Dear All,
For 10 years and until date, it becomes very important for Companies Managements, Employees, Decision Makers, and we can say even everyone to study the HUMAN FACTORS.
Human Factors are divided into TWO TOPICS. They are: 1) Physiology Factors. 2) Psychology Factors.
These two topics are important to understand because if someone think that they don't affect his life then he must be sure that they are going to affect others life.
How? When? Why?
I am going to explain this by giving examples on How? When? and Why?
A) Let us start with HOW? WHEN? WHY? from the physiological angle.
We must know about the human body and his senses like hearing, sight sense, smelling, touching, Tasting. These senses are very important to understand that they have functions which will affect taking decisions. Examples on these affected senses in aviation are:
1) When your eyes are affected, then the pilots, maintenance personal,..etc will take improper decisions because they are not able to see things correctly like when an engineer do his walk around for visual inspection or like pilot whe he observes the aircraft parameters during flight or while he reads the check lists,..etc.
2) When ears are affected, then the people working in aviation may make mistakes such as can't evaluate strange noise occurs during flight, or improper evaluation for a noise coming out from the engines while running, ..etc.
3) When the touch sense is affected, then and according to my experience sometimes you can evaluate internal leak for a component by feeling how hot it is after running. So, if I dont have the full ability to feel how hot a component is then I will take a decision to release back a component with internal leak existing and this will make troubleshooting harder.
4) When your smell sense is affected then I can for example see a leak below the wings and I will take a sample from it using my finger and smell it. If the smell sense is affected maybe I will think it is a water condensation and not a fuel leak.
5) If my tasting sense is affected, then maybe hydraulic will come on my lips and I lick it thinking that it is a water and not able to distinguish that it is hydraulic or poisonous material.
In Human Factor You study the human body parts and systems, how it works and what is it consists of. So, when you study it you will know how to care about it and keep it strong senses.
B) Let us start with HOW? WHEN? WHY? from the psychological angle.
All of us are humans, and we know how psycological factors affect us such as stress, environmental atmosphere, pressure, living costs, ...etc these factors will affect the way we take decisions like when you have financial problems and you are on duty flying an aircraft or repairing a component then most of your thinkings will be in your personal problem and this will reduce concentration of the brain on the procedure, safety, and how to troubleshoot.
There are something in the human factors study called DIRTY DOZEN. They are:
1) Lack of communication: like when somebody write a note for his colleague regarding an issue in doing a task. This note can be understood wrongle. So always it must be written in full details or at least without using alot of abbreviations.
2) Complacency: When you do something many times and you didn't find anything changed. then oneday you will say I have always done this check and I have never found anything wrong then I will not do it this time. VERY VERY COMMON AND DANGEROUS THINKING.
3) Lack of Knowledge: When you do something and you reach an area while doing it and you dont know how to do it. You may feel shame or afraid to say I DON'T KNOW. Then the shame will be bigger if you did it and caused a disaster.
4) Distraction: Very common factor. While you are working your mobile phone rings. You answer it and then after finishing the call you complete the job forgetting some points you must do. ALWAYS GO BACK 3 STEPS BEFOREE THE CALL.
5) Lack of Team Work: When you hate to work with someone or when you forget that all of people in the company are team then you will fail. Imagine that there are two pilots one is the captain another is the first officer. If they are not working in the cockpit as a team, be sure that in case of emergency the aircraft will crash.
6) Fatigue: Like working for many hours, not sleeping properly, all what you are thinking about is to make extra money with overtime. You think you are able and you are aware but believe me if you are honest with yourself then think how many times you have done mistakes because you didn't sleep well for days ago.
7) Lack of resources: Like having a problem on an aircraft and you need a part which is not available in your store. You may decide to disregard the problem and say "I will dispatch it". No, Ground the aircraft for sure is better.
