Plug type :
5A / 5B differentiation : 5A and 5B ECU’s are identical.
Previous, or new connector :
Only the new type allows serial number programming through the MCDU.
EFG
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CTC-201-010-02
EFFECTIVITY
73-21-60 Page 11
ALL CFM56-5B ENGINES FOR A319-A320-A321
ENGINE SYSTEMS Jan 03
CFMI PROPRIETARY INFORMATION
EFG
ELECTRONIC CONTROL UNIT
Coding circuit.
Push-pull links :
Push-pull links provide the ECU with configuration information. They consist of switch mechanisms located between
2 contacts and can be manually opened, or closed, according to customer requests.
5B and 5B/P Differentiation :
‘/P’ stands for Performance package and /P models feature some hardware improvements, such as :
-3D design HPC blades and vanes.
- Transient Bleed Valve (TBV), deletion of the HPC clearance control function (RAC).
-3D design HPT blades and nozzles.
-HPT shroud support modified to improve flow path sealing.
-3D design LPT blades and vanes.
CFM56-5B TRAINING MANUAL
Engine type :
5B engines are equipped either with Single Annular Combustor (SAC), or Double Annular Combustor (DAC).
DAC technology focuses on a new compact combustor design with the objective of lowering the combustion gas temperature and residence times, both of which affect NOx levels.
The design incorporates two annular combustor chambers each with 20 domes (20 pilot, 20 main).
By distributing fuel to the most appropriate dome ring within the combustor, minimum NOx levels are obtained at all power settings during a typical flight cycle (idle, take off, climb, cruise, descent, landing, reverse).
Note: Various DAC type combustion chambers are available in terms of hardware and fuel distribution logic.
EFG
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CTC-201-011-02
EFFECTIVITY
73-21-60 Page 13
ALL CFM56-5B ENGINES FOR A319-A320-A321
ENGINE SYSTEMS Jan 03
CFMI PROPRIETARY INFORMATION
CFM56-5B TRAINING MANUAL
EFG
ELECTRONIC CONTROL UNIT
Coding circuit.
N1 trim level :
Engine built-up tolerances create thrust differences between engines operating at the same N1.
The ECU uses the N1 discrete modifier to reduce the thrust differences between individual engines.
The N1 command is reduced within the ECU, and this reduces the N1 actual speed by a certain percentage. Since N1 speed equals thrust, different thrust outputs can be matched.
The N1 modifier level that reduces N1, does not affect the value sent to the flight deck for display, and so, the flight deck N1 indication remains unaffected.
N1 trim levels (or modifiers) are determined during the test cell run and the N1 trim is only active beyond MCT setting.
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