Power Plant (CFM 56-5B)

The first part deals with the engine built up engine unit equipment, the CFM56-5B is designed in four major modules, which are:

1. The Fan and LP Compressor module.2. The HP Compressor, combustion chamber and HP Turbine

module3. The LP Turbine & Turbine rear frame module4. The Accessory gearbox module, where the different accessories

are installed.

Let see the location of these accessories. First, on the front face of the AGB we can identify the lubrication unit, the engine driven hydraulic pump, the ECU alternator, notice the location of the hand cranking drive pad used during the boroscope inspection and the Integrated Drive Generator (IDG).

Now on the Accessory gearbox rear face we can identify: the air startor, the fuel pump assembly and the N2 speed sensor. Again the fuel pump assembly unit with the Hydro Mechanical Unit (HMU)

The fan which produces the most of thrust consists of 36 fan blades made of titanium alloy, an abraidable lining ensures fan blade tip clearance improve efficiency, here between the fan blades we can see the inlet guide vanes of the LP Compressor.

A fan blade can be easily changed in line maintenance after removing the spinner cone assembly, the rear spinner cone is fitted with trim balance screws, a reference dent marks the blade number 1.

In the engine inlet, are located the temperature and pressure sensors related to aerodynamic station 12, which are the PS12 pressure sensors which are located at 1, 4 and 8 O’clock positions and T12 temperature sensor located at the 11 O’clock position. Now we continue with the components located at the right hand fan case, the Electronic Control Unit (ECU) of the FADEC system is installed at this zone, it has 3 main sides. On the left hand side all the pressure lines from the different pressure sensors enter directly into a pressure transmitter receptacle heart of the ECU, one of these entry ports is open because it corresponds to P0 pressure sensor.

On the bottom side, there are all the electrical harness connectors for channels A and B, two of these connectors are for a specific

requirements, one is used for engine identification plug and the second for the connection of the test equipments. Note that the engine identification plug remains on the engine when the ECU is removed, this plug contains data characteristics, engine serial number, maximum thrust take-off and etc. the same characteristics that can be read on the engine data plate.

On the right side of the ECU as the ECU is air cooled the computer is fitted with a cooling air inlet and inlet and outlet interfaces, concerning the electrical power supply the FADEC, the ECU has its own dedicated alternator located at the AGB front face.

Located above the ECU, we find the ignition boxes, the two ignition boxes are related to ignition 1 and ignition 2 circuits. Each box is designed to deliver high voltage to the ignition plugs through ignition leads, precautions have to be taken before working on the ignition boxes, the voltage output could be dangerous. The ignition leads are then routed up to the ignition plugs. The part of the ignition lead along the engine core zone is fan air cooled, the air is then discharged at the ignition plug coupling nut through a cooling shroud. There are 2 ignition plugs (igniters), one on the right hand side of the engine the 4 O’clock position corresponding to system A and one at the left hand side of the engine at the 8 O’clock position corresponding to system B.

Now lets see the engine starting components, a pneumatic start valve is installed on the duct valve going to pneumatic start valve going to the pneumatic starter located in the AGB. The start valve which is electrically controlled and pneumatically operated has a manual override handle to manually operate the valve during abnormal starts, before operating the manual override handle the operator has to press a wrench button to release the butterfly valve actuator, the manual override handle can also be used as external visual indicator to verify the position of the butterfly. Note only operate the manual override handle with starter system pressurized, otherwise you may damage the valve.When looking at the pneumatic starter we can identify the servicing ports and the v-clamp installation.

Now let see the engine vibration components, all the engine vibration parameters are collected through a remote charge convertor, this convertor then sends the vibration signals to the Engine Vibration Monitoring Unit (EVMU). There are 2 vibration sensors on the engine, one is installed on the LP Compressor module one the no1 bearing support it is called the No. 1 bearing vibration sensor, only its connector is visible from outside on the right hand fan case and the second located on the Turbine rear frame is used as a back-up

accelerometer in case of failure of No. 1 engine vibration sensor, which is not line replaceable. This second accelerometer is also used with the first one for balancing purposes.For engine speed indicating and monitoring 2 speed sensing are provided on the engine. The 1 located on the right hand side of the fan case is the N1 Speed Sensor which is sensed at the No2 bearing compartment, and the second located on the AGB rear face is for the N2 speed, each of these speed sensors has three connectors (chA, chB and EVMU).