8) Pressure: Liek when you get a call from your boss to inform you that you have to finish your job within an hour or less and you know that it takes more. Feeling afraid to lose the job. Believe me LOSE YOUR JOB IS MUCH BETTER THAN LOSING THE PEOPLE LIVES.
9) Assertiveness: A factor like when somebody brought you something to fix and he fill on you orders what to do according to his financial situation or needs of time. He orders you things just because he wants it like this and you know that it is wrong. DON'T DAMAGE YOUR STANDARDS for others to be happy.
10) Stress: Like political news. A war may happen. I will lose my job because of this war and such factors and thinkings. LIVE YOUR DAY, ALWAYS THINK THAT TOMORROW IS BETTER.
11) Lack of Awareness: When you do something always think of the consequences. Build a scenarios for what may happen if I install this here or there.
12) Norm: Like using things as equipment to reduce the time and taking short cuts that you think you are smarter than the manual or the manufacturer instructions. Sorry, you will be stupid and silly because even you succeed one or two times at the end you will fail. DONT DEPEND ON LUCK, THERE IS NO PLACE FOR LUCK IN OUR BUISINESS.
I hope you like such study and research I have done, and I hope we all are going to follow such instructions and make sure to stop doing any of the DIRTY DOZEN.
B.Regards
Ayman Shak'ah
Licensed Aircraft Maint. Engineer
Showing posts with label Airliners. Show all posts
Showing posts with label Airliners. Show all posts
Wednesday, September 19, 2007
Tuesday, September 18, 2007
Aircraft Engines Tones / Noises
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
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
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
Sunday, September 16, 2007
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
Rules For Dispatching Aircraft For Next Flight
Dear All,
I would like to brief some information regarding the basics in dispatching an aircraft for the next flight. These information are as follow:
1- When the aircraft reached the destination, the pilot will register any comments, faults, warnings, observations,that occured during his flight in the ATL - Aircraft Technical Log Book-. If he has no comment then he will write down "NIL DEFFECTS". At the same time, when the aircraft reaches to the gate, the ground engineer, technician, and or mechanic will carry out walk around, and transit check. Accordingly if he observe any finding such as leak, damage, ...etc he will also report it in the ATL.
2- The Aircraft Log Book is usually has two columns. One for the Finding where to be reported another for the engineer to write down the ACTION TAKEN.
3- There is a book called MMEL "Master Minimum Equipment List" in each aircraft. The MMEL is issued by the manufacturer and approved by the Civil Authorities like FAA, EASA, CAA, ...etc. Note that any airline can make more restrictions to what is mentioned in the MMEL but can't reduce what is already in it. In this case the MMEL will become MEL - Minimum Equipment List-.
4- The MMEL or MEL is the book that has most of the faults mentioned in. It will give the minimum requirment needed for the fault to be dispatched. Like it will mention if this fault is "GO", "NO GO", or "GO IF...". In the MEL also there will be for some faults the code "M" or "O" and or BOTH. The "O" is stated for OPERATIONAL PROCEDURE while the "M" is stated for MAINTENANCE PROCEDURE. That means if this fault occurs then the Pilots have specific procedure to carry out during aircraft operation regarding that system or flight and in "M" case that means the maintenance has procedure to do before dispatching the aircraft. Please note that MEL items are categorized in dispatchable time limitation such as maybe some faults are GO item for maximum limited number of flights another are dispatcheable for maximum number of days and some them are dispatcheable in some atmospheric conditions.
5- The captain can REJECT what the engineer is saying if he felt not convinced in such dispatchable conditions mentioned in the MEL because in some cases he believe in this atmospheric climate condition he may face the next flight as he can see in the meteorology report some troubles. Anyway he can REJECT the action taken and usually in this case this issue will be reported to the MANAGEMENT so they will advice the flight crew what to do or advice the Maintenance personal of what to do. LAST DECISION WILL BE FOR THE PILOTS as they are going to fly this aircraft.
