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 ECU and the following peripherals.

Hydromechanical Unit
Dedicated Permanent Magnet Alternator
VSV and VBV, HPTACC, LPTACC, RAC/SB systems
Start system (starter shutoff valve, ignition exciters)
Thrust reverser System
Oil/Fuel Temperature Control (IDG oil)
Engine sensors
Electrical harnesses
The ECU is a vibration-isolated single unit mounted on the fan case, air cooled by ducting ambient air to the ECU. It is a part of the basic engine equipment.

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2. System Description

A. Full Authority Digital Engine Control (FADEC)

(1) FADEC Functions

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

for general FADEC system schematic
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 term of fan speed (N1) and core speed (N2) to prevent exceedance of certified red lines
Engine turbine exhaust gas temperature monitoring (EGT).

Automatic engine thrust rating control using N1 as the thrust setting parameter.
Thrust parameter limits computation
Manual power management through constant ratings versus throttle lever relationship :
take-off/go-around at full forward throttle control lever position
flex take-off at constant intermediate position whatever the reduced thrust is, and 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 of 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
IDLE setting 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 (optional)

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

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

Engine oil temperature
Aircraft fuel system configuration
Flight phases.

(2) Hydromechanical Unit

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

The hydromechanical unit (HMU) is attached to the aft section of the fuel pump unit housing. The HMU fuel pump package is installed on the aft side of the AGB, at the left side of the horizontal drive shaft housing. The HMU receives electrical signals from the engine electronic control unit (ECU) and converts these electrical input signals through torque motors/servo valves into the engine fuel flow and hydraulic signals to various external systems. Engine fuel is the hydraulic media.

(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 ECU to hold the requested N1 as limited by : N2, PS3, WF, WF/PS3, 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. PS3 schedule .......... N1 and N2 float

(b) Limitation description

Maximum and minimum N2 schedules.
The ECU sets the fuel to hold the N1 provided 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/PS3.
The ECU sets the fuel to reach the N1 provided WF/PS3 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 ECU. The steady state VSV schedules are more open that in transient and altitude bias allows different altitude schedules.

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

The ECU 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 ECU.
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) Transient Bleed Valve (TBV) Control
The TBV function is to improve the stall margin of the HP Compressor during engine starting and acceleration through the Start Bleed System.
The TBV position is controlled by the ECU, working through the HMU, as a function of the following parameters: N2K25 (corrected core speed), N2 (physical core speed), N2 switched accel, N2 min.
The ECU logic calculates the bleed air to unload the HPC 9th stage to give the optimum stability for transient mode operation. The 9th stage bleed air is sent to the Low Pressure Turbine Nozzle first stage providing an efficient start stall margin.
A feedback valve position is used by the ECU to indicate the TBV position.

(5) High Pressure Turbine Clearance Control (HPTCC)
The HPTCC valve modulates air from the 4th and 9th stages to the turbine shroud.
The ECU controls the valve position. A feedback signal is used by the ECU 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 ECU controls the valve position. A feedback signal is used by the ECU to indicate the valve position to the desired value.

(7) Oil/Fuel Temperature Control
The IDG oil is cooled by engine fuel through an oil/fuel heat exchanger (IDG oil cooler). For some aircraft operation, extra heat rejected in fuel is carried out of the engine fuel system through the 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).
ECU performs this temperature control using the engine oil temperature. ECU has two actions depending upon 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 decrease the 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 flows back to tank controlled by the ECU.
The ECU logic is based on engine oil temperature which is correlated with IDG oil temperature. Each level of flow is corresponding to a level of IDG oil temperature (Ref. AMM D/O 73-10-00-00).
A "close" command from the HMU (master lever OFF) interrupts fuel return flow 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
when FADEC receives an aircraft discrete inhibition signal from the fuel system (through the EIU).
when the engine is shutdown (N2 below 50 percent)
when fuel flow to the burner is above 5520 pph
FADEC automatically increases the engine idle speed when the engine oil temperature is above limit allowing to decrease the cooling fuel flow temperature.
Excessive engine oil temperature is warned to the cockpit by an ARINC word.

C. Engine Limits Protection

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

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

The ECU monitors EGT and sends an appropriate message to the cockpit display in case of abnormally high EGT.
The ECU also provides Max. PS3 protection through the fuel control limitations (Ref. Para. 2.B.).
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 located in HMU.

