Dear All,
Can someone distinguish between the aircrfat engine types from its noise?
Let me give you some noise related factors in a way of giving some differences between two types of engines installed on A320/A321.
These engines are V2500 and CFM56-5A/5B.
The V2500 has different noise tone than the CFM56-5A/B. Some of differences related factors are:
1- The V2500 has different number of stages (Compressor Stages / Turbine Stages) from CFM56-5A/B.
2- There are something called noise acoustic panels installed at the inlet of engines. These panels are used to absorb the noise coming out from the engine. Also, these panels are different in shapes, sizes, and material between the V2500 and the CFM-5A/B.
3- Every Turbo Fan Engine inlet air is divided into two parts:
A) Primary Air which goes into the engine compressor stages and turbine stages through the combustion chamber. This air that cause the engine to run. This air will be exhausted outboard. B) Secondary Air that is withdrawn by the fan at the engine inlet and discharged overboard through bypassing around the main engine components and not inside the engine. At the end also the secondary air will be discharged outboard the engine to the air.
Now on the CFM56-5A/5B the exhausted primary air will be discharged seperately to the outboard from the secondary discharged air. The primary air will be discharged through component called "Center Body". On the V2500, it is different as both the primary engine air and the secondary engine air will meet together when discharged in a component called CNA - Common Nozzle Assembly.
This design gives alot of advantages for the V2500 engines. One of the important advantages is REDUCING THE NOISE. Again mixing the discharged PRIMARY AIR with SECONDAR AIR will reduce the noise or at least smoothen it.
4- Every engine type build from different materials, specifications, inlet area, outlet area, valves such as VSV - Variable Stator Valve - , VBV - Variable Bleed Valve, VBSV - Variable Boost Start Valve, number of fan blades, area size of the fan blades,....etc other than the other type of engines.
Believe me, every engine and if I can use the word TONE has different tone from another engine type BUT all engines from the same type has the SAME TONE.
I believe that what I have briefed above are so far helpful information as I also believe we can talk alot about many other factors. But I can say the above are the main factors.
B.Regards
Ayman Shak'ah
Licensed Aircraft Maint. Engineer
Tuesday, September 18, 2007
Monday, September 17, 2007
ETOPS REQUIRMENTS
Dear All,
ETOPS is "Extended Twin Engine operation". The ETOPS regulation is designed for any aircraft with twin engines.
Why and What are the ETOPS Categories??
ETOPS: This definition is agreed by the ICAO - Internation Civil Aviation Organization -.
This regulation has requirments to comply with it. They are determined by the FAA, CAA, and other NAA.
The Idea of ETOPS is to make sure that any aircraft categorized at specific ETOPS category will fly to its destination over remote land or over water at which no airport will be available through the route.
There are different ETOPS categorizations. Some of them are:
ETOPS 60 MINUTES
ETOPS 90 MINUTES
ETOPS 120 MINUTES
ETOPS 180 MINUTES
That means the aircraft as example like the one certified for ETOPS 60 minutes can fly to a distination through a route at which there will be no airport within 60 Minutes over water such as sea, ocean or over remote land.
Now maybe an aircraft has been certified as ETOPS 180 Minutes. It can be degraded by the ground engineer to ETOPS 120 minutes or even completely degraded to NON ETOPS if the engineer found it not complying to the ETOPS 180 requirments but it is still complying to ETOPS 120 Minutes.
Example for the above situation: An approved aircraft for ETOPS 120 Minutes must have All the three electrical generators operative for the next flight (Two IDGs) and one APU Electrical Generator. The aircraft received by the ground engineer with one IDG INOPERATIVE. Then the engineer will dispatch the aircraft according to the requirments as ETOPS 60 minutes or maybe will degrade the aircraft to non ETOPS.
For the many complicated factors and requirments set by the civil aviations for SAFETY REASONS and REDUNDANCY REASONS many manufacturer noted that it will be helpful to set four engines instead of two and at the same time many airline found it really advantage to use these aircraft especially for flights which need to cross the ocean.
Sometimes, it is really bad to degrade the aircraft from ETOPS to Non ETOPS as this will affect on the whole airline fleet, time, and money.
