DOC AIRBUS | AMM A320FCONTROLLING - DESCRIPTION AND OPERATION
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
1. General
The Full Authority Digital Electronic Control (FADEC) system provides full range control of the engine to achieve steady state and transient performance when operated in combination with aircraft subsystems.
The FADEC system consists of: a dual-channel FADEC unit; Fuel Metering Unit (FMU); dedicated Permanent Magnetic Alternator (PMA); actuation systems for stator vanes, engine bleeds, active clearance control, 10th stage cooling air, engine and Integrated Drive Generator (IDG) heat management control; sensors; electrical harness; and start system components.
The FADEC Electronic Engine Control (EEC) is a vibration-isolated, air-cooled unit mounted on the engine fan case. Its vibration isolation and cooling systems are specifically designed to provide a protected and controlled internal environment that is completely compatible with the electronic components.
** ON A/C NOT FOR ALL The Full Authority Digital Electronic Control (FADEC) system provides full range control of the engine to achieve steady state and transient performance when operated in combination with aircraft subsystems.
The FADEC system consists of: a dual-channel FADEC unit; Fuel Metering Unit (FMU); dedicated Permanent Magnetic Alternator (PMA); actuation systems for stator vanes, engine bleeds, active clearance control, 10th stage cooling air, engine and Integrated Drive Generator (IDG) heat management control; sensors; electrical harness; and start system components.
The FADEC Electronic Engine Control (EEC) is a vibration-isolated, air-cooled unit mounted on the engine fan case. Its vibration isolation and cooling systems are specifically designed to provide a protected and controlled internal environment that is completely compatible with the electronic components.
2. System Description
A. FADEC
(1) FADEC Functions
The FADEC system operates compatibly with applicable aircraft systems to perform the following functions
The FADEC system operates compatibly with applicable aircraft systems to perform the following functions
Full Authority Digital Electronic Control - Schematic(a) GAS generator control for steady state and transient engine operation within safe limits.
- Fuel flow control
- Acceleration and deceleration schedules
- Variable Stator Vane (VSV) and Booster Stage Bleed Valve (BSBV) schedules
- Turbine clearance control (High Pressure/Low Pressure) (HP/LP)
- 10th stage cooling air control
- Idle setting.
(b) Engine limits protection
- Fan and core overspeed protection to prevent engine running over certified red lines
- Engine turbine outlet gas temperature monitoring.
(c) Power management
- 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 control lever position
. flex take-off at constant intermediate position whatever the derating is
. other ratings (max continuous, max climb, idle, max reverse) at associated throttle lever detent points. - Automatic power management through direct engine power adjustment to the autothrust system demand.
(d) Automatic engine start sequencing
- Control of the starter valve ON/OFF
- Control of HP fuel shutoff valve (ON/OFF on ground, ON in flight)
- Control of the fuel schedule
- Control of the ignition (ON/OFF)
- Engine Pressure Ratio (EPR), N1, N2, WF, Exhaust Gas Temperature (EGT) monitoring
- Abort/Recycle capability on ground.
(e) Thrust reverser control
- Control of thrust reverser actuation (deployment and stowage)
- Control of engine power during reverser operation.
. engine idle setting during reverser transient - Control of maximum reverser power at full rearward throttle control lever position.
- Restow command in case of non commanded deployment.
- Redeploy command in case of non commanded stowage.
(f) Engine parameters transmission for cockpit indication
- Engine primary 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
The FADEC controls the ON/OFF return to the aircraft tank in relationship with:
The FADEC controls the ON/OFF return to the aircraft tank in relationship with:
- Engine oil, IDG oil and fuel temperatures
- Aircraft fuel system configuration
- Flight phases.
(2) Fuel Metering Unit
The FMU provides fuel flow control for all operating conditions.
Variable fuel metering is provided by the FMU through EEC commands by a torque motor controlled servo drive. Position resolvers provide feedback to the EEC. The FMU has provision to route excess fuel (above engine requirements) to the fuel diverter valve through the bypass loop.
The FMU provides fuel flow control for all operating conditions.
Variable fuel metering is provided by the FMU through EEC commands by a torque motor controlled servo drive. Position resolvers provide feedback to the EEC. The FMU has provision to route excess fuel (above engine requirements) to the fuel diverter valve through the bypass loop.
(4) Additional Engine Sensing (AES)
B. Gas Generator Control
(1) Fuel Control
(a) General
The EEC produces a fuel flow request using the control laws relevant to engine operation. The request is transmitted through the torque motor in the fuel metering unit. Setting steady state power, idle speed and accel/decel transients requires different control laws.
The primary mode of setting steady state power is provided by controlling fuel flow to set EPR as illustrated in
An EPR Reference (EPR REF) is calculated as a function of the Throttle Resolver Angle (TRA), ambient temperature (T2), Mach number and altitude. The EPR reference is compared to sensed EPR and dynamic compensation is then applied to this EPR error. The result is that fuel flow is modulated until the EPR error is eliminated.
If the control is unable to sense EPR or calculate EPR REF, a transition to an N1 reversionary control mode will take place.
In the event of this transition, EEC logic is incorporated to prevent thrust perturbation when control is transferred from EPR to the reversionary control mode. The rotor speed reference (N1 REF) will be scheduled as a function of TRA and T2.
The EEC produces a fuel flow request using the control laws relevant to engine operation. The request is transmitted through the torque motor in the fuel metering unit. Setting steady state power, idle speed and accel/decel transients requires different control laws.
The primary mode of setting steady state power is provided by controlling fuel flow to set EPR as illustrated in
An EPR Reference (EPR REF) is calculated as a function of the Throttle Resolver Angle (TRA), ambient temperature (T2), Mach number and altitude. The EPR reference is compared to sensed EPR and dynamic compensation is then applied to this EPR error. The result is that fuel flow is modulated until the EPR error is eliminated.
If the control is unable to sense EPR or calculate EPR REF, a transition to an N1 reversionary control mode will take place.
In the event of this transition, EEC logic is incorporated to prevent thrust perturbation when control is transferred from EPR to the reversionary control mode. The rotor speed reference (N1 REF) will be scheduled as a function of TRA and T2.
(b) Idle power level
Engine power level at idle is determined by selecting the highest of three possible controlling loops as shown in
Then it is compared to the fuel flow derivative based on minimum burner pressure and the highest one is selected.
Engine power level at idle is determined by selecting the highest of three possible controlling loops as shown in
- The first N2 is a constant corrected N2 (N2/square of theta T2) which provides constant thrust under various ambient conditions and varying customer bleed and horse power extraction.
- Approach idle is the second constant N2 speed which varies as a function of total air temperature and altitude. This idle speed is selected to ensure sufficiently short acceleration time to go around thrust and is used when the aircraft is in an approach configuration.
- The third requirement is for a minimum mechanical N2 speed to avoid cut out of the electrical generator.
Then it is compared to the fuel flow derivative based on minimum burner pressure and the highest one is selected.
NOTE: The minimum requirement for burner pressure is determined as a function of altitude. It is compared to actual burner pressure and the error term is used to determine the fuel flow derivative request.
Finally, the selected fuel flow derivative is integrated and compared to the minimum fuel flow required to prevent burner blow out. The highest fuel flow requested is used as the command.
Finally, the selected fuel flow derivative is integrated and compared to the minimum fuel flow required to prevent burner blow out. The highest fuel flow requested is used as the command.