The electrical governors operate with the engine control laws or the fuel metering valve to limit rotors speed to red line value.
Each channel receives its dedicated N1 and N2 speed signal, but can operate with cross-channel data. The governors operate valid signal only.
Although aerodynamically limited, N1 is also protected by a VSV failure closure when N1 reaches an overspeed. This limits the energy to the LP rotor and limits its maximum speed to a lower aerodynamic value.

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

D. Power Management

(1) Rating Control

(a) The ECU integrates all the engine thrust setting curves to provide automatic engine thrust ratings control.
The ECU 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.
The implementation is done by controlling the corrected Fan speed which correlates closely with thrust at given Mach number and altitude.
For all ratings (take-off, max continuous and max climb ratings), the ECU controls the FAN speed corrected to total temperature. That corrected fan speed is a function of:

ambient static pressure PO for altitude effect.
delta ambient temperature delta TO for temperature effect
mach number
ECS bleed and anti-ice bleed are also taken into account by the ECU 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 intent is to keep the same EGT with and without ECS bleed.
Anti-icing bleeds are taken into account by a delta ambient temperature 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 ECU will identify the rating available.
The ECU will have memory provisions for several different engine ratings.

(b) Flex Take-off
FLEXIBLE TAKE-OFF rating is set by the assumed temperature method with the possibility to insert any assumed temperature value higher than the maximum one certified for engine operation to provide for the maximum derating allowed by the certifying Authorities. The purpose is to obtain reduced thrust operation.
FADEC permits:
Flexible take-off procedure with constant retarded throttle lever position, allowing the application of full take-off power when 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 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
Maintaining 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

Reverser Switches ** ON A/C NOT FOR ALL

The FADEC controls the engine thrust rating during reverser operation. Engine power is set automatically by the ECU to the level required for correct deploy and stow operations in all ambient conditions.
The maximum reverse rating power is automatically controlled by the ECU versus all ambient conditions, with a unique maximum reverse throttle position.
In normal operation, the ECU 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 depending on throttles levers position and upon the autothrust activation/deactivation logic.
Throttles move over a sector divided in 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 are 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 pushbutton switch located on the flight control unit (FCU).
The ATHR de-activation and ATHR disengagement are achieved by action on the disconnect pushbutton switch located on the throttle control levers or by pressing the ATHR pushbutton switch 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 control lever forward of the MCT gate leads to ATHR deactivation but maintains ATHR engaged ; the thrust is controlled by the throttle control lever position and ATHR will be activated again as soon as both throttle control levers are set at or below MCT gate.
If the Alpha Floor condition is present, the ATHR function can be activated regardless of throttle control lever position.
When ATHR is deactivated (FMGC command or failure), the thrust is frozen to the actual value at the time of the deactivation. The thrust will be tied to the throttle control lever position as soon as the throttle control levers have been set out of the MCT or MCL positions.
The ATHR is active if:
TLA < MCT (or TLA = MCT and FLEXTO mode not selected) or Alpha Floor condition and

FCU discretes set to 1
ATHR active = 1
ATHR engaged = 1
Deactivation condition is not present.

1 When the ATHR function is deactived, it may lead either to freeze the thrust to the N1 actual (memo mode) or to recover the manual thrust (manual mode) as shown on figure

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

(d) Alternate Autothrust Deactivation logic
The purpose of this logic is to distinguish a voluntary (pilot initiated) autothrust disconnection versus an inadvertent autothrust disconnection due to a FMGC failure. This logic as well as that specified in paragraph (3) resides in the ECU. The ECU shall utilize this alternate logic if the EIU transmitted label 034 bit 15 is true (this bit is generated by the FMGC).
When selected, this logic shall recover the manual thrust control mode when the ECU receives either a voluntary autothrust disconnection (defined as EIU label 034 bit 16 set to 1, bit computed by the FMGC) or an instinctive disconnection signal from the cockpit pushbutton switches. In the case of inadvertent autothrust disconnection (i.e. label 034 bit 16=0) the ECU will enter the memo thrust mode or manual mode as described in paragraph (c).

(e) 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 control lever angle versus rated thrust relationship is as shown on Figure

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

A forward action on the throttle control lever will not lead to a decrease in thrust. A rearward action on the throttle control lever will 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 control lever position (except in Alpha-floor mode).
Other ratings (MAX CONTINUOUS, MAX CLIMB, IDLE, MAX REVERSE) are achieved at constant throttle control lever positions.
FLEXIBLE TAKE-OFF for a given derating is achieved at constant retarded throttle control lever position.

2 Thrust Limit mode selection
Throttle control lever is used as a rating mode selection device. Based on the throttle control lever position signal, FADEC 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 control lever to the corresponding unique position.

