PIA internship report

STUDY OF ENGINE OVERHAUL SHOP AT

PIA

GROUP A:

NED UNIVERSITY METALLURGICAL DEPARTMENT (THIRD YEAR 2014)

AZEEM BIN USMAN (MY-069)

SHAHROZ AHMED (MY-056)

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ACKNOWLEDGEMENTS

Since undertaking the task of writing this report, instructors and management, too numerous to mention,

have guided us in the best of their health and have shared their experience and input and contributions on

how to make this work more effective as a learning tool .To all those who have helped by any means, we

express our sincere thanks.

Appreciation is expressed to those who have made our tour easy and provided us assistance, so we can

explore and learn more. We are especially indebted to Mr. Nadeem , who provide us the easiest route of

exploring and advised us the best instructors in the respective section. We are sincerely thankful to Mr.

Najeeb, who granted us permissions to visit respective sections of our interest and helped in every aspect

of our visit. Mr. Ather (in charge of plasma section)for his continual encouragement and support.

In the end, our sincere thanks to all those who have made our journey to PIA successful and free of

worries , their contribution is deeply and sincerely appreciated.

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PREFACE

In this report, we have discussed our learning experience at Pakistan International Airlines(PIA).The

report has main considerations at the engine overhaul and its subdivisions .some of which includes

cleaning, electroplating, plasma spray areas, non-destructive testing sections, pneumatic areas etc.

Being as metallurgical engineers, we have tried to get most of our focus to the latest methods followed in

PIA related to metals and materials which includes protective coating of metals such as anti-corrosive

coatings, thermal barrier coatings, electroplating etc., cutting of parts through CNC machining, crack

detection by best of methods available, heat treatment, welding etc.

Our primary objective was to submit and share the maximum knowledge to the reader about the latest

methods adopted by PIA to give strict attention for the maximum protection of the parts of aircraft, their

usage period, cleaning through proper method, ensuring the parts dimensions from time to time,

maintenance, flaw detection and scrap in a way that it cannot be used for future by any means.

We hope that our work would be successful in accomplishing our goal.

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S.NO. CONTENTS PAGE NO.

01 CNC MACHINE 05

02 EROM AREA 06

03 MACHINE SHOP 06

04 ELECTROPLATING 11

05 THERMAL SPRAY CLASES 14

06 PAINT SHOP 16

07 WELDING 17

08 HEAT TREATMENT 17

09 AERO FILE SECTION

18

10 STRIPPING AND ASSEMBLY SECTION

18

11 CLEANING SHOP 20

12 NON DESTRUCTIVE TESTING 21

13 VIEW ROOM 23

14 PLANNING 23

15 STANDARDS ROOM

24

16 PNEUMATIC SECTION 25

17 TEST BENCH 26

18 QEC BUILDUP 26

19 LANDING GEAR SHOP 27

20 WHEEL BAY 27

21 HYDRAULIC SYSTEM AND REPAIR 28

22 HYDROSTATIC TEST 28

23 EXPERIENCE 29

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ENGINE OVER HALL SECTION

After certain life engine is subjected to over haul section weather it is accessible or not to investigate it

and finish parts to enhance or increase the life of engine and as well as other parts.

STATES OF ENGINE OVERHALL SECTION:

Some states in which the parts of plane get subjected for increasing the life of parts are

1. CNC Machine

2. Erom area

3. Machine shop

4. electroplating

5. Electroplating

6. Thermal spray shop

7. welding

8. Heat treatment

9. Aerofile section

10. Stripping and engine assembly section

11. NDT testing

12. Planning room

13. Standard room

14. Pneumatic

15. Test bench

16. QEC buildup

17. Landing gear

18. Wheel bay

19. Hydraulic system and repair

20. Hydraulic test

1. CNC MACHINE:

CNC stands for “computer numeric control”. In CNC machines data is feed in machine which can

regulate the whole process automatically without need any labour or manual work.

There are several CNC machines which can frequently used in Pakistan international airline

which increases the quality of engine parts.