(c) Engine acceleration/deceleration
Engine acceleration/deceleration is accomplished as a function of N2Dot (N2 speed derivative) to provide consistent power response with and without bleed load throughout the engine life. A ratio unit topper (Wf/Pb) is also provided to protect engine integrity under abnormal engine conditions such as surge. Fuel flow for engine starting is scheduled as a function of ratio units (Wf/Pb).
The N2Dot acceleration schedule is a function of N2/square root of theta T2 (N2 to conditions at the high compressor inlet) with an altitude bias.
In the event of a fast decel, the accel schedule is transiently reduced in anticipation of a throttle movement. This reset is removed when the deceleration transient detection clears and a follow-on variable timer elapses. The scheduled N2 derivative is compared to the actual N2 derivative to form an error term, and dynamically compensated. The output is limited by an acceleration WfDot/Wf rate limit.
The N2Dot deceleration schedule is a function of N1/square root of theta T2 and altitude.
The decel N2Dot schedule is compared to the actual N2 derivative to form an error term, and dynamically compensated. The output is limited by a deceleration WfDot/Wf rate limit.
In the event of an engine surge, a ratio unit accel schedule (Wf/Pb) will be in control to reduce fuel flow. Scheduled ratios are a function of N2/square root of theta T2.6. If a surge is detected, the requested ratio units are reduced to aid in recovery.
Fuel for engine starting and acceleration to idle is computed from a Wf/Pb start schedule and Pb. The schedule is a function of N2/square root of theta T2 and P2.
Engine acceleration/deceleration is accomplished as a function of N2Dot (N2 speed derivative) to provide consistent power response with and without bleed load throughout the engine life. A ratio unit topper (Wf/Pb) is also provided to protect engine integrity under abnormal engine conditions such as surge. Fuel flow for engine starting is scheduled as a function of ratio units (Wf/Pb).
The N2Dot acceleration schedule is a function of N2/square root of theta T2 (N2 to conditions at the high compressor inlet) with an altitude bias.
In the event of a fast decel, the accel schedule is transiently reduced in anticipation of a throttle movement. This reset is removed when the deceleration transient detection clears and a follow-on variable timer elapses. The scheduled N2 derivative is compared to the actual N2 derivative to form an error term, and dynamically compensated. The output is limited by an acceleration WfDot/Wf rate limit.
The N2Dot deceleration schedule is a function of N1/square root of theta T2 and altitude.
The decel N2Dot schedule is compared to the actual N2 derivative to form an error term, and dynamically compensated. The output is limited by a deceleration WfDot/Wf rate limit.
In the event of an engine surge, a ratio unit accel schedule (Wf/Pb) will be in control to reduce fuel flow. Scheduled ratios are a function of N2/square root of theta T2.6. If a surge is detected, the requested ratio units are reduced to aid in recovery.
Fuel for engine starting and acceleration to idle is computed from a Wf/Pb start schedule and Pb. The schedule is a function of N2/square root of theta T2 and P2.
(2) Variable Stator Vane (VSV) Control
The VSV position is controlled by the EEC as a function of N2/square root of theta T2.6.
The EEC uses the VSV feedback signal from the Linear Variable Differential Transducer (LVDT) to adjust the actual VSV position. The VSV control schematic is given on
The VSV position is controlled by the EEC as a function of N2/square root of theta T2.6.
The EEC uses the VSV feedback signal from the Linear Variable Differential Transducer (LVDT) to adjust the actual VSV position. The VSV control schematic is given on
(3) Booster Stage Bleed Valve (BSBV) Control
The BSBV position is controlled by the EEC. The EEC uses the BSBV feedback signal from the LVDT to adjust the actual BSBV position.
The BSBV control schematic is given on
The BSBV position is controlled by the EEC. The EEC uses the BSBV feedback signal from the LVDT to adjust the actual BSBV position.
The BSBV control schematic is given on
(4) HPT/LPT Active Clearance Control (HPT/LPT ACC)
The HPT/LPT ACC valve modulates fan air flow to the HP and LP turbine cases.
The EEC controls the valve position as a function of the thrust level.
The LVDTs transmit the valve position to the EEC.
The HPT/LPT ACC schematic is given on
The HPT/LPT ACC valve modulates fan air flow to the HP and LP turbine cases.
The EEC controls the valve position as a function of the thrust level.
The LVDTs transmit the valve position to the EEC.
The HPT/LPT ACC schematic is given on
(5) HP Turbine (10th Stage) Cooling Air Control
The HP turbine cooling air valve supplies supplemental air (from HP compressor 10th stage) to cool various parts of the HP and LP turbines.
The valve operates as a function of high rotor speed and altitude and incorporates a 2-position switch to provide a feedback signal to the EEC (channels A and B)
The HP turbine cooling air valve supplies supplemental air (from HP compressor 10th stage) to cool various parts of the HP and LP turbines.
The valve operates as a function of high rotor speed and altitude and incorporates a 2-position switch to provide a feedback signal to the EEC (channels A and B)
(6) Oil/Fuel Temperature Control
(a) General
Heating and cooling of fuel, engine oil and IDG oil is accomplished by the Fuel Cooled Oil Cooler (FCOC), the Air Cooled Oil Cooler (ACOC) and the IDG cooler under the management of the EEC. Devices used by the EEC include the fuel diverter valve, the ACOC modulating air valve and the return to tank valve. Fuel, engine oil and IDG oil temperatures are transmitted to the EEC by thermocouples.
The fuel temperature is measured at the exit of the filter. The engine oil temperature is measured upstream of the ACOC. The IDG oil temperature is measured at IDG oil cooler exit.
Heating and cooling of fuel, engine oil and IDG oil is accomplished by the Fuel Cooled Oil Cooler (FCOC), the Air Cooled Oil Cooler (ACOC) and the IDG cooler under the management of the EEC. Devices used by the EEC include the fuel diverter valve, the ACOC modulating air valve and the return to tank valve. Fuel, engine oil and IDG oil temperatures are transmitted to the EEC by thermocouples.
The fuel temperature is measured at the exit of the filter. The engine oil temperature is measured upstream of the ACOC. The IDG oil temperature is measured at IDG oil cooler exit.
(b) ACOC modulating air valve
The modulating air valve regulates air flow to the ACOC. Oil heated by the engine passes through the ACOC and then to the FCOC. The air valve is modulated by the EEC to maintain both oil and fuel temperatures within acceptable minimum and maximum limits. Minimum oil temperature limits are used such that the oil may be used to prevent fuel icing with the use of FCOC. Maximum limits have been established to avoid breakdown of engine oil and to avoid excessively high fuel temperatures.
The modulating air valve regulates air flow to the ACOC. Oil heated by the engine passes through the ACOC and then to the FCOC. The air valve is modulated by the EEC to maintain both oil and fuel temperatures within acceptable minimum and maximum limits. Minimum oil temperature limits are used such that the oil may be used to prevent fuel icing with the use of FCOC. Maximum limits have been established to avoid breakdown of engine oil and to avoid excessively high fuel temperatures.
(c) Fuel diverter and return to tank valve
The fuel diverter valve and the return to tank valve are controlled by the EEC to provide the selection of four modes of operation shown schematically in figures
The two-position fuel diverter valve, controlled by a single EEC signal, and the return to tank valve, which varies flow from a maximum to zero flow in response to a modulated EEC command, are both contained in the same housing.
The four modes of operation, described below, are intended to maintain fuel, engine oil and IDG oil temperatures in limits while minimizing AOC cooling air usage. Return to tank is inhibited under certain power conditions as well as other aircraft fuel system conditions determined by aircraft logic.
