CFM56-5B TRAINING MANUAL BASIC ENGINE

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ENGINE GENERAL CONCEPT
The CFM56-5B engine is a high by-pass, dual rotor, axial
flow turbofan. It is supported by the wing pylon and
streamlined by cowlings.
Air is sucked into the intake by the fan blades and split
into two flow paths, the Primary and the Secondary.
The primary airflow passes through the inner portion of
the fan blades and is directed into a booster (LPC).
The airflow then enters a High Pressure Compressor
(HPC) and goes to a combustor. Mixed with fuel and
ignited, the gas flow provides energy to a High Pressure
Turbine (HPT) and a Low Pressure Turbine (LPT).
The secondary airflow passes through the outer portion
of the fan blades, the Outlet Guide Vanes (OGV’s) and
exits through the nacelle discharge duct, producing
approximately 80 % of the total thrust. It also plays a role
in the thrust reverser system.

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aircraft pylon
飞机外挂架

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design and operation

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ENGINE GENERAL CONCEPT

The CFM56-5B engine uses a maintenance concept
called ‘On Condition Maintenance’. This means that the
engine has no periodic overhaul schedules and can
remain installed under the wing until something important
occurs, or when lifetime limits of parts are reached.
For this reason, to monitor and maintain the health of the
engine, different tools are available, which are :
- Engine performance trend monitoring
- Borescope inspection
- Lubrication particles analysis
- Spectrometric Oil Analysis Program (S.O.A.P)
- Engine vibration monitoring system

 

borescope  管道镜

spectrometric 光谱测定的,度谱的,分光仪的,光谱仪的

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on condition monitoring

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ENGINE GENERAL CONCEPT

The CFM56-5B engine consists of two independent
rotating systems :
- The low pressure system rotational speed is
designated N1.
- The high pressure system rotational speed is
designated N2.
The engine rotors are supported by 5 bearings, identified
in manuals as numbers 1 thru 5, where No. 1 is the most
forward and No. 5 the most aft. These bearings are
housed in 2 dry sump cavities provided by the fan and
turbine frames.
Engine structural rigidity is obtained with short lengths
between two main structures (frames).
The accessory drive system uses energy from the high
pressure compressor rotor to drive the engine and
aircraft accessories. It also plays a major role in starting.

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general engine concept

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ENGINE GENERAL CONCEPT

The CFM56-5B is a modular concept design engine. It
has 17 different modules that are enclosed within three
major modules and an accessory drive module.
The 4 modules are :
- The Fan Major Module
- The Core Engine Major Module
- The Low Pressure Turbine Major Module
- The Accessory Drive Module

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modular design

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FAN SECTION
The fan section is at the front of the engine and,
downstream from the air inlet cowl, the section includes
the fan and booster module and fan frame module.
The purposes of the fan and booster are :
- to accelerate air overboard to generate thrust.
- to increase the pressure of the air directed to the
High Pressure Compressor (HPC).
After entering the air inlet cowl, the total engine airflow
passes through the fan rotor, which increases the air’s
kinetic energy.
Most of the airflow is ducted overboard producing
approximately 80 % of the total thrust. The remainder is
directed through the booster, where it is pressurized
before entering the HPC.