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2. EROM AREA:

Erom is a largest machine which is found in Erom area. It is vertical multiple operated machine

where lathe machine process take place. It is computer numeric control and a highly automated

machine.

It is a manufacturing and as well as repairing machine use for cutting, chipping and many other

purpose.

3. MACHINE SHOP:

Some machine used in PIA are CNC and as well as manually operated machine.

Lathe machine

CNC lathe machine

Milling machine

Horizontal boring machine

Grinding machine

3.1. LATHE MACHINE:

Lathe machine are considered as the mother of all machines. It can be vary in sizes. For large

parts large lathe machines used such as fixture plates etc. the sizes of lathe machine depend upon

the bed length and height from the center. Higher the distance the larger diameter products can be

produces.

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working mechanism:

The mechanism of lathe machine is similar to metal forming and shaping techniques. In lathe

machine the work piece is dynamic and holds in a die which moves the part and the tool is

stationary. Tools can be change with specified material.

Coolants:

Coolants must be use in machine to remains the work piece cool to prevent the excessive heat

distortions. Domes can be used as coolant.

Application:

Lathe machine is used for drilling and formation of threads in parts, some sort of cuts can also be

produced with lathe machine.

Limitations:

The limitation of lathe machine is that it can only operate with the parts having only circular cross

section. It cannot be used for rectangular or any polygonal parts.

Precautions:

Job should be hold lightly in a die.

Care should be taken properly where scrap can be produced

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Eye shields, hand gloves properly used

3.2. CNC LATHE MACHINE:

CNC lathe machine is vertical lathe machine in which tool is positioned in vertical direction. It is

a manufacturing and as well as repairing machine.

Data is feed in machine then the machine process automatically to make parts. CNC lathe

machine is vertical in position, a chunk which hold work piece can be rotated. For large parts,

having a high weight so it can be made vertical to carry machining operation easily.

Application:

Landing gear, jaws can also be produced with this machine which are highly irregular in shape.

3.3. MILLING MACHINE:

The mechanism of working of milling machine is inverse of lathe machine in which the tool is

moving where as the work piece is stationary and hold tightly in a die.

In milling machine, milling cutters are used. The benefit of using milling machine is that any type

of job in shape can be practice in milling machine.

In milling machine the position of tool is either vertical or horizontal

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3.4. CNC MILLING MACHINE:

In CNC milling machine tool is place vertically. The main advantage of CNC milling machine is

that drawing can be made by using different softwares such as autocat and feed in a machine

which can work automatically by single command without need of labour.

Use of milling machine:

Perforated parts holes in parts can be produced by milling machine.

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3.5. HORIZONTAL BORING MACHINE:

This machine is considered to be as one of the largest machine in PIA. It is a CNC machine.

Horizontal boring machine is comprises of both lathe and as well as milling machine where both

machine’s process can be performed in a single machine.

This machine has multiple axis of rotation. Machine which is present in PIA five axis of rotation.

It can rotate longitudinally transverse, rotational about its axis and left right and up and down.

These movements can be take place after a specified time which is mentioned in manual provided

by the manufactures

Bushes can be used in this machine which prevent the tearing wearing of parts and degrade by

itself.

This machine is horizontal in position and data is feed in codes such as G and M codes are used G

stand for geometric and M stands for machining.

3.6. GRINDING MACHINE:

Grinding machine is commonly used for surface parts. Hard materials such as tungsten carbide is

very difficult tube machined so in place of machining operation grinding of surfaces is carried

out.

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Parts before service are plated in order to prevent from oxidation rusting, scaling when these

coating degrades, so obsolete skins of coating (e.g.: chromium plating) can be removed by

grinding upto optimum thickness with high accuracy.

4. ELECTROPLATING:

Plating means coating of some other material in engine parts.

Plating can be carried out either by providing current is a solution known current is a solution

known as electroplating or either without providing electricity.

After the repairing of part work piece it is subjected to difficult sections according to the

requirements. Parts are inspected which are required to be coated and then transfer to plating

section.