The fuel diverter valve and the return to tank valve are controlled by the EEC to provide the selection of four modes of operation shown schematically in figures
The two-position fuel diverter valve, controlled by a single EEC signal, and the return to tank valve, which varies flow from a maximum to zero flow in response to a modulated EEC command, are both contained in the same housing.
The four modes of operation, described below, are intended to maintain fuel, engine oil and IDG oil temperatures in limits while minimizing AOC cooling air usage. Return to tank is inhibited under certain power conditions as well as other aircraft fuel system conditions determined by aircraft logic.
1 Mode 1
Fuel through the IDG FCOC or combined with a quantity of fuel downstream of the FCOC is modulated for return to tank. FMU bypass flow is returned upstream of fuel filter. This is the normal mode of operation.
This mode is maintained if the following conditions are satisfied:
Fuel through the IDG FCOC or combined with a quantity of fuel downstream of the FCOC is modulated for return to tank. FMU bypass flow is returned upstream of fuel filter. This is the normal mode of operation.
This mode is maintained if the following conditions are satisfied:
- engine at low power setting,
- return to tank valve not fully open to maintain IDG oil temperature to 85 deg.C (180 deg.F).
2 Mode 4
Fuel through IDG FCOC modulated for fuel return to tank. FMU bypass flow returned upstream of FCOC. Supplemental cooling of fuel is provided by this mode.
This mode is adopted at low engine speeds with a high IDG oil inlet temperature.
Fuel through IDG FCOC modulated for fuel return to tank. FMU bypass flow returned upstream of FCOC. Supplemental cooling of fuel is provided by this mode.
This mode is adopted at low engine speeds with a high IDG oil inlet temperature.
3 Mode 3
Fuel through IDG FCOC returned downstream of FCOC. FMU bypass flow returned upstream of fuel filter. Return to tank inhibited. This is the preferred mode of operation when return to tank is not allowed.
This mode is maintained if the following conditions are satisfied:
Fuel through IDG FCOC returned downstream of FCOC. FMU bypass flow returned upstream of fuel filter. Return to tank inhibited. This is the preferred mode of operation when return to tank is not allowed.
This mode is maintained if the following conditions are satisfied:
- engine at high power setting,
- ACOC not fully open,
- IDG oil temperature not greater than 110 deg.C (230 deg.F) or 100 deg.C ( 212 deg.F) on ground.
4 Mode 5
FMU bypass flow returned upstream of FCOC via the IDG cooler in the reverse direction. Return to tank inhibited. This mode is adopted if the conditions exist:
FMU bypass flow returned upstream of FCOC via the IDG cooler in the reverse direction. Return to tank inhibited. This mode is adopted if the conditions exist:
- fuel temperature less than 5 deg.C (41 deg.F),
- oil temperature less than 30 deg.C (86 deg.F),
- ACOC fully open in mode 3,
- IDG OIL temperature greater than 100 deg.C (212 deg.F) in mode 4,
- IDG OIL temperature greater than 110 deg.C (230 deg.F) in mode 3.
C. Engine Limits Protection
(1) General
The FADEC prevents inadvertent overboosting of the expected rating (EPR limit and EPR target) during power setting.
It also prevents exceedance of rotor speeds (N1 and N2) and burner pressure limits. In addition, the FADEC unit monitors EGT and sends an appropriate indication to the cockpit display in case of exceedance of the limit.
The FADEC unit also provides surge recovery.
The FADEC prevents inadvertent overboosting of the expected rating (EPR limit and EPR target) during power setting.
It also prevents exceedance of rotor speeds (N1 and N2) and burner pressure limits. In addition, the FADEC unit monitors EGT and sends an appropriate indication to the cockpit display in case of exceedance of the limit.
The FADEC unit also provides surge recovery.
(2) Description
(a) Overspeed
Overspeed protection logic consists of overspeed limiting loops, for both the low and high speed rotors, which act directly upon the fuel flow command. Supplementary electronic circuitry for overspeed protection is also incorporated in the EEC. Trip signals for hardware and software are combined to activate a torque motor which drives a separate overspeed valve in the fuel metering unit to reduce fuel flow to a minimum value. The engine can be shut down to reset the overspeed system to allow a restart if desired.
Overspeed protection logic consists of overspeed limiting loops, for both the low and high speed rotors, which act directly upon the fuel flow command. Supplementary electronic circuitry for overspeed protection is also incorporated in the EEC. Trip signals for hardware and software are combined to activate a torque motor which drives a separate overspeed valve in the fuel metering unit to reduce fuel flow to a minimum value. The engine can be shut down to reset the overspeed system to allow a restart if desired.
(b) Engine surge
Engine surge is detected by a rapid decrease in burner pressure or the value of rate of change of burner pressure, which indicates that surge varies with engine power level (N2/square root of theta 2 and engine inlet pressure (P2)).
Once detected, the EEC will reset the stator vanes by several degrees in the closed direction, open the booster 7th and 10th stage bleeds, and lower the maximum Wf/Pb schedule. Recovery of burner pressure to its steady state level or the elapse of a timer will release the resets on the schedules and allow the bleeds to close.
Engine surge is detected by a rapid decrease in burner pressure or the value of rate of change of burner pressure, which indicates that surge varies with engine power level (N2/square root of theta 2 and engine inlet pressure (P2)).
Once detected, the EEC will reset the stator vanes by several degrees in the closed direction, open the booster 7th and 10th stage bleeds, and lower the maximum Wf/Pb schedule. Recovery of burner pressure to its steady state level or the elapse of a timer will release the resets on the schedules and allow the bleeds to close.
D. Power Management
(1) Engine Thrust Setting Computation
The FADEC unit contains all the engine thrust setting curves to provide automatic engine thrust ratings control in Engine Pressure Ratio, (EPR) (in normal mode) and N1 (in reversionary mode).
The FADEC unit computes power management LIMIT and COMMAND parameters in EPR mode, except during reverse operation (N1 mode). These parameters are available for the following engine thrust modes:
The FADEC unit contains all the engine thrust setting curves to provide automatic engine thrust ratings control in Engine Pressure Ratio, (EPR) (in normal mode) and N1 (in reversionary mode).
The FADEC unit computes power management LIMIT and COMMAND parameters in EPR mode, except during reverse operation (N1 mode). These parameters are available for the following engine thrust modes:
- Maximum Take-Off and Go-Around
- Flexible Take-Off
- Maximum Continuous
- Maximum Climb
- Idle (no limit parameter)
- Reverse (N1 mode operation)
(a) Engine rating versus throttle position
The power management COMMAND parameter is calculated as a function of TRA such that:
The power management COMMAND parameter is calculated as a function of TRA such that:
- TRA versus rated thrust relationship is as shown on
In normal operation a forward action on the throttle resolver does not lead to a decrease in thrust. A rearward action on the throttle resolver does not lead to an increase in thrust except in reverse. - TRA versus rated thrust is consistent regardless of ambient conditions.
- TAKE-OFF/GO-AROUND ratings are always achieved at full forward throttle resolver position.
- Other ratings (MAX-CONT, MAX-CLIMB, IDLE, MAX REVERSE) are achieved at constant throttle resolver positions.
- FLEXIBLE TAKE-OFF for a given derating is achieved at constant retarded throttle resolver position.
- In normal operation there is no restriction on TRA rate of change.
Engine transient response in the Engine Pressure Ratio (EPR) and low Rotor Speed (N1) power setting modes is critically damped with minimal overshoot.
(b) Flexible take-off rating
FLEXIBLE TAKE-OFF rating is set by the assumed temperature method with the possibility to insert an assumed temperature value higher than the maximum one certified for engine operation to provide for the maximum derate allowed by the certifying Authorities.