Throttle Lever Definition ** 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 control lever is positioned between two unique positions, the FADEC will select the limit of the higher mode for display

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

When both throttle control lever positions select two different modes the rating limits sent by the two FADEC will be different. The AFS will take into account the highest one.
On ground, as soon as the FADEC is powered ON (engine not running), the computed thrust limit parameter values related to the throttle control lever position are shown on the ECAM upper display unit (Including Flex Take-off Configuration).
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 CDU of the FMS and has been validated (range, parity, SSM tests ...) and is higher than the static air temp., the FADEC Unit 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 control lever 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 control lever is lower than or equal to MCT.
When the engine is running, by setting the throttle control lever above MCL, the value of FLEX temperature is latched in the FADEC 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 control 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 control 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 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 control 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 control lever position through N1CMD = f (TLA).

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

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

(f) 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 will be always limited by the N1 throttle (upper limit) except in alpha floor condition.

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 control levers.

3 Memo Thrust Setting
When ATHR is deactivated, the thrust can be frozen to the actual value (see para Thrust Setting); in this case the thrust is set accordingly to a logic shown on the referenced illustrations.

E. Engine Starting/Ignition Control

Engine Panels ** ON A/C NOT FOR ALL

(1) General
There are two modes of starting control associated with two different procedures and corresponding to two engine starting logics in the ECU

(a) Automatic starting logic under the full authority of the FADEC system.
The FADEC initiates the automatic sequence of command to:

starter air valve opening and closing
HP fuel valve
ignition exciters

The FADEC provides:

engine limits protection N1, N2, EGT
on ground start abort in case of detected incident (hot start, stall, failure to light, hung start, starter time exceedance)
in flight start, only fault announcement, without automatic start abort
specific fault message transmission.

(b) Alternate starting logic with authority of the FADEC limited to :

actuation of starter air valve upon manual cockpit actions on MAN START pushbutton switch and by selection on IGN/START position of the selector switch on ENG panel
ignition exciter energization and HP fuel shut-off valve upon manual setting of ENG MASTER switch to ON
cancellation of ignition and starter air valve is automatically done by the FADEC
warning indications are also provided
passive survey of engine is provided during start without authority to abort it, exception case of EGT overlimit below 50 percent N2 on ground (start abort).
Other FADEC functions are associated to the starting function such as engine cranking, flame out detection and continuous ignition selection.

(2) Automatic Start

(a) Engine starting logic
The FADEC has the capability to perform starting of the engine, including protection of the engine during the starting phase with the necessary indication to the cockpit.
The FADEC operates with the following sequence :

the selector being to ignition position, the FADEC opens the starter air valve when the ENG MASTER switch is switched to ON
when N2 reaches 16 percent rpm the FADEC switches the exciter ON
at N2 = 22 percent rpm the FADEC opens the fuel shut-off valve
at N2 = 50 percent rpm the FADEC closes the starter air valve and de-energizes the ignition exciter
then the FADEC controls the fuel according to the start fuel schedule
in case of ignition delay, the FADEC will automatically operate both ignition exciters after an automatic dry motoring sequence and will provide information to DMC
for airstart FADEC identifies windmilling or starter assist conditions
in case of failure of automatic starter valve actuation device, the FADEC logic is compatible with manual actuation of the start valve.

(b) Start interruption
Interruption of automatic start is possible by selection of the ENG MASTER switch to the OFF position.
That action initiates :

direct closure of the HP fuel shut off valve
starter shutoff valve closure via FADEC
ignition exciters OFF.

1 On ground
Start abort by the FADEC is automatic below 50 percent N2 in case of detected incident such as :

hot start
no ignition
start stall.
starter time exceedance
The FADEC also provides the necessary information to the cockpit.

2 In flight
The FADEC provides the same monitor as on ground with fault announcement but the start abort is manual only.

(3) Alternative Start

(a) Engine starting logic
The FADEC has the capability to perform alternative start, after reception of the signal "Man start".
The FADEC operates with the following sequence :

the ENG/MODE selector switch being to IGN/START position, the FADEC opens the starter shut-off valve when it receives the "Man start" signal
when the ENG MASTER switch is switched to ON, the FADEC opens the HP fuel shut-off valve and energizes the ignition exciter.
when N2 reaches 50 percent rpm the FADEC closes the starter shut-off valve and de-energizes the ignition exciter.
then the FADEC controls the fuel according to the start fuel schedule

NOTE: for airstart, when alternative start is selected, the FADEC always commands a starter assisted airstart
in alternate mode the FADEC performs the same monitoring than in automatic start, and provides the same warning indications but the starting interruption is under manual control.