Electroplating shop

4.1. COATING METALS:

There are several metals used in PIA for coating purpose these are

Copper plating

Nickel plating

Chromium plating

Cadmium plating

Silver plating

4.2. PRINCIPLE OF ELECTROPLATING:

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The electroplating process is based on a principle in which the ions present in a solutions moving

towards their respective electrodes.

Parts which going to be plated is hang vertical with wire and dipped in a tank.

Current is passing in work piece part either connected with negative terminal known as cathode

or with as positive one known as anode.

Ions in solution move towards their respective electrode and deposition on part, which can

resulting a coating of metal on work piece. Part remains in a solution until a required thickness is

achieved.

4.3. MASKING / WAXING:

This step is carried out before the plating. In this step the regions where plating is not required are

left and rest of the regions covered with masking sticky sheet. The part is then dipped in wax tub

where the wax coated in exposed areas. Making can be removed so that wax remains only a

region where metal coating is not required after plating process the war is then removed.

4.4. PURPOSE OF PLATING:

Plating of some other material on engine parts is carried out to prevent the part from corrosion,

scales formation, wearing and tearing, and to increase the life of parts.

4.5. LABORTARY TESTING:

Solution in tanks for plating purpose are first compose in labs according to the manual provided

by manufacturers.

Solution is tested after a certain period of time in order to retain the proper composition and

elemens are added.

Solution testing is carried out by means of titration process to check the acidity and basicity of

solution.

Tukore (centrifugal rotater) is used to check the amount of sulphate in solution.

4.6. TYPES OF PLATING:

4.6.1. ALCHROME PLATING:

In alchrome plating process the solution contains aluminum and chromium ions. In this technique

there is no need to supply current. Initially parts dipped in hot water to remove paints, coatings,

grease etc .then dipped in alchrome tank, and there is no need of thick layer.

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4.6.2. CHROME PLATING:

To make the parts more resistive to corrosion and rust chrome plating is usually done.

Parts to be plate is hanged on a tank, since the chromium is positively charged ion so it attracts

towards the cathode and deposited on parts. Tank usually use for chromium plating filled with

several balls. In order to prevent the toxic fumes in atmosphere. One of the hazards of chromium

plating is that chrome is positively charge ion and hydrogen from water is also a positively charge

so hydrogen also entrapped it cathode this will result in generation of cracks at high pressure

avoid. This type of failure must be backed for several times to remove the entrapped hydrogen.

4.6.3. COPPER PLATING:

The procedure is similar to all other types of plating. Copper plating is a protective coating. The

solution in a tank containing copper ion which deposition on part with the passage of electric

current.

4.6.4. CADMIUM PLATING:

Cadmium coating is also a protective coating. Since the solution contains cadmium and as well as

hydrogen ions which are deposition on cathode so parts must be baked later. There are two types

of cadmium plating.

Low hydrogen plating:

Low hydrogen plating done on high strength parts made up of steel, iron, alloys because these

parts subjected to high forces so hydrogen is necessary to remove.

High hydrogen plating:

High hydrogen plating for low strength parts which are not subjected to high forced.

4.6.5. NICKLE PLATING:

Nickel plating is a protective coating. Nickel plating is primary plating. For highly damaged

parts initially it is nickel plated and then chromium plated for protective purpose.

4.7. DEPLATING TECHNIQUE:

After a certain life time different parts of plane are disassemble and transfer to engine over

haul in order to repair parts and increase its life.

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The initial step is to clean the plate from any type of coating. Electroplating is usually

removed by reversing the current in parts so the ions deposited part leave the part and remain

in solution.

Other methods are by dipping the part in different chemical solution.

4.8. SKIN ROUGHNESS TECHNIQUE:

Rough surface are generated in some parts to increase the resistance and then it is

electroplated. Some methods to increase roughness are as follows.

DRY BLAST:

In dry blast technique the metallic powder in microns is blasted through gun on parts with

tremendous amount of velocity.

This phenomenon is also used for relieving the residual stresses on parts known as short

pinning.

REVERSING CURRENT:

By reserving the current on part plating is removed which resulting the rougher surface.

ETCHING:

Rough surface can be generate by etching the part is dipped in acid which resulting the rough

surface.

5. THERMAL SPRAY CLASES:

There are three classes of thermal spray these are.

