighten the connector.
a rear body incorporating the identification circuit connected to it.
A metallic braid connected as follows:
Riveted on the rear end of connector.
Screwed and lead sealed to the engine.

(3) Operation
The connector permits or stops the currents generated by the ECU between the different connector contacts. The resulting signals are decoded by the ECU.

G. Ignition Boxes
They are powered with A/C 115VAC through the EIU and FADEC. One of the igniters is powered from a normal bus-bar, the other one from an emergency/ battery busbar.
The FADEC controls the power supply to the ignition boxes, by means of a switch on each of the ignition power supply lines.

H. Starter Air Valve
The FADEC controls the opening and closing of the starter valve and receives the open/not open signal of the valve.

I. Burner Staging Valve
The FADEC controls the opening and closing of the burner staging valve and receives the open signal from the valve.

J. ECU Cooling Feature
This is described in chapter 75-00-00.

K. Thrust Reverser Valve Actuation
This is described in chapter 73-25-00.

L. VSV Feedback Signal
The FADEC receives a VSV position signal feedback from the VSV actuator which is described in chapter 75-30-00.

M. VBV Feedback Signal
Same as VSV feedback signal.

N. HPTCC Feedback Signal
Same as VSV feedback signal.

O. RACCS Feedback Signal
Same as VSV feedback signal.

P. LPTCC Feedback Signal
Same as VSV feedback signal.

[Rev.10 from 2021] 2026.04.01 07:15:41 UTC