(b) Start interruption
Interruption of alternative start is possible by :

releasing the ENG/MAN START pushbutton switch if the ENG MASTER switch is OFF
selection of the ENG MASTER switch back to OFF if it is ON.

(4) Engine shut-off
If the ENG MASTER switch is set to the OFF position, an engine off signal is sent to the FADEC. The HP fuel shut-off valve is directly closed.
The FADEC does not have the capability to turn fuel off except during automatic ground start.
The direct signal from cockpit has always the priority over the FADEC for shutting the engine down even if the FADEC commands a HP fuel shut-off valve open.

F. Thrust reverser control

(1) ECU control logic
The ECU thrust reverser logic has four basic functions.
These functions are invoked in response to the flight/ground status, the engine status, the calculated Mach number, the throttle control lever angle value and the thrust reverser doors position.
These functions are:

the position hold function assures that the thrust reverser does not move when the aircraft is on the ground with the engine not running (when not in menu mode T/R test)
the reverse inhibit function ensures that in flight with the engine not running, the TRPV is commanded closed and idle automatically commanded if TLA is set in reverse area.
the forward thrust function commands the thrust reverser doors to restow if at least one door is detected to be unstowed and the aircraft is on ground. This function ensures also that engine power will be limited to idle, overriding the throttle control lever position when at least one door is unstowed (or in determined door position) and the thrust reverser system is pressurized or if 4 doors are detected unstowed
the reverse thrust function will deploy the thrust reverser doors if the aircraft is validated on ground with the engine running and has been commanded through the thrust reverser control lever

(2) EIU directional control valve supply
The EIU switches aircraft 28VDC to the directional control valve solenoid when thrust reverser control lever is in reverse area. This information is independent of the one provided to the ECU. The ECU has its own resolver for the thrust reverser control lever position acquisition.

(3) Design precaution
To deploy the thrust reverser doors, three commands are necessary:

control of isolation control valve (TRPV) from ECU, Directional Control Valve (TRDV) from ECU
control of TRDV supply from EIU.

Thrust reverser command is provided through thrust reverser control lever and is given from separate sources to EIU and to ECU.
The ECU monitors the reversing system and is able to reduce the engine thrust to idle in case of reversing system malfunction. Furthermore an additional shut-off Valve (SOV) upstream of the HCU isolates the thrust reverser system from the hydraulic power supply. This SOV is commanded by the Spoiler Elevator Computer (SEC) based on the throttle lever and radioaltimeters information.

G. 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).

H. Engine Condition Parameters Transmission
Engine condition monitoring is possible, by the ability of the FADEC to broadcoast 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, FRV, HPTCC, WF, RACSB, and LPTACC valve or actuator position
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 P13, P25 and T5.

I. FADEC System Fault Diagnostics

(1) Fault Detection
The FADEC maintenance is eased by internal extensive Built-In Test Equipment allowing an efficient fault detection.
The efficiency of this fault detection is at least 95 percent of probable failures of INPUT/OUTPUT and ECU. Failure isolation of no more than 3 specific electrical LRU's accomplished with a 85 percent efficiency.
The result of this fault detection is contained in status and maintenance words according to ARINC 429 specification and is 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 are data stored into 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 provides engine control system self-testing to detect problem at LRU level.
The FADEC is such that no engine ground run for trim purposes is necessary after component replacement.

J. Engine Sensors

(1) T12 Sensor

(a) General
The T12 sensor is made to measure the engine intake air temperature. It is installed on the engine fan inlet case 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 4:30 o'clock upstream of variable bleed (VBV) in fan frame. The sensor measures the air temperature downstream of the booster (or HP compressor inlet). 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) T495 Thermocouple Harness
The T495 thermocouple harness (Ref. AMM D/O 77-20-00-00).

(4) N1 Speed Sensor
The N1 sensor (Ref. AMM D/O 77-10-00-00).

(5) N2 Speed Sensor
The N2 sensor (Ref. AMM D/O 77-10-00-00).

(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 9 o'clock ahead of fan frame, in front of the engine mount
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 attachment 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 electrical harness.

K. Permanent Magnetic Alternator (control 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 ECU needs above 12 percent 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.

L. 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 busses. 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 an On/Off control of the Ignition Relays, Starter Air Valve Solenoid, the Aircraft Thrust Reverser Directional Valve and the Thrust Reverser Pressurizing Valve.
The ECU provides digital data output in ARINC 429 format to the aircraft for 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 percent 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 and is cooled through passive air ventilation.