Plasma spray

Thermo spray

Metal spray

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5.1. PLASMA SPRAY:

Plasma is considered to be as a fourth state of matter having a highly oxidized ions and it is a

state lies between the gases and liquids.

Why some materials are plasma coated?

Some parts of engine are highly expensive and high cost effective so the degradation of such

parts must be prevented in order to increase the life of parts. This can be achieved by coated

the part with plasma.

Mechanism:

Plasma spray is just only a method to produce heat.

Heat is required to heat the powder or red hot the powder and soften it rather liquefy.

5.2. PLASMA TESTING LABORTORY:

To check the quality of work piece after plasma coating several equipment used.

5.2.1. TENSILE BOND STRENGTH:

Equipment is similar to the tensile strength equipment. In this test the part is joint with the

bonding agent such as some thermo resin (epoxy). Now this test piece is subjected under tensile

load and due to stress concentration part can be broken at the bonded region, so this equipment

helps us to determine the tensile bond strength of a material.

5.2.2. CUTTING MACHINE:

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After the plasma spray part is then cut by using the cutting machine. Work piece must be hold

tightly at same side of blades in between jaws. The coolant is used to cool the blade and work

piece during cutting. Now this work piece is mounted to check the quality control of work piece.

5.2.3. POLISHING:

The mounted part is being polished by using different emly papers in order to get a finished and

polished surface.

5.2.4. ROCKWELL SUPERFICIAL (HARDNESS TESTER):

Rockwell superficial is used to check the hardness of thin parts. Brale indenter or sometimes ball

indenter may be used to check the hardness. Scale N and T is used for ferrous material and W, X,

Y scale is used for non ferrous material.

Initially minor load is applied and to set the dial at zero now applied major load. Hardness

reading can be read from the scale.

For heat generation first plasma is generating by involving two gases.

5.3. THERMO SPRAY :

Thermal spray is similar type of coating as plasma coating only differ in the heat generation

technique.

Heat can be generated by burning the gases at very high temperature at about 18000 to 20000 °C.

In thermo spray wire and powder both can feed in gun.

6. PAINT SHOP:

Paint shop in PIA s considered to be as a part of repair process where the parts after cracks

detection and further processes subjected to paint shop to make the finish product.

Initially the part is being cleaned and by means of chemical, mechanical, and electro refining

process. Now the clean product if required it is masking to prevent the application of the paint in

unwanted regions.

Paint is applied in two steps firstly primer is applied to prevent the part from being corrosion and

degradation it is somehow absorb in a part to provide better coating then in final step enamel is

applied it is finish coat applied for the finishing purpose.

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7. WELDING:

Welding is a joining process. It is a process in which two parts of metal weather similar or

dissimilar atoms join together by generating high amount of heat in between the two parts.

Welding is also considered to be as a repair process in which the broken parts of aircraft being

welded. There are several type of welded conducted to join the parts such as Argon welding,

electric welding, gas welding.

Argon and electric welding welded only similar type of metals.

Gas welding is used to weld the dissimilar metals.

8. HEAT TREATMENT:

Heat Treatment is the controlled heating and cooling of metals to alter their physical and

mechanical properties without changing the product shape. Heat treatment is sometimes done

inadvertently due to manufacturing processes that either heat or cool the metal such as welding or

forming. Heats Treatment is often associated with increasing the strength of material, but it can

also be used to alter certain manufacturability objectives such as improve machining, improve

formability, and restore ductility after a cold working operation. Thus it is a very enabling

manufacturing process that can not only help other manufacturing process, but can also improve

product performance by increasing strength or other desirable characteristics.

Vacuum furnace heat treatment furnaces

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9. AERO FILE SECTION:

Aircraft is lifted in the air due to its shape. Aero file is a shape due to which air smoothly flow

and causes the aircraft to be lifted. Wings of aircraft is made in aero file shape in order to

produce thrust , wings are bulgy at upper surface and straight at lower surface which helps the air

flow most faster at lower surface then above which causes the production of thrust.

Moreover in engine parts turbine blades are also made aero file in shape which moves through

the smooth flow of air.