Now lets continue with the components located at the right hand side of the engine core but first of all have a look the fan discharge casing, when looking forward we can see the struts and the fan outlet guide vanes outlet. For boroscope inspection of the LP Compressor 2 open holes are provided at the fan duct panels located at approximately the 4 O’clock position.

The HP compressor inlet temperature is monitored by the T25 sensor located at the fan frame compressor case. On the HP Compressor case, the engine is equipped with a variable stator vane system for compressor airflow control. The compressor stator vanes are in four unison rings.Now when looking at the HP compressor bottom line, we can see boroscope ports, there is a boroscope port for each stage of the HP Compressor at stages 1&2, stage 3&4, stages 5&6 and stages 7, 8 and 9 which the bolts are longer and bigger.

Now we continue with the Combustion section chamber, the combustion chamber is equipped with 20 fuel nozzles and 2 ignition plugs. Fuel for combustion is fed by means of 2 fuel manifolds, each of them supplies 10 nozzles. Each fuel nozzle has a shroud drain line connected to a separated drain manifold. Note that the fuel nozzles installed at a normal place are marked with a blue caller and the fuel nozzles near the ignition plugs are marked in silver caller because they are of a wider spray type to improve lighting up.

The fuel distribution is ensured by a Burner Staging Valve installed at approximately the 6 o’clock position on the HP Compressor case, this valve either delivers fuel to 10 nozzles at a low power or to 20 nozzles at high power.

Now have a look at the combustion chamber case, where the boroscope ports are located. Four boroscope ports are located around the combuster case. 2 boroscope ports are provided around the HP Turbine case, these ports are used to inspect the HP Turbine blades,

note that the ignitor ports can be used for inspection of the HP Turbine nozzle assembly.

Right hand side of engine core, active clearance control system LPTACC valve and HPTACC VALVE, Fan air from a scope coming cowl air, for external air cooling for lp turbine4th and 9th stage for cooling or heating of the hp shroud structure. Visual open close position.

The rear center vent tube and flame arrestor, Left hand side of engine core, the RACSB valveTop of engine 2 attach mounts (FWD mount, AFT mount)For exhaust gas temperature, On the pneumatic system, 5th stage for IP pressure and 9th stage for high pressure, hp bleed valve on hp bleed duct, bleed pressure regulating valve on the common duct.

Fire detection, 2 fire sensing elements are installed for engine core, 2 more are in pylon zone and 2 other on the AGB. Fire detector responding housing.

There are 2 VSV actuator and has LVDT for position feedback. VBV for compressor airflow control. 12 VBV actuated by fuel gear motor, other 11 by flexible shaft and has RVDT for position feedback.

Fan case left hand side, fuel system components, fuel pump on AGB, it consists of 2 pumps LP and HP stages and fuel filter, with is disposable catridge type. For monitoring the fuel diff pressure switch. On the AGB the HMU is fitted with fuel pump assembly. The HMU has several torque motors and solenoid. The fuel is heated and used to cool engine oil. Part of fuel used as servo pressure by HMU to actuate of subsytems VBV, VSV, ACCs

Fuel metered from HMU and passes through fuel flow meter, then fuel is directed to combustion chamber, part of fuel used to cool IDG oil cooling. IDG oil cooler and fuel return valve located on fan case upper engine case.

Now lets continue with the engine oil system components, the engine oil is contained in the oil tank located on the fan case left hand side. Oil from the tank passes first through an anti-siphon device before entering into the lubrication unit, this anti-siphon device prevents the tank from being drained by the pressure supply pump during engine shut-down.