To eliminate from all of these factors, FOUR ENGINES OPERATED AIRCRAFT is better in my opinion.
B.Regards
Ayman Shak'ah
Licensed Aircraft Maint. Engineer
ETOPS is "Extended Twin Engine operation". The ETOPS regulation is designed for any aircraft with twin engines.
Why and What are the ETOPS Categories??
ETOPS: This definition is agreed by the ICAO - Internation Civil Aviation Organization -.
This regulation has requirments to comply with it. They are determined by the FAA, CAA, and other NAA.
The Idea of ETOPS is to make sure that any aircraft categorized at specific ETOPS category will fly to its destination over remote land or over water at which no airport will be available through the route.
There are different ETOPS categorizations. Some of them are:
ETOPS 60 MINUTES
ETOPS 90 MINUTES
ETOPS 120 MINUTES
ETOPS 180 MINUTES
That means the aircraft as example like the one certified for ETOPS 60 minutes can fly to a distination through a route at which there will be no airport within 60 Minutes over water such as sea, ocean or over remote land.
Now maybe an aircraft has been certified as ETOPS 180 Minutes. It can be degraded by the ground engineer to ETOPS 120 minutes or even completely degraded to NON ETOPS if the engineer found it not complying to the ETOPS 180 requirments but it is still complying to ETOPS 120 Minutes.
Example for the above situation: An approved aircraft for ETOPS 120 Minutes must have All the three electrical generators operative for the next flight (Two IDGs) and one APU Electrical Generator. The aircraft received by the ground engineer with one IDG INOPERATIVE. Then the engineer will dispatch the aircraft according to the requirments as ETOPS 60 minutes or maybe will degrade the aircraft to non ETOPS.
For the many complicated factors and requirments set by the civil aviations for SAFETY REASONS and REDUNDANCY REASONS many manufacturer noted that it will be helpful to set four engines instead of two and at the same time many airline found it really advantage to use these aircraft especially for flights which need to cross the ocean.
Sometimes, it is really bad to degrade the aircraft from ETOPS to Non ETOPS as this will affect on the whole airline fleet, time, and money.
To eliminate from all of these factors, FOUR ENGINES OPERATED AIRCRAFT is better in my opinion.
B.Regards
Ayman Shak'ah
Licensed Aircraft Maint. Engineer
Inlet Engine Fairings / Shapes / Swirl Mark
Dear All,
Alot of people in the field are always asking why the engine inlet fairings differ from engine to another?? Some of them are cones another are half ball??
What does the Swirl White Solid Line Means??
I would like to clarify this issue in a very simple way giving an example of some engine types.
On CFM56-5A/5B/5C, the engine inlet fairing looks like a cone. This cone has a specific sliding angle which is called (Anti Ice Algebric Angle). According to the studies done by the designers, they have noticed that at this specific angle of cone slide the ice will not accumulate or build up on the engine inlet cone which in some cases it may become dangerous on engine operation.
On V2500, although it is a cone, but the cone slide doesn't have Anti Ice Algebric Angle as it is more acute angle. Instead of that angle, the cone head is made of small piece made from rubber. This peice will keep vibrating while engine is running preventing engine inlet ice accumulation or build up mechanically. (REALLY SMART DESIGNERS).
On CF6-8, the engine inlet fairing isn't completely a cone. It is half ball shape and as we know on this shape, it is almost impossible to be the perfect shape for ice accumulation or build up. Now most of the Engine Inlet Fairings have swirl solid white line. This line will become like EAGLE EYE shape when the engine starts to run. This shape can be distiguished clearly by the birds. The EAGLE EYE shape will make birds frightened from coming near the engine while running and this will prevent bird ingestion or what we call (ENGINE BIRD STRIKE).
Please note that in the near future, you will find alot of photos and schematics explaining most of common questions generated by different people in the field and from passengers.
B.Regards
Ayman Shak'ah
Licensed Aircraft Maint. Engineer
Alot of people in the field are always asking why the engine inlet fairings differ from engine to another?? Some of them are cones another are half ball??
What does the Swirl White Solid Line Means??
I would like to clarify this issue in a very simple way giving an example of some engine types.
