FULL AUTHORITY DIGITAL ENGINE CONTROL (FADEC) SYSTEM - DESCRIPTION AND OPERATION

** ON A/C NOT FOR ALL

1. General

A. Fuel Controlling - Governing System

Engine Fuel and Control System - (EEC and DSU) ** ON A/C NOT FOR ALL

(1) The Electronic Engine Control (EEC) also controls components in different systems to hold oil and fuel temperatures within specified limits and increase engine performance.

(2) The EEC monitors the health of the different systems and reports this information to the aircraft in the form of maintenance messages and cockpit caution, status and warning messages if necessary.

(3) The PW1000G FADEC system provides these capabilities:

Closed loop control of engine thrust parameter (N1)
Control of engine transients and stability
Control of performance features
Control of fuel and oil temperatures
Protection of engine limits (N1, N2, Pb)
Automatically starts sequence
Control of thrust reverser
Redundancy management
Efficient communication with aircraft systems
Monitors health and engine diagnostics
Overspeed/Thrust Control Malfunction (TCM) system.

** ON A/C NOT FOR ALL

2. Component Location

Find the PMA rotor attached to the front of the main gearbox at the 7 o'clock position.
The EEC is located approximately at the 2 o'clock position attached to the fan case assembly.
The T2 probe is attached to the inlet cowl at the 1 o'clock position.
The EEC wiring harness WC10 is located on the left-hand side of the engine core.
The PMA stator is attached to the front of the main gearbox at the 8 o'clock position.
The EEC wiring harness WC11 is located on the left-hand side of the engine core.
Find the P2.5/T2.5 probe attached to the CIC at the 1 o'clock position.
Find the T3 probe attached to the diffuser case, forward of the fuel nozzles, at approximately the 1 o'clock position.
Find the PB sensor attached to the CIC bulkhead at the 10 o'clock position.
Find the EEC wiring harness (W03) attached to the left-hand side and the right-hand side of the fan case and to the left-hand side and right-hand side of the engine core.
Find the EEC wiring harness (W04) attached to the right-hand side of the fan case and to the left-hand side and the right-hand side of the engine core.
The EEC wiring harness (WF06) attached to the right-hand side of the fan case.
Find the data storage unit attached to the EEC at the 2 o'clock position on the fan case assembly.
Find the harness (WF07) attached to the right-hand side of the fan case.
Find the harness (WC08) attached to the right-hand side of the engine core.
Find the harness (WF01) attached to the right-hand side of the fan case.
Find the harness (WF02) attached to the right-hand side of the fan case.

FIN	FUNCTIONAL DESIGNATION	ZONE	ATA REF
** ON A/C NOT FOR ALL
4000KS1	EEC-1	436	71-13-00
4000KS2	EEC-2	446	71-13-00
4001KS	T2 PROBE	400	73-11-00
4011KS	WC10 HARNESS-CORE	400	73-21-55
4020EV	ROTOR - PMA, EEC	400	73-21-53
4021EV	STATOR - PMA, EEC	400	73-21-52
4072KS	HARNESS-CORE,WC11	400	73-11-00
4082KS	FUEL RETURN TO TANK MODULE	400	73-11-00
4083KS	P2.5, T2.5 PROBE	400	73-11-00
4084KS	PROBE-T3	400	73-21-25
4085KS	SENSOR - P3	400	73-11-00
4087KS	W03 HARNESS	400	73-21-68
4088KS	W04 HARNESS	400	73-21-68
4089KS	EEC WIRING HARNESS WF06	400	73-11-00
4670KS	DATA STORAGE UNIT	400	73-11-00
4093KS	EEC WIRING HARNESS WF07	400	73-11-00
4094KS	WC08 HARNESS-CORE	400	73-21-68
4217KS	HARNESS-FAN, WF01	400	73-21-61
4218KS	HARNESS-FAN, WF02	400	73-21-62

** ON A/C NOT FOR ALL

3. Component Description

A. Electronic Engine Control (EEC)

(1) The EEC controls these functions:

Starting
Monitoring of engine condition
Measurement of the fuel flow
Engine stability
Fault detection and maintenance
Electrical Power Management
Engine performance
Ignition
Heat management
Aircraft interface
Thrust reverser system
Overspeed/Overthrust (TCM) system.