M. Hydromechanical Unit

(1) General
The hydromechanical unit (HMU) is attached to the aft section of the fuel pump unit housing. The HMU/fuel pump package is installed on the aft side of the AGB, left-hand side of the horizontal drive shaft housing. The HMU 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 media.

Hydromechanical Unit ** ON A/C NOT FOR ALL

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

HMU Block Diagram for SAC engine ** ON A/C NOT FOR ALL

HMU Block Diagram for DAC engine ** 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 Start Bleed 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 shut-off valve shuts off fuel flow to the engine in response to an electrical signal commanded by the ENG MASTER SWITCH 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 and 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 electrical signal commanded by the ENG MASTER SWITCH.

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

The fuel shut-off solenoid is energized by aircraft 28VDC. 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 (ENG MASTER SWITCH ON position) (solenoid de-energized)
engine rotation speed above 15 percent N2
fuel flow requested by the ECU.

(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 in excess of 105.8 percent N2.

N. Electrical Harnesses.

(1) General.
The electrical connections between the various electrical, electronic and electromechanical engine-mounted components or accessories are provided by 2 types of harnesses, as follows:

(a) The harnesses which run on the core engine and on the low pressure turbine assembly. These harnesses have a special design to withstand the high temperature environment of the engine hot section.

(b) The harnesses which run on the fan inlet case and on the fan frame (engine cold section). Such harnesses have a more conventional design.

NOTE: All the harnesses running on the core engine and on the low pressure turbine and turbine frame assembly converge toward the 6 o'clock tube bundle and harness junction box (6 o'clock box). This box provides an interface between the 2 designs of harness, depending on whether the signals to be conveyed initiate from the core engine or from the low pressure turbine and turbine frame assembly.

(2) Description.

(a) Harnesses which have their routing on the Core Engine (HPC, Combustor Case and HPT) and on the Low Pressure Turbine. These harnesses are designated: CJ11L, CJ11R, CJ12L, CJ12R and CJ13.

1 Harness CJ11L consists of:

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

a One bulkhead connector (CL111) for passage through, and attachment to the L-H inner wall of the 6 o'clock tube bundle junction box (ALF) with a nut.

b One stainless steel connection box, integral with connector CL111.

c Two branches identified RACSB-A and VBV-A.

d Two mobile connectors: CL112 and CL113.

CL112 connects to connector A of VBV position sensor.
CL113 connects to the connector A of the RACSB valve position sensor.

2 Harness CJ11R consists of:

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

a One bulkhead connector (CR111) for passage through the RH wall of the 6 o'clock tube bundle junction box (ALF).

b One round-shaped connection box with a flange for attachment to the R-H outer wall of tube bundle junction box. Internally, this connection box provides for attachment of bulkhead connector (CR111).

c Five branches identified BSV-A, T25-A, LPTCC-A, HPTCC-A and VSV-A. The LPTCC-A and HPTCC-A branches have each a T-shaped metal fitting with one mounting lug for attachment to the engine. The T25-A branch has an angled metal fitting with one mounting lug for attachment to the engine.

d Five mobile connectors: CR112, CR113, CR114, CR116 and CR115.

CR112 connects to connector A of T25 temperature sensor.
CR113 connects to connector A of VSV position sensor.
CR114 connects to connector A of LPTACC valve position sensor.
CR115 connects to connector A of HPTACC valve position sensor.
CR116 connects to connector A of BSV switch.

3 Harness CJ12L consists of:

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

a One bulkhead connector (CL121) for passage through and attachment to the L-H inner wall of the tube bundle junction box with a nut.

b One stainless steel, V-shaped connection box.

c Three branches identified VBV-B, VSV-B, and RACSB-B.

d Three mobile connectors: CL122, CL123, and CL124:

CL122 connects to connector B of VBV position sensor.
CL123 connects to connector B of VSV position sensor.
CL124 connects to connector B of RACSB valve position sensor.

e One rigid fitting for attachment to the engine.

4 Harness CJ12R consists of:

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

a One bulkhead connector (CR121) for passage through the RH wall of the 6 o'clock tube bundle junction box (ALF).

c Four branches identified T25-B, LPTACC-B, BSV-B and HPTACC-B. The LPTACC and HPTACC branches share a T-shaped metal fitting with one mounting lug for attachment to the engine. The T25-B branch has a metal fitting with a lug for attachment to the engine.

d Four mobile connectors: CR122, CR123, CR124 and CR125:

CR122 connects to connector B of T25 temperature sensor.
CR123 connects to connector B of LPTACC valve position sensor.
CR124 connects to connector B of HPTACC valve position sensor.
CR125 connects to connector B of BSV switch.