The FADEC unit permits:
FLEXIBLE TAKE-OFF procedure with constant retarded throttle resolver position, allowing the application of full TAKE-OFF power at full forward position if selected. At this given retarded throttle resolver position, the FADEC unit thrust setting is such that thrust obtained all along the FLEXIBLE TAKE-OFF at T1 ambient temperature, and with TA assumed temperature, is the same as thrust obtained during MAXIMUM TAKE-OFF at an actual ambient temperature of TA.
FLEXIBLE TAKE-OFF rating is set by the assumed temperature method with the possibility to insert an assumed temperature value higher than the maximum one certified for engine operation to provide for the maximum derate allowed by the certifying Authorities.
The FADEC unit permits:
FLEXIBLE TAKE-OFF procedure with constant retarded throttle resolver position, allowing the application of full TAKE-OFF power at full forward position if selected. At this given retarded throttle resolver position, the FADEC unit thrust setting is such that thrust obtained all along the FLEXIBLE TAKE-OFF at T1 ambient temperature, and with TA assumed temperature, is the same as thrust obtained during MAXIMUM TAKE-OFF at an actual ambient temperature of TA.
(c) Reverse
The FADEC unit controls thrust rating during thrust reverser operation.
Engine power is set automatically by the FADEC unit to the level required for correct deploying and restowing operations in all ambient conditions. Maximum reverse power is obtained at a unique throttle control lever position (maximum rearward) and is automatically limited.
Reverser selection logic is based on throttle control lever positions and aircraft discrete information.
During reverser transit, the power setting command is limited as a function of reverser position and throttle control lever resolver position as shown in
When reverser is fully deployed or fully restowed, the FADEC unit follows throttle control lever demand.
In case of an inadvertent deployment (sensed movement greater than 10 percent of actuator full deploy travel), the EEC will execute an auto-restow
In case of an inadvertent stowing (sensed movement greater than 10 percent of actuator full stow travel), the EEC will execute an auto-redeploy
If the reverser inadvertent travel exceeds 15 percent of its travel from the fully stowed position, the EEC will command idle power. If reverser inadvertent travel exceeds 22 percent of its travel from the fully deployed position, the EEC will command idle power
The FADEC unit controls thrust rating during thrust reverser operation.
Engine power is set automatically by the FADEC unit to the level required for correct deploying and restowing operations in all ambient conditions. Maximum reverse power is obtained at a unique throttle control lever position (maximum rearward) and is automatically limited.
Reverser selection logic is based on throttle control lever positions and aircraft discrete information.
During reverser transit, the power setting command is limited as a function of reverser position and throttle control lever resolver position as shown in
When reverser is fully deployed or fully restowed, the FADEC unit follows throttle control lever demand.
In case of an inadvertent deployment (sensed movement greater than 10 percent of actuator full deploy travel), the EEC will execute an auto-restow
In case of an inadvertent stowing (sensed movement greater than 10 percent of actuator full stow travel), the EEC will execute an auto-redeploy
If the reverser inadvertent travel exceeds 15 percent of its travel from the fully stowed position, the EEC will command idle power. If reverser inadvertent travel exceeds 22 percent of its travel from the fully deployed position, the EEC will command idle power
(2) Thrust Setting
(a) General
Two thrust setting modes are available, the autothrust mode and the manual mode. The mode selection depends on throttle control lever position and on the autothrust activation/deactivation logic.
Throttles control levers move over a sector divided into three areas where autothrust system (ATHR) can be activated or not
Two thrust setting modes are available, the autothrust mode and the manual mode. The mode selection depends on throttle control lever position and on the autothrust activation/deactivation logic.
Throttles control levers move over a sector divided into three areas where autothrust system (ATHR) can be activated or not
- In the rear region (from 5 up to and excluding 4) ATHR cannot be activated.
- In the middle region (from and including 4 up to and including 2) ATHR can be activated.
- In the forward region (from 2 to 1) ATHR cannot be activated.
TAKE-OFF and FLEX TAKE-OFF shall be performed manually.
The thrust setting general arrangement is given on
(b) ATHR activation/deactivation
The autothrust function (ATHR) can be engaged or active. The engagement logic is done in the Flight Management Computer (FMGC) and the activation logic is implemented into the EEC. The activation logic in the EEC 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 control lever.
The ATHR function is engaged automatically in the FMGC by auto pilot mode demand and manually by action on the ATHR pushbutton located on the Flight Control Unit (FCU).
The ATHR de-activation and ATHR disengagement are achieved by action on the disconnect pushbutton located on the throttle control levers or by pressing 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 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 (pilot's action 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:
0 less than or equal to TLA less than MCT or (TLA = MCT and selected mode different from FLEXTO) or Alpha Floor condition
and - FCU discretes set to 1
ATHR active = 1
ATHR engaged = 1
and - Deactivation condition is not present.
The autothrust function (ATHR) can be engaged or active. The engagement logic is done in the Flight Management Computer (FMGC) and the activation logic is implemented into the EEC. The activation logic in the EEC 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 control lever.
The ATHR function is engaged automatically in the FMGC by auto pilot mode demand and manually by action on the ATHR pushbutton located on the Flight Control Unit (FCU).
The ATHR de-activation and ATHR disengagement are achieved by action on the disconnect pushbutton located on the throttle control levers or by pressing 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 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 (pilot's action 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:
0 less than or equal to TLA less than MCT or (TLA = MCT and selected mode different from FLEXTO) or Alpha Floor condition
and - FCU discretes set to 1
ATHR active = 1
ATHR engaged = 1
and - Deactivation condition is not present.
(c) 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
A forward action of 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.
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
A forward action of 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. By receiving the throttle control lever position signal, the FADEC computes permanently thrust limit ratings, shall select the corresponding limit value and send it to the cockpit.
Thrust limit mode selection shall be achieved by manually setting the throttle control lever to the corresponding unique position
On the ground, as soon as the FADEC is powered "ON" (engine not running), it shall be possible to read the computed thrust limit parameter values on the upper ECAM DU by positioning the throttle control lever on the various unique positions. (Including flex take-off condition).
On the ground, as soon as the engine is running, the computation of the thrust limit parameter is initialized in MTO/GA mode.
Throttle control lever is used as a rating mode selection device. By receiving the throttle control lever position signal, the FADEC computes permanently thrust limit ratings, shall select the corresponding limit value and send it to the cockpit.
Thrust limit mode selection shall be achieved by manually setting the throttle control lever to the corresponding unique position
- MAX CLIMB rating on position 3.
- MAX CONTINUOUS rating on position 2.