On CFM56-5A/5B/5C, the engine inlet fairing looks like a cone. This cone has a specific sliding angle which is called (Anti Ice Algebric Angle). According to the studies done by the designers, they have noticed that at this specific angle of cone slide the ice will not accumulate or build up on the engine inlet cone which in some cases it may become dangerous on engine operation.
On V2500, although it is a cone, but the cone slide doesn't have Anti Ice Algebric Angle as it is more acute angle. Instead of that angle, the cone head is made of small piece made from rubber. This peice will keep vibrating while engine is running preventing engine inlet ice accumulation or build up mechanically. (REALLY SMART DESIGNERS).
On CF6-8, the engine inlet fairing isn't completely a cone. It is half ball shape and as we know on this shape, it is almost impossible to be the perfect shape for ice accumulation or build up. Now most of the Engine Inlet Fairings have swirl solid white line. This line will become like EAGLE EYE shape when the engine starts to run. This shape can be distiguished clearly by the birds. The EAGLE EYE shape will make birds frightened from coming near the engine while running and this will prevent bird ingestion or what we call (ENGINE BIRD STRIKE).
Please note that in the near future, you will find alot of photos and schematics explaining most of common questions generated by different people in the field and from passengers.
B.Regards
Ayman Shak'ah
Licensed Aircraft Maint. Engineer
Sunday, September 16, 2007
Absolute Pressure / Gauge Pressure
Dear All,
What is the word PRESSURE means? What is the diffrence betwen the Absolute Pressure and the Gauge Pressure?
Pressure is (force per unit area - Pa or psi or mb). It Starts at 1013mb (14.7psi) at sea level and falls at a non-linear rate with altitude. Losing most of its value at the lower altitudes so that at 18,000ft, for example, the pressure is halved to 506mb).
These pressure readings are absolute pressure readings. This means that if an ordinary pressure gauge is open to atmosphere it will read zero. To illustrate the point - checking a tyre pressure with it (say 30psi) the reading will be 30psi. This is called gauge pressure of the tyre. Its absolute pressure would be gauge pressure plus atmospheric pressure = 30 + 14.7 = 44.7psi absolute.
So, in general we can say that
ABSOLUTE PRESURE = GAUGE PRESSURE + 14.7 PSI
B.Regards
Ayman Shakah
Licensed Aircraft Maint. Engineer
What is the word PRESSURE means? What is the diffrence betwen the Absolute Pressure and the Gauge Pressure?
Pressure is (force per unit area - Pa or psi or mb). It Starts at 1013mb (14.7psi) at sea level and falls at a non-linear rate with altitude. Losing most of its value at the lower altitudes so that at 18,000ft, for example, the pressure is halved to 506mb).
These pressure readings are absolute pressure readings. This means that if an ordinary pressure gauge is open to atmosphere it will read zero. To illustrate the point - checking a tyre pressure with it (say 30psi) the reading will be 30psi. This is called gauge pressure of the tyre. Its absolute pressure would be gauge pressure plus atmospheric pressure = 30 + 14.7 = 44.7psi absolute.
So, in general we can say that
ABSOLUTE PRESURE = GAUGE PRESSURE + 14.7 PSI
B.Regards
Ayman Shakah
Licensed Aircraft Maint. Engineer
Semi COnductors / Dopping
Dear All,
SEMI CONDUCTORS: they are materials which at normal state they are insulators but under certain forces like VOLTAGE, they become conductors. When this force removed, these materials return to its normal state as insulators without causing any damage to the material itself.
They - Semi Conductors - can switch to both states hundred of thousands in a second. They are used in computer hardware. The most famous materials are
1-GERMANIUM
2-SILICON
When no voltage applied, there will be few hundred to few thousands of ohms but when voltage applied, the resistance will drop to zero.
The semi-conductors will become conductors when adding impurity atoms during the growing of crystal lattice. This is called DOPPING.
B.Regards
Ayman Shak'ah
Licensed Aircraft Maint. Engineer
SEMI CONDUCTORS: they are materials which at normal state they are insulators but under certain forces like VOLTAGE, they become conductors. When this force removed, these materials return to its normal state as insulators without causing any damage to the material itself.