6- there are some faults that you will not find in the MEL. like LEAK. We can find the dispatchable limitation for any leak in the AMM - Aircraft Maintenance Manual - that will state the dispatchable leak limitation and according also to the leak limitation.
7- Some findings maybe like structore damage, in this case the reference will be something called SRM "Structural Repair Manual" that will give the dispatchable measurements of that damage and always we put into consideration if this damage location in pressurized or unpressurized zones on the aircraft.
So far, I hope that this briefing clarify the way of dispatching any aircraft for the next flight. At the end of each aircraft log book page, the ground engineer, or technician, or mechanic will sign certification that the aircraft is safe for the next flight and then the CAPTAIN will sign final acceptance for that aircraft to take.
Best Regards
Ayman Shak'ah
Licensed Aircraft Maint. Engineer
I would like to brief some information regarding the basics in dispatching an aircraft for the next flight. These information are as follow:
1- When the aircraft reached the destination, the pilot will register any comments, faults, warnings, observations,that occured during his flight in the ATL - Aircraft Technical Log Book-. If he has no comment then he will write down "NIL DEFFECTS". At the same time, when the aircraft reaches to the gate, the ground engineer, technician, and or mechanic will carry out walk around, and transit check. Accordingly if he observe any finding such as leak, damage, ...etc he will also report it in the ATL.
2- The Aircraft Log Book is usually has two columns. One for the Finding where to be reported another for the engineer to write down the ACTION TAKEN.
3- There is a book called MMEL "Master Minimum Equipment List" in each aircraft. The MMEL is issued by the manufacturer and approved by the Civil Authorities like FAA, EASA, CAA, ...etc. Note that any airline can make more restrictions to what is mentioned in the MMEL but can't reduce what is already in it. In this case the MMEL will become MEL - Minimum Equipment List-.
4- The MMEL or MEL is the book that has most of the faults mentioned in. It will give the minimum requirment needed for the fault to be dispatched. Like it will mention if this fault is "GO", "NO GO", or "GO IF...". In the MEL also there will be for some faults the code "M" or "O" and or BOTH. The "O" is stated for OPERATIONAL PROCEDURE while the "M" is stated for MAINTENANCE PROCEDURE. That means if this fault occurs then the Pilots have specific procedure to carry out during aircraft operation regarding that system or flight and in "M" case that means the maintenance has procedure to do before dispatching the aircraft. Please note that MEL items are categorized in dispatchable time limitation such as maybe some faults are GO item for maximum limited number of flights another are dispatcheable for maximum number of days and some them are dispatcheable in some atmospheric conditions.
5- The captain can REJECT what the engineer is saying if he felt not convinced in such dispatchable conditions mentioned in the MEL because in some cases he believe in this atmospheric climate condition he may face the next flight as he can see in the meteorology report some troubles. Anyway he can REJECT the action taken and usually in this case this issue will be reported to the MANAGEMENT so they will advice the flight crew what to do or advice the Maintenance personal of what to do. LAST DECISION WILL BE FOR THE PILOTS as they are going to fly this aircraft.
6- there are some faults that you will not find in the MEL. like LEAK. We can find the dispatchable limitation for any leak in the AMM - Aircraft Maintenance Manual - that will state the dispatchable leak limitation and according also to the leak limitation.
7- Some findings maybe like structore damage, in this case the reference will be something called SRM "Structural Repair Manual" that will give the dispatchable measurements of that damage and always we put into consideration if this damage location in pressurized or unpressurized zones on the aircraft.
So far, I hope that this briefing clarify the way of dispatching any aircraft for the next flight. At the end of each aircraft log book page, the ground engineer, or technician, or mechanic will sign certification that the aircraft is safe for the next flight and then the CAPTAIN will sign final acceptance for that aircraft to take.
Best Regards
Ayman Shak'ah
Licensed Aircraft Maint. Engineer
Subscribe to:
Posts (Atom)