- MAX TAKE-OFF/GO-AROUND rating on position 1 (MTO/GA).
| ----------------------------------------------------------------------------- |
| A/C !ENGINE !DERATE! TRA ! -38 ! -8.23 ! 5.75 ! 51.5 ! 69.67 ! 85.5 ! |
| ! ! ! !deg. !deg. !deg. !deg. !deg. !deg. ! |
| STATUS!STATUS !STATUS! TLA ! -20 ! -4.22 ! 3.03 ! 27.11 ! 36.67 ! 45 ! |
| ! ! ! !deg. !deg. !deg. !deg. !deg. !deg. ! |
| ----------------------------------------------------------------------------! |
| ON !RUNNING! NO !BIT STATUS! 110 ! 101 ! 101 ! 101 ! 101 ! ! |
| GROUND! !DERATE!EPR OR N1 ! ! ! ! ! ! ! |
| ! ! ! LIMIT (1)! ! ! ! ! ! ! |
| ----------------------------------------------------------------------------! |
| ON ! NOT ! NO !BIT STATUS! 110 ! 010 ! 010 ! 011 ! 101 ! ! |
| GROUND!RUNNING!DERATE!EPR OR N1 ! ! ! ! ! ! ! |
| ! ! ! LIMIT (1)! ! ! ! ! ! ! |
| ----------------------------------------------------------------------------! |
| ON ! NOT ! !BIT STATUS! 110 ! 010 ! 010 ! 100 ! 101 ! ! |
| GROUND!RUNNING! FLEX !EPR OR N1 ! ! ! ! ! ! ! |
| ! ! ! LIMIT (1)! ! ! ! ! ! ! |
| ----------------------------------------------------------------------------! |
| ON ! ! !BIT STATUS! 110 ! 100 ! 100 ! 100 ! 101 ! ! |
| GROUND!RUNNING! FLEX !EPR OR N1 ! ! ! ! ! ! ! |
| ! ! ! LIMIT (1)! ! ! ! ! ! ! |
| ----------------------------------------------------------------------------! |
| ! ! NO !BIT STATUS! 110 ! 010 ! 010 ! 011 ! 101 ! ! |
| FLIGHT!RUNNING!DERATE!EPR OR N1 ! ! ! ! ! ! ! |
| ! ! ! LIMIT (1)! ! ! ! ! ! ! |
| ----------------------------------------------------------------------------! |
| ! ! !BIT STATUS! 110 ! 010 ! 010 ! 100 ! 101 ! ! |
| FLIGHT!RUNNING! FLEX !EPR OR N1 ! ! ! ! ! ! ! |
| ! ! ! LIMIT (1)! ! ! ! ! ! ! |
| ----------------------------------------------------------------------------! |
| ! !ALPHA !BIT STATUS! 101 ! 101 ! 101 ! 101 ! 101 ! ! |
| FLIGHT!RUNNING!FLOOR !EPR OR N1 ! ! ! ! ! ! ! |
| ! ! ! LIMIT (1)! ! ! ! ! ! ! |
| ----------------------------------------------------------------------------! |
| Description of Bits in Discrete Label 292 |
| (1) |
| Bit No.21 20 19 No. Definition |
| ----------------- - ---------- |
| 0 0 0 0 Invalid thrust mode (N1 unrated mode) |
| 0 0 1 1 Not used |
| 0 1 0 2 Max Climb thrust mode |
| 0 1 1 3 Max Continuous thrust mode |
| 1 0 0 4 Flex Take off |
| 1 0 1 5 Max Take off/Go-Around thrust mode |
| 1 1 0 6 Reverse thrust mode |
| 1 1 1 7 Bump |
NOTE: In case of non validation of FLEX TAKE-OFF temperature before the throttle control lever is set to the MCT detent, the FADEC will not activate FLTO. In-flight if throttle control lever is set to MCL or to TO/GA then FLTO is cancelled, and FLTO becomes MCT.
When both throttle control lever positions select two different modes the rating limits sent by the two FADECs will be different. The Auto Flight System (AFS) will take into account the highest one. On the ground, as soon as the FADEC is powered "ON" (engine not running), it shall be possible to read the computed thrust limit parameter values on the upper ECAM DU by positioning the throttle control lever on the various unique positions. (Including flex take-off condition).
On the ground, as soon as the engine is running, the computation of the thrust limit parameter is initialized in MTO/GA mode.
3 Flex take-off
On the ground, if a Flex TO temperature has been set on the MCDU of the FMS and has been validated (range, parity, SSM test...) and is higher than the static air temperature, the FADEC unit shall set 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 shall be 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 shall 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 shall be achieved by pushing the throttle control lever to the full forward stop.
On the ground, if a Flex TO temperature has been set on the MCDU of the FMS and has been validated (range, parity, SSM test...) and is higher than the static air temperature, the FADEC unit shall set 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 shall be 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 shall 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 shall be 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 shall be adjusted to the level required by the throttle control lever position through EPR CMD = f (TLA)
When the throttle control lever is positioned on one of the unique positions the commanded thrust parameter shall be the limit corresponding to this unique position.
In manual mode the actual thrust parameter controlled by the FADEC shall be adjusted to the level required by the throttle control lever position through EPR CMD = f (TLA)
When the throttle control lever is positioned on one of the unique positions the commanded thrust parameter shall be the limit corresponding to this unique position.
(d) Autothrust setting
1 General
In autothrust mode the FADEC is working with EPR CMD = EPR target from the AFS, taking into account that the EPR CMD will be always limited by the EPR throttle.
In autothrust mode the FADEC is working with EPR CMD = EPR target from the AFS, taking into account that the EPR CMD will be always limited by the EPR throttle.
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 EPR target demand equal to EPR MAX TAKE-OFF.
When receiving alpha floor protection signal through ARINC 429 data bus, the FADEC switches EPR target limitation from EPR throttle = f (TLA) to EPR MAX TAKE-OFF for any throttle control lever position.
The alpha floor function can only be overridden by pilot's action on the ATHR system disconnect switches located on the throttle control levers.
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 EPR target demand equal to EPR MAX TAKE-OFF.
When receiving alpha floor protection signal through ARINC 429 data bus, the FADEC switches EPR target limitation from EPR throttle = f (TLA) to EPR MAX TAKE-OFF for any throttle control lever position.
The alpha floor function can only be overridden by pilot's action on the ATHR system disconnect switches located on the throttle control levers.
3 Memo thrust setting
When ATHR is deactivated, there are some cases where the thrust is frozen to the actual value see 5.B. (2) in that case the thrust is set accordingly to the logic shown on
When ATHR is deactivated, there are some cases where the thrust is frozen to the actual value see 5.B. (2) in that case the thrust is set accordingly to the logic shown on
(1) General
There are two modes of starting control associated with two different procedures and corresponding to two engine starting logics in the EEC
There are two modes of starting control associated with two different procedures and corresponding to two engine starting logics in the EEC
(a) Automatic starting logic under the full authority of the FADEC system.
The FADEC initiates the automatic sequence of command to:
The FADEC initiates the automatic sequence of command to:
- pneumatic starter valve opening and closing
- HP fuel valve
- igniters.
- engine limits protection N1, N2, EGT
- on ground start abort in case of detected incident (hot start, stall, failure to light, hung start)
- in flight start, only fault indication, without automatic start abort
- specific fault message transmission.
(b) Alternate start logic with authority of the FADEC limited to:
- actuation of the pneumatic starter valve, through the activation of the MAN START pushbutton switch and the setting of the ENG/MODE/CRANK/NORM/IGN START to IGN START.
- energization of the spark igniter and setting of the ENG/MASTER control switch to ON to energize the HP fuel shut off valve.
- Stop of the ignition and starter air valve.
- generation of warning indications.
A passive survey of the engine is provided during start without authority to abort it.
(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 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 in ignition position, the FADEC opens the pneumatic starter valve and a dry crank sequence of 30s is performed when the MASTER control switch is switched to ON
- then the FADEC switches the igniter ON and opens the HP fuel shut off valve
- at N2 = 43 percent rpm the FADEC closes the pneumatic starter valve and deenergizes the igniter
- then the FADEC controls the fuel according to the start fuel schedule
- in case of ignition delay, the FADEC will automatically operate both igniters and will provide information to the DMC
- for an airstart the FADEC identifies windmilling or starter assist conditions
- in case of failure of the 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 control switch to the OFF position.