They - Semi Conductors - can switch to both states hundred of thousands in a second. They are used in computer hardware. The most famous materials are
1-GERMANIUM
2-SILICON
When no voltage applied, there will be few hundred to few thousands of ohms but when voltage applied, the resistance will drop to zero.
The semi-conductors will become conductors when adding impurity atoms during the growing of crystal lattice. This is called DOPPING.
B.Regards
Ayman Shak'ah
Licensed Aircraft Maint. Engineer
A320 Electrical System / Sources
Dear All,
The A320 has alot of electrical sources. They are as follow:
1- Two AC main buses. Each AC bus is energized from an IDG - Integrated Driven Generator - installed on each engine. The output values are: 115VAC / 90 KVA / Frequency 400 Hz.
2- One main AC bus is feeding something called essential bus and essential shed bus. The shed bus is connected to the equipment at which is important for the safety of the aircraft when buses are lost. When the main AC bus failed, then the another AC bus can be connected to the essential bus to feed it instead of the faulty one either automatic transfer or manual by push button when the auto logic fails.
3- The AC essential bus also can be fed by the emergency generator. This generator is hydraulically powered to give output electrical AC power to feed the AC essential bus. The generator is hydraulically powered by hydraulic pressurized either from the related hydraulic system if the blue hydraulic system pump is operative or by the RAT - Ram Air Turbine -. Note that the RAT can only turn at specific minimum speed on some A320 its 150 KNOTS on another A320 it is 100 knots or until the flaps slats extended.
4- When the RAT stop working, the AC essential bus will be fed from the batteries through a static inverter that will convert the 28 VDC into 115 VAC. So as you can see, the major equipment are connected with essential buses (AC and DC through essential transformer). This essential buses are always fed either from IDG, APU generator, CSM/G - Emergency Generator - using the RAT, and or static inverter. This will give the electrical system a very very high redundancy.
Thanks for AIRBUS.
B.Regards
Ayman Shak'ah
Licensed Aircraft Maint. Engineer
The A320 has alot of electrical sources. They are as follow:
1- Two AC main buses. Each AC bus is energized from an IDG - Integrated Driven Generator - installed on each engine. The output values are: 115VAC / 90 KVA / Frequency 400 Hz.
2- One main AC bus is feeding something called essential bus and essential shed bus. The shed bus is connected to the equipment at which is important for the safety of the aircraft when buses are lost. When the main AC bus failed, then the another AC bus can be connected to the essential bus to feed it instead of the faulty one either automatic transfer or manual by push button when the auto logic fails.
3- The AC essential bus also can be fed by the emergency generator. This generator is hydraulically powered to give output electrical AC power to feed the AC essential bus. The generator is hydraulically powered by hydraulic pressurized either from the related hydraulic system if the blue hydraulic system pump is operative or by the RAT - Ram Air Turbine -. Note that the RAT can only turn at specific minimum speed on some A320 its 150 KNOTS on another A320 it is 100 knots or until the flaps slats extended.
4- When the RAT stop working, the AC essential bus will be fed from the batteries through a static inverter that will convert the 28 VDC into 115 VAC. So as you can see, the major equipment are connected with essential buses (AC and DC through essential transformer). This essential buses are always fed either from IDG, APU generator, CSM/G - Emergency Generator - using the RAT, and or static inverter. This will give the electrical system a very very high redundancy.
Thanks for AIRBUS.
B.Regards
Ayman Shak'ah
Licensed Aircraft Maint. Engineer
Turbine Inlet Temperature - TIT SENSOR
Turbine Inlet Temperature Sensor (Engine):
The turbine engine is basically composed of different stages of compressors, combustion chamber, turbine stages. Now, when the engine is running, the air will ingested into the engine and will be compressed through the compressor stages. After that the air will enter the combustion chamber as an element for combustion to take place with the fuel. then, the discharged hot exhausted air will leave the combustion chamber under very high in both (Pressure and Temperature). This exhausted air is used to hit the turbine (High Pressure Turbine) causing them to rotate at which in turn will rotate the compressor and so on.
It is used to measure the temperature of the discharged air coming from the combustion chamber and hitting the turbine. the sensing of this temperature is very useful to control the engine operation by the computer that is used this information and according analysis the engine combustion effeciency and at the same time control the power output of the engine automatically through a computer called ECU - Engine Control Unit -. the ECU is a computer that receives different signals from different sensors and systems of the aircraft. One of these inputs is the Turbine Inlet Temperature.