10. STRIPPING AND ASSEMBLY SECTION

The engine and APU of the aircraft is an assembly of many complex parts and these parts needs

to be replaced or requires maintenance after a certain amount of time. Sometimes, the engine

encounters problems before its maintenance period. This is often due to failure of single part or

some parts present in the engine.

For unlocking these parts from the engine or APU, stripping area provides the needful; when the

maintenance or replacement is complete assembling is also done in this area. This area is

basically used for two functions.

stripping or disassembling

assembling the engine parts

10.1. STRIPPING:

Engine parts are disassembled in this section; this requires expert and skillful people having the

complete knowledge of optimum tool selection. When the required parts are stripped, these are

sent to different areas for detection of flaws, maintenance and replacement.

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Aircraft’s APU present in stripping section

10.2. ASSEMBLY AREA:

When the stripped parts are replaced or serviced, the same section is used for assembling these

parts to make a workable engine, but the routes of both stripping and assembling are different.

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11. CLEANING SHOP:

Before the inspection disassembles parts are firstly cleaned. Cleaning process is carried out in

several cleaning steps.

Hand cleaning

Chemical cleaning

Mechanical cleaning

Electrical cleaning

11.1. HAND CLEANING:

It is an initial step it is a hand cleaning process in which different components cleaned by means

of cloth by means of labor. It is cleaned by different oils and chemicals such as MEK, acetone,

and kerosene oil.

11.2. CHEMICAL CLEANING:

Scales, corrosion, rusting all can be cleaned by chemical cleaning. In chemical cleaning part is

dipped in some chemical solution for cleaning.

11.3. MECHANICAL CLEANING:

In this step cleaning is carried out by machining. Dry blast, vapor blast, sweco processes are the

methods for mechanical cleaning. In short by this method Al2O3 powder is pressurized on parts.

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11.4. ELECTRO CLEANING:

In electro cleaning method tank is filled with non ionic water and is connected with ultrasonic

machine which produce swirling effect due to resonance, component is placed in a tank for

specific time and temperature usually turbine blades cleaned by this method. Water daglocked the

holes and increase the life of part. For assurance we use back flesh machine.

12. NON DESTRUCTIVE TESTING:

Non destructive technique is a technique use to determine the cracks, flaws, leap, and inclusions

without damage to impair its future usefulness.

There are several types of non destructive test carried out at aircraft parts at PIA these are,

Radiography testing

Magnetic particle inspection

Fluorescent penetrant

Ultrasonic testing

Eddy current testing

Radiography:

12.1. RADIOGRAPHY TESTING:

It is a technique use to detect the surface, sub surface and as well as internal flaws. In this

technique X-rays or gamma rays generated to detect the flaws. X-rays generated by the

bombardment of electrons on to the metal this will generate a stream of x-rays which penetrate in

a part to detect the cracks and flaws.

12.2. MAGNETIC PARTICLE INSPECTION:

This technique is usually used to detect the surface and sub surface cracks. It is only applicable

for ferromagnetic components. This test does not detect the internal cracks.

First the component is being magnetized by induction principle. Current passing through a coil

which generates magnetic field part is being place as a core in a coil and magnetizes through

induction. Now iron fillings are sprinkle on surface, iron filling forming a pattern around the

crack because of the N and S poles generated at crack tip and leak magnetic field.

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Magnetic particle inspection

12.3. FLUORESCENT PENETRANT:

In this technique only surface flaws can be detected. Component being tested is first dipped in

fluorescent penetrate and the developer is applied to enhance the crack now the part is examined

under a black light so the cracks appear as bright at dark background.

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Detection of Crack through Fluorescent Inspection

12.4. ULTRASONIC TESTING:

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This is a technique use for several years for detection of flaws by hammering the part and detect

by the sound generated.

There are two types of method used in ultrasonic testing these are,

Pulse echo method

Trough transmission method

In pulse echo method two transducer used and in through transmission method only a transducer

used. Piezoelectric transducer is used which convert the electrical signal into sound energy and

the signal display in oscilloscope. If flaws detected so small signal produced.