This action initiates:
Interruption of automatic start is possible by selection of the ENG/MASTER control switch to the OFF position.
This action initiates:
- direct closure of the HP fuel shut off valve
- pneumatic starter valve closure via the FADEC
- de-energization of the igniters.
(c) Start abort
1 On the ground
Start abort by the FADEC is automatic in case of detected incident such as:
Start abort by the FADEC is automatic in case of detected incident such as:
- hot start,
- no ignition,
- start stall.
2 In flight
The FADEC provides the same monitor as on ground with fault indication but the start abort is manual only.
The FADEC provides the same monitor as on ground with fault indication 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 MAN START signal.
The FADEC operating sequence is as follows:
The FADEC has the capability to perform alternative start, after reception of the MAN START signal.
The FADEC operating sequence is as follows:
- with the ENG/MODE/CRANK/NORM/IGN START selector switch in the IGN/START position, the FADEC opens the pneumatic starter valve when it receives the MAN START signal and an automatic dry crank sequence of 30s is performed.
- then the ENG/MASTER control switch is switched to ON, the FADEC opens the HP fuel shut off valve and energizes igniter.
- when N2 reaches 43 percent rpm the FADEC closes the starter valve and de-energizes the igniter
- 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 as in automatic start and provides the same warning indications but the starting interruption is under manual control.
- in alternate mode the FADEC performs the same monitoring as in automatic start and provides the same warning indications but the starting interruption is under manual control.
(b) Start interruption
Interruption of the alternative start is possible:
Interruption of the alternative start is possible:
- before the MASTER control switch is set to ON, by switching the MAN START pushbutton switch to OFF.
- after the MASTER control switch is set to ON, by switching first the MAN START pushbutton switch to OFF and then the MASTER control switch to OFF.
(4) Engine Shut off
If the MASTER control 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 below N2 idle speed.
The direct signal from the cockpit has always priority over the FADEC for shutting the engine down even if the FADEC commands the HP fuel shut off valve open.
If the MASTER control 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 below N2 idle speed.
The direct signal from the cockpit has always priority over the FADEC for shutting the engine down even if the FADEC commands the HP fuel shut off valve open.
(5) Engine Flame-out
The FADEC will detect an engine flameout and automatically attempt a relight. This procedure will select dual ignition and send the corresponding message for cockpit display. If the attempt to relight is unsuccessful, the FADEC will identify engine condition, command the restart conditions, and send a message for cockpit display.
The FADEC will detect an engine flameout and automatically attempt a relight. This procedure will select dual ignition and send the corresponding message for cockpit display. If the attempt to relight is unsuccessful, the FADEC will identify engine condition, command the restart conditions, and send a message for cockpit display.
(6) Dry Crank
Dry crank can be selected manually from the cockpit starting panel or automatically by the FADEC when starting sequence is aborted by the FADEC.
Manual cranking is selected by:
This can be interrupted manually at any time by positioning the ENG/MASTER control switch to OFF.
Dry crank can be selected manually from the cockpit starting panel or automatically by the FADEC when starting sequence is aborted by the FADEC.
Manual cranking is selected by:
- ENG/MODE selector switch in CRANK position
- MAN start pushbutton switch set to ON.
- MAN START pushbutton switch set to OFF.
This can be interrupted manually at any time by positioning the ENG/MASTER control switch to OFF.
(7) Wet Crank
Wet crank can only be performed manually, it is selected by:
Selection of the ENG/MASTER control switch to OFF (manual start left ON) leads to dry crank.
Wet crank can only be performed manually, it is selected by:
- ENG/MODE selector switch in CRANK position,
- MAN START pushbutton switch set to ON,
- ENG/MASTER control switch set to ON position.
Selection of the ENG/MASTER control switch to OFF (manual start left ON) leads to dry crank.
(8) Igniter Selection/Continuous Ignition Selection
The FADEC automatically alternates the igniter used for each start.
The FADEC automatically selects continuous ignition when:
The FADEC automatically alternates the igniter used for each start.
The FADEC automatically selects continuous ignition when:
- the ENG/MODE selector switch is turned to IGN/START while the engines are at or above idle,
- flameout is detected,
- airstart is performed,
- takeoff (determined by TRA) or flex takeoff is performed,
- engine anti-ice is selected,
- EIU fails (except during cranking),
- EEC receives a failed rotory selector position input from the EIU,
- approach idle is selected,
- Master Lever is inadvertently cycled from ON to OFF then back to ON position.
F. Engine Parameter Transmission for Cockpit Display
The FADEC provides the necessary engine parameters for cockpit display through the ARINC 429 data bus outputs.
The FADEC provides the necessary engine parameters for cockpit display through the ARINC 429 data bus outputs.
G. Engine Condition Parameter Transmission
Engine Condition monitoring is provided by the ability of the FADEC to transmit the engine parameters through the ARINC 429 data bus output.
The basic engine parameters available are:
Engine Condition monitoring is provided by the ability of the FADEC to transmit the engine parameters through the ARINC 429 data bus output.
The basic engine parameters available are:
- WF, N1, N2, P5, PB, Pamb T4.9 (EGT), P2, T2, P3 and T3.
- VSV, BSBV, 7th and 10th stage bleed commanded positions HPT/LPT ACC, HPT cooling, WF valve or actuator position
- status and maintenance words, engine serial number and position.
H. FADEC System Maintenance
(1) Fault Detection
The FADEC maintenance is facilitated by internal extensive Built in Test Equipment (BITE) providing efficient fault detection.
The results of this fault detection are contained in status and maintenance words according to ARINC 429 specification and are available on the output data bus.
The FADEC maintenance is facilitated by internal extensive Built in Test Equipment (BITE) providing efficient fault detection.
The results of this fault detection are contained in status and maintenance words according to ARINC 429 specification and are 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 60 faults during the last 64 flights legs can be recorded.
Thus, if there are less than 60 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:
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 60 faults during the last 64 flights legs can be recorded.
Thus, if there are less than 60 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 FADEC non volatile memory and, when requested, is available on an aircraft centralized maintenance display unit.
In flight fault data is stored in FADEC non volatile memory and, when requested, is available on an aircraft centralized maintenance display unit.
(4) Communication with CFDS
Ground test of electrical and electronic parts is possible from the cockpit, with engines not running and through the CFDS.
The FADEC provides engine control system self testing to detect problems at LRU level.
With the FADEC no engine ground run is necessary for trim purposes after component replacement.
Ground test of electrical and electronic parts is possible from the cockpit, with engines not running and through the CFDS.
The FADEC provides engine control system self testing to detect problems at LRU level.
With the FADEC no engine ground run is necessary for trim purposes after component replacement.
3. Component Description
A. Engine Sensors
| NOTE : The EEC uses P2 pressure and P5 pressure (from P2 and P5 sensors) |
| to calculate EPR value = P5 |
| -- |
| P2 |
(5) P2/T2 Sensor
The P2/T2 sensor is located near the 12 o'clock position of the inlet cowl. It measures total pressure and temperature in the inlet air stream of the engine forward of the engine front flange. The dual output total temperature measurement is accomplished by two resistance-sensing elements housed in the P2/T2 sensor body. Each channel of the Electronic Engine Control (EEC) monitors one of these resistance elements and converts the resistance measurement to a temperature equivalent. The total gas pressure is transmitted by the pressure tubing and measured by the sensor located in channel A of the EEC. The anti-icing function of the P2/T2 sensor is provided through a heating element internally bonded to the sensor. The heater is a hermetically sealed, coaxial resistance element brazed internally to the sensor casting. Aircraft power, which is used for the heater, is switched on and off by the EEC, via the relay box.
