UNIVERSITY OF MORATUWA Industrial Training Report

UNIVERSITY OF MORATUWA
Faculty of Engineering
Registered Module No: ME 3992
INDUSTRIAL TRAINING REPORT
Aircraft Engineering Wing
Sri Lankan Airlines (Ltd)
From 02/07/2018 to 14/12/2018
Date of Submission: 07th
of January 2019
Dilshan K.M.G.L.
150131A Department of Mechanical Engineering

i
Preface
This industrial training report presents the engineering training experience gathered by
myself during the industrial training at Aircraft Engineering Wing (AEW) of Sri Lanka Air
Force Base, Katunayake as a Trainee Aeronautical Engineer and Engineering Section of
SriLankan Airlines (Ltd), Katunayake as on the Job Trainee.
The aim of this training was to get experience of the fields of aeronautical engineering
and aircraft maintenance engineering after the completion of two and half years of academic
studies as a student of Mechanical Engineering, Faculty of Engineering at University of
Moratuwa. This report has been prepared as a part of completion of the industrial training
according to the regulations of National Apprentice & Industrial Training Authority (NAITA).
Throughout the 10 weeks from 02nd
July 2018 to 07th
September 2018 in the AEW and
14 weeks from 10th
September 2018 to 14th
December 2018 in the SriLankan Airlines (SLA),
I got the opportunity to learn new things and hands on experience while applying the
knowledge I have gained throughout the 5 semesters. The document mainly consists of three
chapters as the introduction about the training establishment, my overall training experience
and the conclusion on the training.
First chapter of the report consists of an introduction on Aircraft Engineering Wing
(AEW), Sri Lanka Air force and Engineering Section of the SriLankan Airlines with their main
functions, organizational structure, hierarchy level, the current performance of the training
establishment, strengths, weaknesses and opportunities for improvement. I also describe about
the profitability, threats for its survival and its importance to the country along with the
suggestions to improve performance.
Second chapter of the report is about my training experience as a Trainee Aeronautical
Engineer at AEW and On the Job Trainee at SriLankan Airlines in both technical and non-
technical aspects. It also consists of the details of the project, the problems encountered during
while engaging in the tasks, how I overcome those problems and how I faced challenges during
my internship period.
Third chapter gives a summarize on the overall training experience I had during the 104
weeks of internship period. This chapter also contains both positive and negative factors of my
training experience on training establishments’ perspective in order to improve the existing
training process and the improvements that needed to overcome my weaknesses I saw during
the internship period.

ii
Acknowledgement
I would like to express my gratitude and appreciation to the people who supports me in
completing the 10 weeks of internship period at Aircraft Engineering Wing of Sri Lanka Air
Force Base, Katunayake and 14 weeks of internship period at Engineering Section of
SriLankan Airlines, successfully and sharpening my career in an effective way.
First, I would like to pay my sincere gratitude as an undergraduate of Mechanical
Engineering of University of Moratuwa for Prof. Ruwan Gopura (Head of the Department of
Mechanical Engineering), Dr. Nirosh Jayaweera (Aeronautical Stream Coordinator, Senior
Lecturer), Dr. J.G.A.S. Jayasekara (Senior Lecturer) and Dr. R.A.C.P. Ranasinghe (Industrial
Training Coordinator of Mechanical Engineering Department, Senior Lecturer) to their
enormous commitment to provide the final year industrial training at AEW and SLA.
I would like to thank the Industrial Training Division of University of Moratuwa, Eng.
N.A. Wijeyewickrema (Director - Industrial Training Division), Eng. Roy Sankaranarayana
(Senior Lecturer) and the National Apprentice and Industrial Training Authority (NAITA) for
organizing this industrial training programme in a well-structured way.
I would like to express my gratitude to Air Marshal K.V.B. Jayampathy (Commander
of the Sri Lanka Air Force), Air Commodore Prasanna Samarasinghe (Former Commanding
Officer, AEW), Air Commodore S.K.A. Senarathne (Commanding Officer, AEW), Wg Cdr
R.M.K.T.K. Gunasekara (O I/C TP & CS, O I/C Training, OC AR & SS), Sqn Ldr C.D.
Karunarathne (OC Admin, OC Special Project), Sqn Ldr C.C.T. Gamage (OC Propulsion Bay,
OC Wheels & Brakes), Sqn Ldr E.P.D.R. Edirisinghe (OC Electrical Bay, OC Instrument Bay)
and Flt Lt W.A.C.S. Wijesinghe (QAO, OC Component Bay) who are Commissioned Officers
in the AEW for making necessary arrangements to conduct the industrial training in AEW a
success way.
My gratitude goes to Mr. Saman Gunawardena (Quality Assurance Manager of SLA),
Mr. Lasantha Liyanage (Manager Human Resource Operation & Administration of SLA), Ms.
Pavithra Amarasinghe (Talent Resourcing Executive of SLA) for making necessary
arrangements in SLA.
I thank to WO (Hanger Warrant Officer), F/Sgt Kodikara K (Senior Aircraft
Technician, TP), F/Sgt Weerasinghe R.N. (Senior Aircraft Technician, AR & SS), F/Sgt Upul

