WINTER INTERNSHIP REPORT 2015-16

NAME:WAREESHA HASAN

UNIVERSITY: NED UNIVERSITY OF ENGINEERING AND TECHNOLOGY- KARACHI

FIELD: METALLURGICAL ENGINEERING

ROLL NO: MY-053 (BATCH: 2013-2014)

CONTENTS1. INTROTUCTION1.1 AIRCRAFT’S ON BOARD DOCUMENTS1.2 MOVEMENTS OF AIRCRAFT2 VISIT AT WORKSHOPS,TESTING AND QUALITY CONTROL

LABS2.1 NON-DESTRUCTIVE TESTING(NDT) SECTION2.1.1 METHODS OF NDT2.1.2 METHODS OF NDT2.2 THERMAL SPRAY WORKSHOP2.2.1 PLASMA SPRAY 2.2.2 WIRE ARC SPRAY2.3 QUALITY CONTROL LAB2.4 HEAT TREATMENT AND WELDING WORKSHOP2.4.1 TUNGSTEN INERT GAS/ARGON WELDING2.4.2 WELDING TEST2.4.3 HEAT TREATMENT FURNACE 2.5 ELECTROPLATING SECTION

1. INTRODUCTION

Pakistan International Airlines commonly known PIA is first founded in 1947 as Orient Airways then on 10 January 1955 as Pakistan International Airlines Corporation – PIAC. It operates scheduled services to 23 domestic destinations and 30 international destinations in 27 countries across Asia, Europe and North America. Its main hubs are Karachi, Lahore and Islamabad/Rawalpindi. Secondary hubs include Peshawar, Faisalabad, Quetta, Sialkot and Multan.

Pakistan International Airlines (PIA) fleet include the following Aircraft :

Airbus A310-300, Airbus A320-200

ATR 42-500 , ATR 72-500

Boeing 777-200ER , BOIENG 777-200LR, BOEING 777-300ER

1.1 AIRCRAFT ‘S ON BOARD DOCUMENTS:

CERTIFICATE OF REGISTRATION CERTIFICATE OF AIRWORTHINESS AIR OPERATOR CERTIFICATE CERTIFICATE OF MAINTAINANCE DIS-INSECTION CERTIFICATE FUEL CERTIFICATE CERTIFICATE OF REGISTRATION FROM CIVIL AVIATION AUTHORITY (CAA)

1.2 MOVEMENTS OF AIRCRAFTS:

There are three types of movements of aircrafts.

Pitching Yawing Rolling

AILERONS:To turn the airplane, the pilot uses the ailerons to tilt the wings in the desired direction.

RUDDER:A pilot usually uses the rudder along with the ailerons to turn the airplane.

ELEVATOR:On the horizontal tail surface,Elevators are present which tilt the nose of the airplane up and down.

2. VISIT AT WORKSHOPS ,TESTING AND QUALITY CONTROL LABS

During the internship period I visited different workshops and inspection labs .The details of these visits are given below:

2.2 NON-DESTRUCTIVE TESTING SECTION:

2.1.1 NON-DESTRUCTIVE TESTING:

The use of noninvasive techniques to determine the integrity of a material, component or structure or quantitatively measure some characteristic of an object.i.e. Inspect or measure without doing harm.

2.1.2 Methods of NDT

The methods of Non-Destructive Testing that are being used for cracks detection in Pakistan International Air Line are as follows :

1.Eddy-Current Testing (ECT)

2.Magnetic Particle Inspection (MT/MPI)

It has two units:

Manetizing unit De-Magnetising unit

3.Radiography

4.Fluorescent Penetrant Inspection

5.Ultrasonic

EDDY CURRENT TESTING:

Eddy-current testing (also commonly seen as eddy current testing and ECT) is one of many electromagnetic testing methods used in nondestructive testing (NDT) making use of Electromagnetic induction to detect and characterize surface and sub-surface flaws inconductivematerials.It consist of masking tape.HFEC(High frequency eddy current ) is used for Surface crack detection.LFEC(Low frequency eddy current) is used for Sub-Surface crack detection.ECT has a very wide range of applications. Because ECT is electrical in nature, it is limited to conductive material. There are also physical limits to generating eddy currents and depth of penetration (skin depth).

Magnetic Particle Inspection (MT/MPI):

The part is magnetized. Finely milled iron particles coated with a dye pigment are then applied to the specimen. These particles are attracted to magnetic flux leakage fields and will cluster to form an indication directly over the discontinuity. This indication can be visually detected under proper lighting conditions.

Radiography:

The radiation used in radiography testing is a higher energy (shorter wavelength) version of the electromagnetic waves that we see as visible light. The radiation can come from an X-ray generator or a radioactive source. Radiographic testing (RT)offers a number of advantages over other NDTmethods, however,one of its major

disadvantages is the health risk associated with the radiation.

Fluorescent Penetrant Inspection:

Fluorescent penetrant inspection (FPI) is a type of dye penetrant inspection in which a fluorescent dye is applied to the surface of a non-porous material in order to detect defects that may compromise the integrity or quality of the part in question. Its a low cost and simple process.

ULTRASONIC TESTING(UT):

Utrasonic testing (UT) is a family of non-destructive testing techniques based on the propagation of ultrasonic waves in the object or material tested.This testing has High penetrating power, which allows the detection of flaws deep in the part.It hasHigh sensitivity, permitting the detection of extremely small flaws.Its aNon hazardous testing technique and has no effect on equipment and materials in the vicinity. Capable of portable or highly automated operation. Results are immediate and on the spot decisions can be made.