The P2/T2 sensor is located near the 12 o'clock position of the inlet cowl. It measures total pressure and temperature in the inlet air stream of the engine forward of the engine front flange. The dual output total temperature measurement is accomplished by two resistance-sensing elements housed in the P2/T2 sensor body. Each channel of the Electronic Engine Control (EEC) monitors one of these resistance elements and converts the resistance measurement to a temperature equivalent. The total gas pressure is transmitted by the pressure tubing and measured by the sensor located in channel A of the EEC. The anti-icing function of the P2/T2 sensor is provided through a heating element internally bonded to the sensor. The heater is a hermetically sealed, coaxial resistance element brazed internally to the sensor casting. Aircraft power, which is used for the heater, is switched on and off by the EEC, via the relay box.
(6) P3/T3 Sensor
The P3/T3 sensor monitors the pressure and temperature at the exit of the HP compressor. The combined sensor houses two thermocouples and one pressure inlet port. Each thermocouple provides an independent electrical signal, proportional to the temperature, to one channel of the Electronic Engine Control (EEC).
The purpose of the P3/T3 sensor is to provide performance data to the EEC for starting and during transient and steady state operation of the engine.
The P3/T3 sensor monitors the pressure and temperature at the exit of the HP compressor. The combined sensor houses two thermocouples and one pressure inlet port. Each thermocouple provides an independent electrical signal, proportional to the temperature, to one channel of the Electronic Engine Control (EEC).
The purpose of the P3/T3 sensor is to provide performance data to the EEC for starting and during transient and steady state operation of the engine.
(7) P5 (4.9) Sensor
Pressure sensing instrumentation is incorporated in the leading edge of specific turbine exhaust case struts. Struts 4, 7 and 10 contain the pressure sensing ports. Each sensing point contains eight radial pressure sensing ports which are combined to provide an average pressure. The resulting average radial pressure value from each strut is then ducted into a manifold which provides an overall turbine exhaust pressure average (P4.9). A tube from this manifold is connected to the Electronic Engine Control (EEC).
A pressure transducer located within the EEC converts the average pressure at station 4.9 into a useable electronic signal (proportional to pressure) that can be processed and used by the EEC as required to control the engine, perform fault detection, etc..
Pressure sensing instrumentation is incorporated in the leading edge of specific turbine exhaust case struts. Struts 4, 7 and 10 contain the pressure sensing ports. Each sensing point contains eight radial pressure sensing ports which are combined to provide an average pressure. The resulting average radial pressure value from each strut is then ducted into a manifold which provides an overall turbine exhaust pressure average (P4.9). A tube from this manifold is connected to the Electronic Engine Control (EEC).
A pressure transducer located within the EEC converts the average pressure at station 4.9 into a useable electronic signal (proportional to pressure) that can be processed and used by the EEC as required to control the engine, perform fault detection, etc..
(a) Description
The fuel temperature is measured by the thermocouple at the fuel exit of the FCOC (Fuel Cooled Oil Cooler).
The thermocouple is composed of stainless steel sheathed sensing portion, stainless steel installing flange with seal spigot and electrical connector.
Fuel temperature is controlled by the fuel diverter valve which is installed upstream of the FCOC.
The fuel temperature is measured by the thermocouple at the fuel exit of the FCOC (Fuel Cooled Oil Cooler).
The thermocouple is composed of stainless steel sheathed sensing portion, stainless steel installing flange with seal spigot and electrical connector.
Fuel temperature is controlled by the fuel diverter valve which is installed upstream of the FCOC.
(b) Operation
The measured temperature is transmitted to the EEC.
In response to the measured temperature, the EEC sends the signal to the fuel diverter valve. The fuel diverter valve is used to reduce the fuel temperature if it is too high. The excess of high pressure fuel flow from the FMU and return fuel from control actuator are routed to the diverter valve which normally directs the flow to the FCOC exit.
The measured temperature is transmitted to the EEC.
In response to the measured temperature, the EEC sends the signal to the fuel diverter valve. The fuel diverter valve is used to reduce the fuel temperature if it is too high. The excess of high pressure fuel flow from the FMU and return fuel from control actuator are routed to the diverter valve which normally directs the flow to the FCOC exit.
B. Dedicated Permanent Magnet Alternator (PMA)
The alternator functions as the primary power source for the EEC and transmits an N2 signal to the EEC, Engine Vibration Monitoring Unit (EVMU) and the cockpit. It comprises two stators (one power and one speed) and a rotor.
The rotor is mounted directly on the gearbox output shaft and the stator is bolted to the gearbox housing.
The alternator provides two identical and independent power outputs, one for each channel of the EEC. On one channel, an N2 speed input is obtained by the EEC by sensing the frequency of the output of the alternator.
A separate stator provides two identical frequency outputs: one is utilized by the Engine Vibration Monitoring Unit (EVMU), and the other utilized by the EEC as an N2 speed input. The ECAM system is provided with this signal as it is valid at very low speeds. The speed stator is designed to tolerate indefinite short circuit conditions.
The stator and rotor are sealed from the gearbox by a shaft seal. If a shaft seal failure occurs and the alternator fills with engine oil, the alternator will continue to function normally.
To maintain the temperature of the dedicated alternator at an acceptable level the alternator incorporates an integral cooling air manifold using fan air.
The alternator functions as the primary power source for the EEC and transmits an N2 signal to the EEC, Engine Vibration Monitoring Unit (EVMU) and the cockpit. It comprises two stators (one power and one speed) and a rotor.
The rotor is mounted directly on the gearbox output shaft and the stator is bolted to the gearbox housing.
The alternator provides two identical and independent power outputs, one for each channel of the EEC. On one channel, an N2 speed input is obtained by the EEC by sensing the frequency of the output of the alternator.
A separate stator provides two identical frequency outputs: one is utilized by the Engine Vibration Monitoring Unit (EVMU), and the other utilized by the EEC as an N2 speed input. The ECAM system is provided with this signal as it is valid at very low speeds. The speed stator is designed to tolerate indefinite short circuit conditions.
The stator and rotor are sealed from the gearbox by a shaft seal. If a shaft seal failure occurs and the alternator fills with engine oil, the alternator will continue to function normally.
To maintain the temperature of the dedicated alternator at an acceptable level the alternator incorporates an integral cooling air manifold using fan air.
C. Engine Electronic Control (EEC)
(1) General
The Electronic Engine Control is the main component of the engine fuel and control system. The EEC receives data input from the other aircraft systems and generates control signals to the engine systems and components. The EEC also monitors the systems and components to make sure they operate properly.
The Electronic Engine Control is the main component of the engine fuel and control system. The EEC receives data input from the other aircraft systems and generates control signals to the engine systems and components. The EEC also monitors the systems and components to make sure they operate properly.
(2) Description
The EEC is installed on the fan case, at the 2 o'clock location. It is attached with four brackets and four vibration-isolated bolts.
The EEC is a full-authority digital control. It has two identical electronic channels. Each channel receives aircraft and engine-supplied data, including:
The EEC controls these engine functions:
The EEC uses identical software in each of the two electronic channels. Each of the two channels has a processor, power supply, program memory and input/output function.
This provides redundancy for the engine control system.
The mode of operation and the selection of the channel in control results from availability of input signals and output controls. Each channel normally uses its own input signals. Each channel can also use signals from the other channel.
The primary mode of operation is a closed-loop control using Engine Pressure Ratio (EPR). If sufficient input signals are not available to operate in this mode, the EEC changes to closed-loop control using N1 speed (Ref. Chapter 3.A.).