5 Harness CJ13 consists of:

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

NOTE: All the lines which make the CJ13 harness are Chromel and Alumel wires.

a One bulkhead connector (C135) for passage through the LH wall of the 6 o'clock tube bundle junction box (ALF).

b One square-shaped junction box with two through holes for hard point attachment to the engine.

c One rectangular-shaped junction box with two lugs for hard point attachment to the engine.

PRE SB CFM 73-046

d Six branches identified TCC-A, TCC-B, T49.5, T5, T3-B and T3-A.

POST SB CFM 73-046

e Five branches identified TCC, T49.5, T5, T3-B and T3-A.

END OF SB CFM 73-046

PRE SB CFM 73-046

f Six mobile connectors: C136, C137, C138, C139, C140 and C141:

C136 connects to connector of HPT Case temperature sensor, Channel A.
C137 connects to connector of HPT Case temperature sensor, Channel B.
C138 connects to connector of T49.5 temperature sensor.
C139 connects to connector of T5 temperature sensor.
C140 connects to connector of T3 temperature sensor, Channel B.
C141 connects to connector of T3 temperature sensor, Channel A.

POST SB CFM 73-046

g Five mobile connectors: C137, C138, C139, C140 and C141:

C137 connects to connector of HPT Case temperature sensor, Channel A and Channel B.
C138 connects to connector of T49.5 temperature sensor.
C139 connects to connector of T5 temperature sensor.
C140 connects to connector of T3 temperature sensor, Channel B.
C141 connects to connector of T3 temperature sensor, Channel A.

END OF SB CFM 73-046

(b) Harnesses which have their routing on the Fan Inlet Case and Fan Frame. These harnesses are designated: HJ7, HJ8, HJ9, HJ10, HJ11, HJ12, HJ13 and DPM.

1 Harness HJ7 consists of:

Electrical Wiring Harness HJ7 ** ON A/C NOT FOR ALL

a One primary branch, identified J7, with a mobile connector (C71) for connection with ECU receptacle J7.

b Three secondary branches identified HMU-A, FRV-A and N2-A.

c Three mobile connectors: C72, C73 and C74:

C72 connects to connector A of HMU
C73 connects to connector A of FRV
C74 connects to connector A of N2 speed sensor.

d Two T-shaped derivations.

2 Harness HJ8 consists of:

Electrical Wiring Harness HJ8 ** ON A/C NOT FOR ALL

a One primary branch, identified J8, with a mobile connector (C81) for connection with ECU receptacle J8.

b Three secondary branches identified HMU-B, FRV-B and N2-B.

c Three mobile connectors: C82, C83 and C84:

C82 connects to connector B of HMU
C83 connects to connector B of FRV
C84 connects to connector B of N2 speed sensor.

3 Harness HJ9 consists of:

Electrical Wiring Harness HJ9 ** ON A/C NOT FOR ALL

a One primary branch, identified J9, with a mobile connector (C91) for connection with ECU receptacle J9.

b Four secondary branches identified N1-A, ALT-A and SAV START-A and T12-A.

c Four mobile connectors: C92, C93 and C94 and C95:

C92 connects to connector A of T12 temperature sensor.
C93 connects to connector A of control alternator.
C94 connects to connector A of starter air valve position switch.
C95 connects to connector A of N1 speed sensor.

d Three T-shaped derivations.

4 Harness HJ10 consists of:

Electrical Wiring Harness HJ10 ** ON A/C NOT FOR ALL

a One primary branch, identified J10, with a mobile connector (C101) for connection with ECU receptacle J10.

b Four secondary branches identified N1-B, ALT-B and SAV START-B and T12-B.

c Four mobile connectors: C102, C103 and C104 and C105:

C102 connects to connector B of T12 temperature sensor.
C103 connects to connector B of control alternator.
C104 connects to connector B of starter air valve position switch.
C105 connects to connector B of N1 speed sensor.

d Three T-shaped derivations.

5 Harness HJ11 consists of:

Electrical Wiring Harness HJ11 ** ON A/C NOT FOR ALL

a One primary branch, identified J11, with a mobile connector (C111) for connection with ECU receptacle J11.

b Two secondary branches, each identified 6H BOX.

c Two mobile connectors: C112, and C113:

C112 (straight connector) connects to the CR111 bulkhead connector (inside the 6 o'clock tube bundle junction box).
C113 (135 degrees-angled connector) connects to the CL111 bulkhead connector (inside the 6 o'clock tube bundle junction box).

d One Y-shaped derivation.