The lubrication unit installed on the AGB contains a supply pump for bearing and gear lubrication and four scavenge pumps for scavenge services. The lubrication unit has two filters, the main oil supply filter and the back-up filter which is used when the main oil supply filter is clogged. The main oil supply filter is disposable and the back-up filter is self-cleanable. The lubrication unit is also equipped with an oil clogging switch and oil temperature switch for indicating (ECAM), an electrical master chip detector is installed on the lubrication unit on the main return and scavenge line. In case of oil contamination by metal particles the master chip detector operates a visual pop-out indicator located just above the oil tank. The indicator is red when popped-out. In case of pop-out, four optional chip detectors have to be installed instead of scavenge screen plugs for troubleshooting. To maintain engine oil temperature within limits the scavenge oil is cooled through the main oil/fuel heat exchanger and servo fuel heater. For pressure monitoring, a low oil pressure switch and pressure transmitter are provided on the engine they are both located on the left hand side of the fan case at approximately the 09:30 O’clock position. The oil tank which is in one piece made of light aluminum casting has a total capacity of 24 US Quarts (22.7 Liters). An oil quantity transmitter is installed on it for oil quantity measurement. For servicing two ports and a sight gauge are provided. There is also a filler cap for gravity filling with a scraper drain, do not remove the filler cap immediately after engine operation, let the oil pressure decrease for a minimum of 5 minutes after engine shut-down, if you open the filler cap before the pressure decreases, hot oil may gush out and could cause severe burns. To drain the oil tank a drain plug is installed at the bottom of the tank, when the drain plug is removed an internal check valve prevents the oil from pouring out.

Now lets see the engine drain system, the systems consists of a drain collector, a drain module and a drain mast. The drain collectors has several cylinders to collect the different fluids. The collected fluids from the drain collector are then drained to the drain mast via the drain module. Four manual push to drain valves are provided from which accessory of element the leakage is coming.

The components interfacing with the aircraft systems. First, concerning fire detection, remember that fire sensing elements are also installed on the AGB, concerning the hydraulic pump installed on the AGB front face, there is a case drain filter located on the left fan case, this case drain filter has a visual pop out indicator, above the case drain filter location we find the hydraulic low pressure switch. Finally, the IDG, lets see some details, the servicing ports, over flow and pressure filling, the reset ring for manual IDG reconnection purposes, the drain plug for drainage, and for servicing the location of the oil level sight guage.

Part II

The engine periphery is enclosed by cowls which form the nacelle, the cowls assembly consists of inlet cowl, fan cowl door and thrust reversers “C” duct cowl door. Concerning the engine drains at the bottom of the nacelle we can see here the frangible drain mast which protrudes the cowl doors into the air stream. On the nacelle left hand side are located several access doors for servicing and maintenance. On the left fan cowl door there is a quick access panel for engine oil servicing. On the left thrust reverser C duct cowl door there are on each pivoting door an access panel for the thrust reverser system actuator and a lockout fairing plate for flight lock out deactivation. Between the two pivoting door is the deploy switch access door and then on the lower pivoting door are the same element on the top pivoting door.

Now lets continue with the engine air intake, on the inlet cowl are two identical air inlet scoops for fan compartment ventilation one at the top and one at the bottom. They are used to ventilate the fan compartment accessories and components, the air in taken is then discharged over board after ventilation through an air outlet grid located the bottom of the right fan cowl door. On the fan cowl door notice the position of the aerodynamic strake. Other access panels are installed on the right hand side for the reverser system and on the right hand door the air starter manual override, this panel is also used as relieve door in case of starter duct burs. Another thing we can see here is one of the hoisting points of the fan cowl door. When looking at the rear part of the pylon we can located the pylon drain

Engine Borescope Inspection

First of all a rotator kit is installed on the cranking pad near the starter for manual drive of the hp rotor. Then, to inspect the effected section, the corresponding port covers have to be removed.

The borescope removed are:

HP compressor: stage 3 – stage 4 – stage 7 and 8 – stage 9 and 10 – stage 11 and 12

HP turbine: stage 1 and 2 – stage 2 and LP turbine.

The borescope inspection requires skill and competence, when inserting the borescope probe we can examine the blades and by

turning the compressor we can detect if there are some cracks, nicks or tip damages.