(2) The EEC is installed on the fan case at the 2 o'clock position, with four bolts next to the Prognostic Health Monitoring Unit (PHMU).

(3) The cast aluminum EEC cover uses natural convection to cool.

(4) The EEC has dual electronic channels, channel A and channel B, each with its own processor, power supply, program memory, input sensors and output actuators.

(5) The EEC has four installed pads that isolate vibration, an EEC data storage unit receptacle, inter-channel communication, two pneumatic pressure ports and a ground strap for electromagnetic compatibility.

(6) The EEC uses these to improve the stable operation of the engine:

Dual channel control
Automatic fault detection
Automatic fault accommodation
Redundant inputs and outputs.

(7) When fully operational, the EEC acts in active/standby mode where all engine capabilities are controlled by one channel.

(a) Upon detection of an output failure, the EEC acts in an active/standby mode. The active/standby mode permits the EEC to switch control of the fault loop to the other channel and maintains control of the capabilities that stay in the channel given priority for that flight.

(b) Power for the EEC is supplied by the gearbox pushed Permanent Magnet Alternator (PMA).

(d) Full self-test and fault isolation logic is programmed into the EEC and used continuously. Self-test and Line Replaceable Unit (LRU) test cycles make on-wing corrections and shop maintenance easier to isolate faults in the EEC and the input and output devices.

(8) The EEC controls these redundant solenoid systems:

Overspeed solenoid in the Integrated Fuel Pump and Control (IFPC)
Starter evaluation through a speed sensor (NS)
Air starter valve controls pneumatic power to the air starter
2.8 high compressor bleed solenoids control pneumatic pressure to the bleed valve
Directional control valve solenoid controls the hydraulic pressure for the nacelle thrust reverser system
Isolation control valve solenoid isolates the hydraulic pressure for the nacelle thrust reverser system
Evaluation is determined by the strain gauge pressure sensor installed in the isolation control valve unit.

(9) The EEC controls these redundant outputs that use alternate interfaces:

On/Off command of the dual channel ignition exciter is completed by control from each channel of the FADEC.
On/Off of T2 heater is completed by a FADEC command to the airframe.

The FADEC senses current from the heater circuit by a software discrete in each channel.

(10) The EEC controls these redundant torque motor systems:

IFPC torque motor controls the measured fuel flow to the engine. Position analysis is from a dual Linear Variable Differential Transformer (LVDT).
Stator vane actuator controls the position of the variable stator vanes. Analysis is from a dual LVDT.
The 2.5 bleed valve actuator controls the position of the 2.5 bleed valve. Analysis is from a dual LVDT.
The HPT case cooling and LPT case cooling are controlled by 1 actuator. The actuator positions a valve to control fan air flow for cooling the turbine cases. A single channel LVDT is used for analysis of the actuator.
The variable oil reduction valve controls oil bypass into the gearbox. Analysis is from a dual LVDT.
The fuel/oil heat exchanger bypass valve keeps oil and fuel temperatures within the ranges that they operate in.

B. Data Storage Unit (DSU)

(1) The DSU has the subsequent purposes:

Selection of engine thrust rating
Records the engine serial number
Selection of N1 modification data
Selection of engine performance package.

(2) The DSU is installed on the EEC "A" channel cover. The DSU has a single Electronically Erasable Programmable Read-Only Memory (EEPROM) and is installed on the EEC channel A.

(3) The engine gets a correct DSU in the process of the initial test cell operation.

(4) The N1/thrust relation is compared.

(5) The DSU must remain with the engine if the EEC is replaced.

(6) The DSU is installed on the engine fan case with a lanyard.

(7) The DSU is installed on the engine fan case with a lanyard.

(8) The DSU has a hardware part number, software part number, engine serial number, N1 class and the class it is rated in stamped on it.

(9) If the DSU is not installed, the EEC will not allow the engine to start.

(10) If the DSU disconnects in flight, the EEC will use the information that is stored in the EEC memory.

(11) The engine serial number is aided by the DSU to help monitor engine condition.

C. PHMU

(1) Refer to (Ref. AMM D/O 77-31-00-00).

[Rev.10 from 2021] 2026.04.01 03:02:27 UTC