Selection of the channel in control results from the ability to control the most important outputs and condition of the processor and power supply.
The output devices use hydraulic, pneumatic, and electrical sources of power. Torque motors and solenoids use redundant coils. Feedback devices such as resolvers, Linears Variable Directional Transducers (LVDTs), and Rotary Variable Directional Transducers (RVDTs) are redundant, with one provided for each channel of the EEC. The EEC is shielded and grounded to prevent damage caused by lightning.
The EEC is installed on the fan case, at the 2 o'clock location. It is attached with four brackets and four vibration-isolated bolts.
The EEC is a full-authority digital control. It has two identical electronic channels. Each channel receives aircraft and engine-supplied data, including:
- throttle position,
- total air pressure,
- total air temperature,
- pressure altitude,
- rotor speeds,
- Exhaust Gas Temperature (EGT),
- aircraft digital data.
The EEC controls these engine functions:
- acceleration and deceleration limits,
- Engine Pressure Ratio (EPR),
- isochronous idle speed governing,
- overspeed limits (N1 and N2),
- fuel flow,
- compressor stator vane angle,
- compressor bleed systems,
- turbine cooling air,
- air-cooled and fuel-cooled oil coolers,
- active clearance control system,
- thrust reverser,
- automatic start of the engine.
- fuel on/off solenoid,
- starter pneumatic valve,
- ignition relay box,
- thrust reverser control solenoids (2).
The EEC uses identical software in each of the two electronic channels. Each of the two channels has a processor, power supply, program memory and input/output function.
This provides redundancy for the engine control system.
The mode of operation and the selection of the channel in control results from availability of input signals and output controls. Each channel normally uses its own input signals. Each channel can also use signals from the other channel.
The primary mode of operation is a closed-loop control using Engine Pressure Ratio (EPR). If sufficient input signals are not available to operate in this mode, the EEC changes to closed-loop control using N1 speed (Ref. Chapter 3.A.).
Selection of the channel in control results from the ability to control the most important outputs and condition of the processor and power supply.
The output devices use hydraulic, pneumatic, and electrical sources of power. Torque motors and solenoids use redundant coils. Feedback devices such as resolvers, Linears Variable Directional Transducers (LVDTs), and Rotary Variable Directional Transducers (RVDTs) are redundant, with one provided for each channel of the EEC. The EEC is shielded and grounded to prevent damage caused by lightning.
(3) Power Supply
Electrical power for the EEC is supplied by an alternator.
The alternator is driven by the engine gearbox.
The alternator has two independent windings, one for each channel of the EEC.
28VDC power is used to supply:
Electrical power for the EEC is supplied by an alternator.
The alternator is driven by the engine gearbox.
The alternator has two independent windings, one for each channel of the EEC.
28VDC power is used to supply:
- the EEC for auto start on the ground,
- the reverser,
- the start control in flight,
- the EEC (as an alternative to the alternator in flight).
(4) Test
The EEC has extensive self-test and fault isolation logic. This logic operates continuously to detect and isolate the faults in the EEC and associated systems.
The EEC has extensive self-test and fault isolation logic. This logic operates continuously to detect and isolate the faults in the EEC and associated systems.
D. Fuel Metering Unit (FMU)
The Fuel Metering Unit (FMU) provides fuel flow control for all operating conditions. Variable fuel metering is provided by the FMU through EEC commands, by a torque motor controlled servo drive. Position resolvers provide feedback to the EEC. The FMU has provision to route excess fuel above engine requirements to the fuel diverter valve through the bypass loop.
A separate overspeed valve is installed in series with the main metering valve. The overspeed system reduces engine fuel flow to a minimum value in the event of an overspeed, as detected by the EEC. Overspeed valve position indication is provided to the EEC. The overspeed control is actuated by a dual coil torque motor. A fuel shutoff valve, independent from the main metering valve and the overspeed control valve, is provided in the FMU. When closed, the valve shuts off the fuel of the combustion system and unloads the fuel pump by connecting the high pressure fuel to the high pressure pump inlet. The shutoff valve is controlled by a 28 volt DC powered torque motor.
Indication of the shutoff valve position is provided as a digital signal to the EIU from the EEC.
The FMU also provides fuel hydraulic pressure to all the fuel hydraulic system external actuators. These include the BSBV system actuators, stator vane actuator, return-to-tank valve, ACOC air valve and HPT/LPT ACC valve. Each modulated actuator is controlled by a pilot valve positioned by an EEC signal to a torque motor. Low pressure return fuel from the actuators is sent to the fuel diverter valve.
During start-up, a on/off servo valve automatically shuts off control flow to the external devices to minimize fuel pump requirements at low speed. The servo valve is switched on after receiving a fuel pressure signal from the diverter valve indicating adequate fuel capacity in the bypass loop.
The Fuel Metering Unit (FMU) provides fuel flow control for all operating conditions. Variable fuel metering is provided by the FMU through EEC commands, by a torque motor controlled servo drive. Position resolvers provide feedback to the EEC. The FMU has provision to route excess fuel above engine requirements to the fuel diverter valve through the bypass loop.
A separate overspeed valve is installed in series with the main metering valve. The overspeed system reduces engine fuel flow to a minimum value in the event of an overspeed, as detected by the EEC. Overspeed valve position indication is provided to the EEC. The overspeed control is actuated by a dual coil torque motor. A fuel shutoff valve, independent from the main metering valve and the overspeed control valve, is provided in the FMU. When closed, the valve shuts off the fuel of the combustion system and unloads the fuel pump by connecting the high pressure fuel to the high pressure pump inlet. The shutoff valve is controlled by a 28 volt DC powered torque motor.
Indication of the shutoff valve position is provided as a digital signal to the EIU from the EEC.
The FMU also provides fuel hydraulic pressure to all the fuel hydraulic system external actuators. These include the BSBV system actuators, stator vane actuator, return-to-tank valve, ACOC air valve and HPT/LPT ACC valve. Each modulated actuator is controlled by a pilot valve positioned by an EEC signal to a torque motor. Low pressure return fuel from the actuators is sent to the fuel diverter valve.
During start-up, a on/off servo valve automatically shuts off control flow to the external devices to minimize fuel pump requirements at low speed. The servo valve is switched on after receiving a fuel pressure signal from the diverter valve indicating adequate fuel capacity in the bypass loop.
E. Ignition Boxes
They are powered with aircraft 115VAC - 400Hz through the EIV and the FADEC.
The igniter A is powered from the emergency bus and the igniter B is powered from the normal bus.
They are powered with aircraft 115VAC - 400Hz through the EIV and the FADEC.
The igniter A is powered from the emergency bus and the igniter B is powered from the normal bus.
F. Pneumatic Starter Valve
The FADEC controls the opening/closing of the valve and receives the open/not open signal from the valve.
The FADEC controls the opening/closing of the valve and receives the open/not open signal from the valve.
H. VSV Feedback Signal
The FADEC receives a VSV position feedback signal from the VSV actuator.
The FADEC receives a VSV position feedback signal from the VSV actuator.
I. BSBV Feedback Signal
Same as VSV feedback signal.
Same as VSV feedback signal.
J. HP Turbine Cooling Controlled Air System Feedback Signal
The FADEC receives a position feedback signal from the control valve.
The FADEC receives a position feedback signal from the control valve.
K. HPT/LPT ACC Feedback Signal
Same as HP turbine cooling system feedback signal.
Same as HP turbine cooling system feedback signal.