Turbine Inlet Temperature Sensor (Aircondition System):
There is also a sensor called TIT sensor installed on the airconditioning pack. The aircondition system pack. This pack composed of
1- ACM - Air Cycle Machine - (FAN, Compressor, and Turbine)
2- Heat exchangers
3- Condenser
4- Reheater.
Now, the aircondition system is controlled by computer called Pack Controller and another computer called Zone Controller. Now the engine bleed air is delivered to the airconditioning packs to be conditioned both (Temperature and pressure) in the following sequence:
1- the bled air enters the pack via a pack flow valve.
2- the hot bled air enters the primary heat exchanger to be cooled little bit before entering the ACM compressor at which the air is going to be compressed so its pressure will increase.
3- the air will leave the compressor with high pressure and very high temperature due to the compression.
4- then the air will enter the main heat exchanger to be cooled. Then the air will enter the reheater to increase its temperature so we can eliminate any water particle suspended in the air before entering the turbine - The elimination of any water particle is useful to protect the turbine blades from being daamaged or corroded-. Then the turbine will cause the compressed air to extract due to giving force for the turbine to rotate. At this point the air entering the turbine will be so hot and the air leaving is so cold.
Now the computer controlling the system operation needs input to control the flow rate of air entering the packs and also to control the air entering the heat exchangers. Also the computer needs these inputs for maintenance personal analysis and to monitor the efficiency of packs.
Turbine inlet temperature sensed will be signaled to the pack controller which in turn with another sensors signals will control the aircondition system operation.
Ayman Shak'ah
Licensed Aircraft Engineer
The turbine engine is basically composed of different stages of compressors, combustion chamber, turbine stages. Now, when the engine is running, the air will ingested into the engine and will be compressed through the compressor stages. After that the air will enter the combustion chamber as an element for combustion to take place with the fuel. then, the discharged hot exhausted air will leave the combustion chamber under very high in both (Pressure and Temperature). This exhausted air is used to hit the turbine (High Pressure Turbine) causing them to rotate at which in turn will rotate the compressor and so on.
It is used to measure the temperature of the discharged air coming from the combustion chamber and hitting the turbine. the sensing of this temperature is very useful to control the engine operation by the computer that is used this information and according analysis the engine combustion effeciency and at the same time control the power output of the engine automatically through a computer called ECU - Engine Control Unit -. the ECU is a computer that receives different signals from different sensors and systems of the aircraft. One of these inputs is the Turbine Inlet Temperature.
Turbine Inlet Temperature Sensor (Aircondition System):
There is also a sensor called TIT sensor installed on the airconditioning pack. The aircondition system pack. This pack composed of
1- ACM - Air Cycle Machine - (FAN, Compressor, and Turbine)
2- Heat exchangers
3- Condenser
4- Reheater.
Now, the aircondition system is controlled by computer called Pack Controller and another computer called Zone Controller. Now the engine bleed air is delivered to the airconditioning packs to be conditioned both (Temperature and pressure) in the following sequence:
1- the bled air enters the pack via a pack flow valve.
2- the hot bled air enters the primary heat exchanger to be cooled little bit before entering the ACM compressor at which the air is going to be compressed so its pressure will increase.
3- the air will leave the compressor with high pressure and very high temperature due to the compression.
4- then the air will enter the main heat exchanger to be cooled. Then the air will enter the reheater to increase its temperature so we can eliminate any water particle suspended in the air before entering the turbine - The elimination of any water particle is useful to protect the turbine blades from being daamaged or corroded-. Then the turbine will cause the compressed air to extract due to giving force for the turbine to rotate. At this point the air entering the turbine will be so hot and the air leaving is so cold.
Now the computer controlling the system operation needs input to control the flow rate of air entering the packs and also to control the air entering the heat exchangers. Also the computer needs these inputs for maintenance personal analysis and to monitor the efficiency of packs.
Turbine inlet temperature sensed will be signaled to the pack controller which in turn with another sensors signals will control the aircondition system operation.
Ayman Shak'ah
Licensed Aircraft Engineer
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