iii
G.N.G. (Senior Aircraft Technician, AR & SS), F/Sgt Sanath L.W.N. (Senior Aircraft
Technician, NDT), F/Sgt Hapuarachchi H.D.D.N. (Senior Aircraft Technician, NDT), F/Sgt
Peiris D.L.E.H.P. (Senior Aircraft Technician, Engine Bay), F/Sgt Buddadasa S.D.N.C.
(Senior Aircraft Technician, Safety Bay), F/Sgt Perera C.A.S. (Senior Aircraft Technician,
Electrical Bay), F/Sgt Jayasundara J.M.J.B. (Senior Aircraft Technician, Special Projects) who
are Warrant Officers, Non Commissioned Officers and other Junior Non-Commissioned
Officers whose names were not mentioned here, who took generous effort to instruct and
practice the equipment and tools in the aircraft engineering field in AEW.
I thank to Mr. S.T. Bulathsinghala (Aircraft Maintenance Engineer - LIV, Accessories
Workshop), Mr. Kosala Balasooriya (Aircraft Maintenance Engineer - LIII, NDT), Miss
Shenali Thisera (Aircraft Maintenance Engineer - LIII, Avionics Workshop), Mr. R.D.
Weerasekara (Senior Aircraft Maintenance Executive, Base Maintenance), Mr. K. Somarathne
(Senior Aircraft Maintenance Executive, Composite / Paint Shop), Mr. Chandimal Perera
(Aircraft Maintenance Executive, Base Maintenance) who conduct sessions about the tools and
equipment handling in the SLA.
Also, I would like to thank all the Aircraft Maintenance Engineers, Aircraft
Maintenance Approve holders, Aircraft Maintenance Technicians and Multitask peoples whose
names were not mentioned above and helped me to complete the training.
Finally, I would like to thank all the interns from University of Moratuwa for the
cooperation and the support given to me during my internship period.

iv
Table of Content
Preface.........................................................................................................................................i
Acknowledgement .....................................................................................................................ii
Table of Content .......................................................................................................................iv
List of Figures........................................................................................................................ viii
List of Tables ............................................................................................................................ix
Abbreviations.............................................................................................................................x
Chapter 1 – Introduction of Training Organization ...................................................................1
1.1 Aircraft Engineering Wing ..............................................................................................1
1.1.1 History and Introduction about the AEW .................................................................1
1.1.2 Organizational Structure ...........................................................................................2
1.1.3 Nature of the Business and capabilities of Aircraft Engineering Wing....................2
1.1.4 Different Bays and Sections......................................................................................3
1.1.5 SWOT Analysis ........................................................................................................4
1.1.5.1 Strengths ............................................................................................................4
1.1.5.2 Weaknesses........................................................................................................4
1.1.5.3 Opportunities......................................................................................................4
1.1.5.4 Threats................................................................................................................4
1.2 Engineering Section, SriLankan Airlines (Ltd) ...............................................................5
1.2.1 Introduction about SriLankan Airlines (Ltd) ............................................................5
1.2.2 Brief History about the Sri Lankan Airlines.............................................................5
1.2.3 Organizational Structure ...........................................................................................6
1.2.4 Nature of Business and Capabilities .........................................................................6
1.2.5 SWOT Analysis ........................................................................................................8
1.2.5.1 Strength..............................................................................................................8
1.2.5.2 Weaknesses........................................................................................................8
1.2.5.3 Opportunities......................................................................................................8
1.2.5.4 Threats................................................................................................................8
Chapter 2 – Training Experience ...............................................................................................9
2.1 Aircraft Engineering Wing ..............................................................................................9
2.1.1 Aircraft Repair and Salvage Section (AR & SS)......................................................9
2.1.1.1 Machines, Tools and Equipment........................................................................9
2.1.1.2 Aircraft Materials.............................................................................................10