6 Harness HJ12 consists of:

Electrical Wiring Harness HJ12 ** ON A/C NOT FOR ALL

a One primary branch, identified J12, with a mobile connector (C121) for connection with HCU receptacle J12.

b Two secondary branches each identified 6H BOX.

c Two mobile connectors: C122, and C123:

C122 (straight connector) connects to the CL121 bulkhead connector (inside the 6 o'clock tube bundle junction box).
C123 (135 degrees-angled connector) connects to the CR121 bulkhead connector (inside the 6 o'clock tube bundle junction box).

d One Y-shaped derivation.

7 Harness HJ13 consists of:

Electrical Wiring Harness HJ13 ** ON A/C NOT FOR ALL

a One primary branch, identified J13, with a mobile connector (C131) for connection with HCU receptacle J13.

b Three secondary branches identified OIL TEMP., FUEL FLOWMETER, and 6H BOX.

c Three mobile connectors: C132, and C133 and C134.

C132 connects to the engine oil temperature sensor receptacle connector (channel A and channel B).
C133 connects to the fuel flowmeter receptacle connector.
C134 connects to the C135 bulkhead connector (inside the 6 o'clock tube bundle junction box).

d One Y-shaped derivation.

8 The Harness DPM consists of:

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

a One two-wire cable identified DPM at one end, and INDICT. VISUAL at the other end.

b Two mobile connectors C01 and C02:

C01 connects to the pop-out-type visual indicator.
C02 connects to the (electrical) master magnetic chip detector.

(3) Operation

(a) Harnesses with their Routing on the Core Engine (HPC, Combustor Case and HPT) and on the Low Pressure Turbine

1 Harness CJ11L

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

Provides the electrical interface (Channels A) between the 6 o'clock tube bundle junction box (where it connects to mobile connector C113 from harness HJ11) and:

receptacle connector A of VBV position sensor
receptacle connector A of RACSB valve position sensor.

2 Harness CJ11R

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

Provides the electrical interface (Channels A) between the 6 o'clock tube bundle junction box (where it connects to mobile connector C112 from harness HJ11) and:

receptacle connector A of T25 temperature sensor
receptacle connector A of VSV position sensor
receptacle connector A of LPTACC valve position sensor
receptacle connector A of HPTACC valve position sensor
receptacle connector A of BSV switch.

3 Harness CJ12L

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

Provides the electrical interface (Channels B) between the 6 o'clock tube bundle junction box (where it connects to mobile connector C122 from harness HJ12) and:

receptacle connector B of VBV position sensor
receptacle connector B of VSV position sensor
receptacle connector B of RACSB valve position sensor.

4 Harness CJ12R

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

Provides the electrical interface (Channels B) between the 6 o'clock tube bundle junction box (where it connects to mobile connector C123 from harness HJ12) and:

receptacle connector B of T25 temperature sensor
receptacle connector B of LPTACC valve position sensor
receptacle connector B of HPTAC valve position sensor
receptacle connector B of BSV switch.

5 Harness CJ13

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

Provides the Cr and Al thermocouple junctions interface between the 6 o'clock tube bundle junction box (where it connects to mobile connector C134 from harness HJ13) and the following thermocouple sensors:

the two HPT case temperature sensors, Channels A and B
the nine T495 (EGT) temperature probes (averaged in the T495 thermocouple harness)
the two T3 temperature sensors (Channels A and B)
the T5 temperature sensor.

(b) Harnesses with their Routing on the Fan Inlet Case and the Fan Frame

1 Harness HJ7

Electrical Wiring Harness HJ7 ** ON A/C NOT FOR ALL

Provides the electrical interface (Channels A) between the ECU (receptacle J7) and:

receptacle connector A of HMU
receptacle connector A of Fuel Return Valve (FRV)
receptacle connector A of N2 speed sensor.

2 Harness HJ8

Electrical Wiring Harness HJ8 ** ON A/C NOT FOR ALL

Provides the electrical interface (Channels B) between the ECU (receptacle J8) and:

receptacle connector B of HMU
receptacle connector B of Fuel Return Valve (FRV)
receptacle connector B of N2 Speed sensor.

3 Harness HJ9

Electrical Wiring Harness HJ9 ** ON A/C NOT FOR ALL

Provides the electrical interface (Channels A) between the ECU (receptacle J9) and:

receptacle connector A of T12 temperature sensor
receptacle connector A of control alternator
receptacle connector A of starter air valve solenoid position sensor (switch A)
receptacle connector A of N1 speed sensor.