12.5. EDDY CURRENT TECHNIQUE:

This technique is used to detect the cracks and composition of component this test conducted in

electrical conductive materia .Eddy current is produce by the induced current in part.

13. VIEW ROOM:

View room is just a place where decision is been taken with the help of component history.

Manual provided by manufacturer and the cycles of aircraft. Cycle is a term used in aircraft, cycle

means take off and landing of aircraft is a one cycle. Cycles or life of aircraft engine is provided

but the manufacturer and after the specified life times the aircraft disassemble and send to

different repairing shops. In view room it is decided that which part is first send to in which

section such as plasma shop. NDT testing, CNC machining. Tags are placed along with

component; yellow tag indicates that this part is repaired

14. PLANNING:

There are several function which are conducted in planning room. These are

Spare provisioning

Quantity of material being used

Projects planning

Labour required

All the above factors are conducted in planning room of engine overhaul shop. Problems occur in

aircraft are also considered in planning room. Planning is actually documentation which is

planned by skilled planners.

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15. STANDARDS ROOM

This room is basically associated with the calibration of instruments .which is used to ensure the accuracy

of instruments. From time to time this practice is repeated depending on the instruments.

Various instruments are calibrated in this section .for example

1. Pressure gauges

2. Screw gauges

3. Hardness testers

4. Torque meters

5. Profilometers

6. Verneir calipers

Pressure gauge torque meter

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Hardness tester

PRINCIPLE AND CALLIBRATION OF PRESSURE GUAGE AND TORQUE METER:

For calibrating pressure gauges and torque meters there is a main(on which accuracy of instruments is

checked) the instrument is connected to the main and then force or pressure is applied if the reading on

the main and instrument is same then there is no error, if there is variation in the readings the instrument

has errors.

PRINCIPLE OF CALIBRATION FOR HARDNESS TESTERS, VERNIER CALLIPERS,

PROFILOMETERS AND SCREW GAUGES:

For ensuring the accuracy of these devices standard test blocks are provided with the instruments by the

supplier.

The standard test block have the value of hardness, depth ,length or roughness etc known, by measuring

the respectable parameters of the test block on the respective instruments we can check the accuracy of

the instruments.

16. PNEUMATIC SECTION:

Pneumatic is a term used in engineering means the movement of different components through

air. To make the pneumatic system properly working three basic things are required these are

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pressure, vacuum and air flow. Pneumatic system in an aircraft is required for air conditioning

system and for bleed purposes.

Basic operation:

Pneumatic system in an aircraft is pretty straight forward. The heart of this system is a pressure

and vacuum creating engine driven air pump.

The air pump draws air into the system through a filter. The fasts moving stream of air passes

over the vanes and power the autopilot and de icing system.

17. TEST BENCH:

In test bench shop whole engine is placed on bench for testing purpose. It is tested and compare with

standard engines provided by manufacture. To prevent the metal particles during oil refining all oil

refining process conducted in test bend shop.

18. QEC BUILDUP:

QEC stands for quick engine change. It is a shop where the internally completed engine is

subjected in order to complete the engine externally. Only internally completed engine does not

meet with all the requirements in aircraft external equipments are necessary to run the aircraft

safe and sound. Only engine can just produce thrust which help aircraft to lift up in air but engine

become a power plant in QEC buildup shop. QEC buildup also generates the tendency of engine

for de icing and anti icing purposes.

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Air compresses which resulting in increase in pressure and temperature which heated air and

apply in different chambers with the help of valves to suspend the ice formation. With the help of

QEC buildup shop the pressure inside the aircraft equal to the atmospheric pressure for the safe

and sound journey of passengers. Furthermore in pneumatic system ducts, valves, exhaust system

are built by QEC shop.

19. LANDING GEAR SHOP:

Landing gear in general term considered to be as the legs of aircraft. It helps aircraft to land

smoothly. It size varies from very small to very huge depending on the size of aircraft. For small

aircraft two gears are enough where as in larger ones more than gears are used. Main gear, nose

gear, wings gear are used in large aircrafts.

