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Consists of
Dedicated alternator and power supplies
Electronic control unit (ECU) - “brains”
Hydromechanical unit (HMU) - “muscle”
Sensors for control, monitoring and feedback
Cables and connectors
More than just fuel control functions
Start
Ignition
Variable geometry (VSV’s and VBV’s)
Clearance/cooling control
Reverse thrust
Fault detection
FADEC is Full Authority Digital Engine Control. It is the name given to the
most recent generation of electronic engine controls currently installed on a
variety of high-bypass turbofan engines. FADEC systems are more
responsive, more precise, and provide more capability than the older
mechanical controls. They also integrate with the aircraft on-board
electronic operating and maintenance systems to a much higher degree.
The FADEC enhanced engine is not only more powerful and efficient than
its mechanically controlled counterpart, it is simpler to operate, and easier
to maintain.
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Flight Operations Support
10 September 2005
CFM PROPRIETARY INFORMATION
Subject to restrictions on the cover or first pa ge
FADEC components
ECU: Engine Control Unit
- Containing two identical computers, designated ChA and ChB.
- Performs engine control calculations
- Monitors the engine’s condition
ENGINE SENSORS
Used for control and monitoring.
HMU: Hydro-Mechanical Unit
which converts electrical signals from the
ECU into hydraulic pressures.
Ennggiinnee Coonnttrrooll Syysstteem
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Flight Operations Support
10 September 2005
CFM PROPRIETARY INFORMATION
Subject to restrictions on the cover or first pa ge
EEC Functions:
• Performs input signal validation &
processing
• Governs the engine forward &
reverse thrust
• Performs automatic regulation
• Provides information to airplane
( N1,2 red line / EGT red line, Max
Cont, Start red line / ENG FAIL )
EEC Architecture:
• Dual channel
• Cross-channel communication
• Fault tolerant
• Dual control sensors for critical inputs
and feedback
• Dual source airplane system inputs
cross-connected to both channels
FADEC Philosophy
Ennggiinnee Coonnttrrooll Syysstteem
- FADEC is a BITE system Built In Test Equipment
- It detects and isolates failures or combinations of failures in
order to determine the channel health status and to transmit
maintenance data to the aircraft. Each channel determines its
own health status. The healthiest channel is selected as the
active channel.
- The selection is based upon the health of each channel.
Active / Stand-by channel selection is performed
- At EEC power-up and during operation.
- At every engine start if equal health status exists ,as
soon as N2>70%.
- If a channel is faulty and the channel in control is unable to
ensure one engine function, this controlled function is moved to
a fail-safe position.
Self-tested and fault tolerant
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Flight Operations Support
10 September 2005
CFM PROPRIETARY INFORMATION
Subject to restrictions on the cover or first pa ge
Active
Channel
Standby
Channel
CCDL HMU
Regulated
Engine
System
Feedback Signals
Feedback Signals
Torque motor current
Fuel Pressure
EECCUU
FADEC Philosophy
Ennggiinnee Coonnttrrooll Syysstteem
Designed with a dual-redoundant architecture
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Flight Operations Support
10 September 2005
CFM PROPRIETARY INFORMATION
Subject to restrictions on the cover or first pa ge
Input parameters selection
VALIDATION TEST PROGRAMM
Ch A
VALIDATION TEST PROGRAMM
Ch B
LOCAL VALUE
LOCAL VALUE
CCDL
Value selected:
- Average
or
- Local value
or
- Cross channel value
or
- Engine Model
(N1, N2, PS3, T25, T3, FMV,
VSV & VBV feedback position)
or
- Failsafe Position
All electrical inputs, sensors and feedback signals are dual
A lost of parameter does not generate an ECU channel change as long as the
CCDL is operative
FADEC Philosophy
Ennggiinnee Coonnttrrooll Syysstteem
26
Flight Operations Support
10 September 2005
CFM PROPRIETARY INFORMATION
Subject to restrictions on the cover or first pa ge
Ch A
Ch B
CCDL
Single sensors ( PS13, P25, T5 )
Shared sensors
( P0,PS12,PS3,EGT )
Dual sensors
( N1, N2, T12,…)
All electrical inputs, sensors and feedback signals are dual
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航空翻译 www.aviation.cn
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CFFM556 Flight Operations Support(4)