2.2 THERMAL SPRAY WORKSHOP

In this workshop two types of Thermal spraying processes for aircraft and engine repairing were explained, which are as follows:

1.PlasmaSpraying Process

2.Wire Arc Spraying Process

Surface preparation is the essential first stage treatment of a substrate before the application of any coating therefore the specimen to sprayed or coated is first cleaned.This cleaning involved the following steps:

Cleaning:It required solvent de-greasing.

Masking:The masking tape

Grit Blasting:Heavy dust and etching is removed by Grid blasting.

After these steps starts the spraying process,either plasma spraying or wire arc spraying.

2.2.1 PLASMA SPRAYING PROCESS:

The plasma spraying process involves the latent heat of ionized inert gas (Plasma) being used to create the heat source. The most common gas used to create the plasma is argon, this is referred to as the primary gas.Argon flows between the electrode and nozzle. A high frequency or high voltage alternating electric arc is struck between the nozzle and the electrode, which ionizes the gas stream. By increasing the arc current, the arc thickens and increases the degree of ionization. This has the effect of increasing the power and also, due to the expansion of gas, an increase in the velocity of gas stream.With a plasma created by argon only it requires a very large arc current (Typically 800 to 1,000 amps) to create sufficient power to melt most materials. With this level of arc current the velocity may be too high to allow materials with a high melting point to be made molten. Therefore, to increase the power to a level sufficiently enough to melt ceramic materials it is necessary to change the thermal and electrical properties of the gas stream. This is generally done by adding a secondary gas to the plasma gas stream (usually Hydrogen).Once the appropriate gas stream has been established,the molten particles accelerate towards the work piece and forms the coating.Note:Plasma gun temperature ranges from 1500-50,000F.

2.2.2 WIRE ARC SPRAY:

For the electric wire arc spray process, we use two metallic wires, usually of the same composition, as the coating feedstock. The two wires are electrically charged with opposing polarity and are fed into the arc gun at matched, controlled speeds. When we bring the wires together at the contact point, the opposing charges on the wires create enough heat to continuously melt the tips of the wires. We use compressed air to atomize the now molten material and accelerate it onto the workpiece surface to form the coating.

Note:Wire Spray thermo gun temperature ranges from 20,000-35000F.

Major advantages of Wire Arc Spray coating method include lower operating costs, higher material output per hour. Wire Arc coatings are exceptionally suited for dimensional restoration of both mis-machined and worn parts.

2.3 QUALITY CONTROL LAB:

After Plasma/Wire spray the specimen is brought into quality control test lab.This lab consist of following machines:

Tensile Bond Strength Specimen cutting Machine Grinding,Polishing Machine Metallurgical Microscope Rockwell Superficial Hardness Testing Machine Profilometer Roughness Testing

2.4. HEAT TREATMENT AND WELDING WORKSHOP

This workshop consist of heat treatment furnaces and welding work.

2.4.1. TUNGSTEN INERT GAS/ARGON WELDING:

In gas tungsten−arc welding (GTW),formerly known as TIG welding (for tungsten inert gas), the filler metalsupplied from afiller wire(because the tungsten electrode is not consumed in this operation, a constant andstable arc gap is maintained at a constant current level. The metal is similar to the metals to be welded.The power supply is either DC at 200 amps. Or AC at500 ampere.Depending on the metal to be welded. In general, AC is preferred for aluminum and magnesiumbecause the cleaning action of AC removes and improves weld quality.

Note:For the welding on Al and Mg the AC supply is provided and for the Stainless steel,Ti,Ni DC supply is provided.

Shielding gasas are also used in this TIG Welding in order to prevent contamination of weld and prevent electrode deterioration .

2.4.2. WELDING TEST

The welding test involved:

1.Back Bend Test2.Tension Test3.X-Ray

2.4.3. HEAT TREATMENT FURNACE

Heat treatment is a process used for stress relieving or age repairing welds and cold-weld areas.The heat treatment cycles described in this section are identified in groups related to the type of furnace atmosphere required.Cycle code numbers with the prefix letter “V”,”I”,”A” and “H” shows the atmosphere requirements for vacuum ,inert gas, air , and hydrogen respectively.In this section there are three furnaces .Vacuum furnace, Electric Furnace, and Gas Furnace.

VACUUM FURNACE:

Vacuum furnace is a type of furnace that can heat materials, typically metals, to very high temperatures and carry out processes such as brazing, sintering and heat treatment with high consistency and low contamination.This furnace has no air.The inert gas which is used is “Argon Gas” present in argon gas chamber near the furnace.This furnace is run by the transformer .

2.5 ELECTROPLATING SECTION:

We also visited electroplating section at Engine Overhaul Plant.The Purposes of Electroplating are:

1. Appearance2. Protection3. Special surface properties4. Engineering or mechanical properties

The cathode would be the piece to be plated and the anode would be either a sacrificial anode or an inert anode, normally either platinum or carbon (graphite form).The electrons are transferred from the anode to the cathode and is underwent in a solution containing silver.In this diagram the anode is Silver and the other surface which is to be plated is Cathode.

In this electroplating section ,the parts of aircraft and engine which gets damaged due to wear and tear and internal stresses are treated.Five types of plating is done in this section which are as follows:

1.Chromium Plating

2.Copper Plating

3.Silver Plating

4.Nickel Plating

5.Cadmium Plating