v
2.1.1.3 Types of Rivets and Fasteners .........................................................................10
2.1.1.4 Hands on Experience .......................................................................................10
2.1.2 Composite Bay........................................................................................................11
2.1.2.1 Types of materials............................................................................................11
2.1.2.2 Vacuum Bagging procedures...........................................................................11
2.1.3 Non-Destructive Testing Lab..................................................................................12
2.1.3.1 Visual Inspection .............................................................................................13
2.1.3.2 Liquid Penetration Inspection (LPI) ................................................................13
2.1.3.3 Magnetic Particle Inspection (MPI).................................................................14
2.1.3.3.1 Magnetizing Bench Method...................................................................................14
2.1.3.3.2 AC/DC Yoke..........................................................................................................14
2.1.3.4 Eddy Current Inspection ..................................................................................15
2.1.3.5 Ultrasonic Inspection .......................................................................................16
2.1.3.6 X-Ray Test.......................................................................................................16
2.1.4 Engine and Propulsion System Bay........................................................................17
2.1.4.1 Kfir Test Cell ...................................................................................................17
2.1.4.2 Dynamically balancing of Compressor turbine ...............................................17
2.1.4.3 Videoscope and Borescope..............................................................................18
2.1.4.4 Turbine blade riveting and de-riveting ............................................................18
2.1.4.5 Spectrometric Oil Analysis Program (SOAP) .................................................18
2.1.5.6 Design a puller .................................................................................................19
2.1.5 Safety Equipment Bay ............................................................................................19
2.1.5.1 Parachutes ........................................................................................................19
2.1.5.2 Survival Packs..................................................................................................20
2.1.5.3 Fire Bottles.......................................................................................................20
2.1.5.4 Anti-G-Suit ......................................................................................................21
2.1.5.5 Life jackets and Life rafts ................................................................................21
2.1.6 Electrical Bay..........................................................................................................21
2.1.6.1 Ground Power Unit (GPU) ..............................................................................21
2.1.6.2 Starter Motor....................................................................................................22
2.1.6.3 Battery Charging..............................................................................................22
2.1.7 Instrument Bay........................................................................................................23
2.1.7.1 Micro Manometer ............................................................................................23
2.1.7.2 Altimeter ..........................................................................................................23
2.1.7.3 Air Speed Indicator (ASI)................................................................................23