4 Harness HJ10

Electrical Wiring Harness HJ10 ** ON A/C NOT FOR ALL

Provides the electrical interface (Channels B) between the ECU (receptacle J10) and:

receptacle connector B of T12 temperature sensor
receptacle connector B of control alternator
receptacle connector B of Starter air valve solenoid position sensor (switch B).

5 Harness HJ11

Electrical Wiring Harness HJ11 ** ON A/C NOT FOR ALL

Provides the electrical interface (Channels A) between the ECU (receptacle J1) and:

the 6 o'clock tube bundle junction box where it connects to the bulkhead connector CL111 from harness CJ11L (Channels A)
the 6 o'clock tube bundle junction box where it connects to the bulkhead connector CR111 from harness CJ11R (Channels A).

6 Harness HJ12

Electrical Wiring Harness HJ12 ** ON A/C NOT FOR ALL

Provides the electrical interface (Channels B) between the ECU (receptacle J12) and:

the 6 o'clock tube bundle junction box where it connects to the bulkhead connector CL121 from harness CJ12L (Channels B)
the 6 o'clock tube bundle junction box where it connects to the bulkhead connector CR121 from harness CJ12R (Channels B).

7 Harness HJ13

Electrical Wiring Harness HJ13 ** ON A/C NOT FOR ALL

Provides the Cr and Al thermocouple junctions interface, (Channels A and B) between the ECU (receptacle J13) and:

receptacle connector (Channels A and B) of engine oil temperature sensor
receptacle connector of fuel flowmeter
the 6 o'clock tube bundle junction box where (one of its branches) connects to the bulkhead connector C135 from harness CJ13 (Channels A and B).

8 Harness DPM

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

Provides a discrete electrical interface between the master magnetic chip detector and the pop-out visual indicator.

NOTE: This harness connects in series in the electrical loop which detects the magnetic particles in the oil system. The detection loop is supplied with a dedicated 28VDC line from the aircraft network.

O. Identification Connector

(1) General
The hybrid identification connector provides the Electronic Control unit (ECU) with the engine configuration for proper engine operation through the following electric coded signals:

(a) using electrical fuse technology which provides irreversible coding:

thrust rating/bump
connector type (5A or 5B)

(b) using push-pull connections which provides reversible coding:

engine configuration (5B or 5B/P)
system configuration (engine combustor type): SAC, DAC 1, DAC 2 FN, DAC 2 COMB (DAC 2 PIP)
N1 trim level: trim from 0 to 7
overthrust protection: Thrust Control Malfunction Accommodation shutdown function enable/disable
Core Chevron Nozzle installed / not installed status (N1K adjuster for acoustic Core Chevron Nozzle / no adjustment for basic nozzle exhaust)
monitoring parameters: with or without PMUX status
Nacelle Active Cooling (NACTB) installed/ not installed status for CFM56-5Bx/2P.
It is connected to the J14 ECU fixed connector. It is attached to the fan case by a metal strap and remains with the engine after any ECU replacement.
The data coded using electrical fuse technology (irreversible coding) is programmed by the engine manufacturer.
The reversible process can be performed by the customer.

(2) Description

Identification Connector ** ON A/C NOT FOR ALL

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

A mobile connector incorporating the following items:
31 sockets
a black shell bolted onto the plug to protect the back (where the push-pull contacts are located) and to link the identification plug with the engine by means of a cable
a safety wire holding the cover/plug assembly in case of loosening
a metallic braid connected as follows:
- riveted on the rear end of the connector.
- screwed 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 and translated into precise engine characteristics in order to:

pilot the engine control system
document the aircraft Multi purpose Control and Display Unit (MCDU) for all the engine information coded in the identification connector.

P. Ignition Boxes
They are powered with 115VAC through the EIU and FADEC. One of the ignition boxes is powered from a normal busbar, 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.

Q. Starter Shut-off Valve
The FADEC controls the opening and closing of the starter valve and receives the open/not open signal of the valve.

R. VSV Feedback Signal
The FADEC receives a VSV position signal feedback from the VSV actuator (Ref. 75-30-00)

S. VBV Feedback Signal
Same as VSV feedback signal.

T. HPTACC Feedback Signal
Same as VSV feedback signal.

U. LPTACC Feedback Signal
Same as VSV feedback signal.

V. RACSB Feedback Signal
Same as VSV feedback signal.

[Rev.10 from 2021] 2026.04.01 02:58:19 UTC