These gears come in overhaul shop and disassemble then it is transfer to any repairing section

according to the requirement either for heat treatment process or any other. Gear must be made up

of such material so it should be a shock resistance. For shock absorbance nitrogen and hydraulic

oils are used, it consist of two chambers upper and lower chamber. There is a certain life of gears

and after its life it subjected to engine overhaul shop, for example the life of 747 is 24000 cycles

and for 310 it is 15000 cycles or 8 years.

Main gear and nose gear

20. WHEEL BAY:

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For testing of aircraft wheel are subjected to wheel bay shop. Pressure of wheels and other testing of

wheels tested in this shop.

21. HYDRAULIC SYSTEM AND REPAIR:

A hydraulic system uses a fluid under pressure to drive machinery or move mechanical

components.

Virtually all aircraft make use of some hydraulically powered components. In light, general

aviation aircraft, this use might be limited to providing pressure to activate the wheel brakes. In

larger and more complex aero planes, the use of hydraulically powered components is much more

common. Depending upon the aircraft concerned, a single hydraulic system, or two or more

hydraulic systems working together, might be used to power any or all of the following

components:

Wheel Brakes

Nose Wheel Steering

Landing Gear Retraction/Extension

Flaps And Slats

Thrust Reversers

Spoilers/Speed Brakes

Flight Control Surfaces

Cargo Doors/Loading Ramps

Propeller Pitch Control

A hydraulic system subjected to hydraulic repair shop after the completion of its cycles for

repairing purpose.

22. HYDROSTATIC TEST:

A hydrostatic test is performed to determine the integrity and soundness of pressure vessels and

piping joints. A decrease in the applied pressure or leakage through the products or joints or plastic

deformation or distortion or bulging in the product is indication of inadequate quality of the product

under test. This test method is also termed as Leak testing (based on

the principles of leakage during pressurized condition) and Pressure

Drop Test (based on the principles of decrease in pressure during test

due to unacceptable discontinuities). It is also the most common

method often employed and it is the one of the most reliable test

methods when determining the integrity and soundness of the vessel

This test is preferred over pneumatic test due to safety reasons .This

test is applied on new parts and also on repairs.

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OUR EXPERIENCE AT PIA

At the start of our internship at PIA, we had made our minds to seek maximum knowledge to our

respective engineering field, but PIA not only provided us with maximum knowledge to our respective

engineering field also provided us with the awareness of different engineering aspects followed in PIA.

The kind of difficult situation PIA is facing right now, because of different political issues, we had in

mind that there is less to learn and explore, but credit and sincere thanks to the management that they tried

to help us in every aspect and gave us the maximum knowledge they had, and not only they provided the

theoretical aspect but also gave help practically.

Being as metallurgical engineers, the technologies that attracted most of our attention were,

electroplating, plasma, thermal spray, hardness testers, profilometers, NDT, cleaning, heat treatment,

welding, vacuum furnace etc. we would like to share our detailed experience in:

NDT: As NDT has a great importance in the metallurgical engineer’s knowledge, at PIA we performed it

practically which give us maximum idea of NDT, before the internship we just knew it theoretically.

VACUUM FURNACE: As we all know that it is a rare furnace, we are deeply thankful to the staff

responsible for this furnace that they provided us with maximum information regarding this furnace.

PLASMA AND THEMAL SPRAY COATING: Before coming to PIA we were not aware that such

coating also exists, now we have gained good amount of knowledge about these types of coatings.;

ELECTROPLATING: PIA has provided us with practical explanation of electroplating, before this we

had knowledge about it theoretically, now we know the proper steps followed in electroplating.

CNC MACHINING: We are really thankful to the people of PIA that they gave us a chance to see the

CNC boring machine, lathe machine and milling machine. We were really surprised to see the huge

amount of modern machinery specially that milling machine that works on AUTOCAD .

CONCLUDING REMARKS:

We really like to give our sincere thanks to all the people associated with our internship, to all who

have provided us with accessories and helped us in meeting our needs .We tried to remain disciplined in

this internship period, but if have committed something wrong that affects the management or any person

associated with PIA we would be sorry to the respective person.