vi
2.1.7.4 Vertical Speed Indicator (VSI) ........................................................................24
2.1.7.5 Artificial Horizon (AH) ...................................................................................24
2.1.7.6 Aircraft Weight and Balancing ........................................................................24
2.1.8 Special Projects Section..........................................................................................25
2.1.8.1 Aircraft Systems...............................................................................................25
2.1.8.2 Oil System........................................................................................................26
2.1.8.3 Fuel System......................................................................................................26
2.1.8.4 Helicopter Inspection.......................................................................................27
2.1.8.5 Aircraft preparation for inspection...................................................................27
2.1.8.6 Helicopter Rotor Blade Removal.....................................................................28
2.1.8.7 Aircraft Log Book............................................................................................28
2.1.8.8 Helicopter maintenance documents .................................................................29
2.1 SriLankan Airlines Engineering Section .......................................................................30
2.2.1. Technical Services .................................................................................................30
2.2.2 Avionics Workshop ................................................................................................31
2.2.2.1 Battery Workshop............................................................................................31
2.2.2.2 Electrical Workshop.........................................................................................32
2.2.2.3 Fuel & Waste Workshop..................................................................................32
2.2.2.4 Galley Workshop .............................................................................................33
2.2.2.5 Oxygen Workshop ...........................................................................................33
2.2.2.6 Radio/ IFE Workshop ......................................................................................34
2.2.3 Composite/Paint Shop.............................................................................................35
2.2.3.1 Materials in the Composite section..................................................................35
2.2.3.2 Vacuum bagging process .................................................................................36
2.2.4 Wheels/Brakes Shop...............................................................................................37
2.2.4.1 Main Landing Gear Disassembly, and Assembly Process – A330..................37
2.2.4.2 Main landing gear Carbon Brake Assembly and Testing – A321 ...................38
2.2.5 Accessories Workshop............................................................................................39
2.2.6 NDT Workshop.......................................................................................................39
2.2.6.1 Visual Inspection .............................................................................................39
2.2.6.2 Liquid Penetration Inspection..........................................................................39
2.2.6.3 Magnetic Particle Inspection............................................................................40
2.2.6.4 Eddy Current Inspection ..................................................................................40
2.2.6.5 Ultrasonic Inspection .......................................................................................41
2.2.6.5.1 Ultrasonic phase array fan blade inspection...........................................................41

vii
2.2.6.6 X-Ray Test.......................................................................................................43
2.2.6.7 Elasticity of Laminate Checker – ELCH .........................................................43
2.2.6.8 Thermography..................................................................................................44
2.2.7 Structures Shop.......................................................................................................45
2.2.7.1 Hi-Lok installation...........................................................................................45
2.2.8 Engine Module Shop...............................................................................................46
2.2.8.1 Types of aircraft engines..................................................................................46
2.2.8.2 Fan blade Installation.......................................................................................46
2.2.9 Base Maintenance ...................................................................................................47
2.2.9.1 Different checks of the aircraft ........................................................................47
2.2.9.2 Landing gear hydraulic systems.......................................................................47
2.2.9.3 Cockpit observation .........................................................................................47
2.2.9.4 Engine ground run............................................................................................48
Chapter 3 - Conclusion ............................................................................................................48
3.1 Training Experience.......................................................................................................48
3.2 Weaknesses Identified ...................................................................................................48
3.3 Evaluation on Training Establishment...........................................................................49
Annex 1 – Design a puller to remove outer cover of PT6-3T type engines. ...........................xii
Introduction..........................................................................................................................xii
Observe the outer cover and get measurements...................................................................xii
Production Drawings ..........................................................................................................xiv
References............................................................................................................................ xviii

viii
List of Figures
Figure 1.1 Aircraft Engineering Wing Crest..............................................................................1
Figure 1.2 Organizational Structure of Aircraft Engineering Wing ..........................................2
Figure 1.3 SriLankan Airlines Engineering Logo......................................................................5
Figure 1.4 Organizational Chart of Engineering Section, SLA.................................................6
Figure 2.1 Typical Components of a Vacuum Bagging System..............................................12
Figure 2.2 Magnetizing Bench.................................................................................................14
Figure 2.3 Inspect using AC/DC Yoke....................................................................................15
Figure 2.4 PHASE 2D Eddy Current Test Machine................................................................15
Figure 2.5 ERESCO MF4 Portable Industrial X-ray Generator..............................................16
Figure 2.6 General Mechanism of the GPU.............................................................................22
Figure 2.7 Micro Manometer...................................................................................................23
Figure 2.8 Jacking by load cells...............................................................................................24
Figure 2.9 Swash Plate Mechanism.........................................................................................28
Figure 2.10 Battery Short Circuit Diagram..............................................................................32
Figure 2.11 Coffee Maker Tester.............................................................................................33
Figure 2.12 Booster Pump .......................................................................................................34
Figure 2.13 Layers of Materials Used......................................................................................36
Figure 2.14 Vacuum Bagging..................................................................................................37
Figure 2.15 FORSTER - DEFECTOMETER H used in eddy current test..............................40
Figure 2.16 Ultrasonic Fan Blade Inspection Kit ....................................................................41
Figure 2.17 ANDREX X-ray machine.....................................................................................42
Figure 2.18 ELCH equipment..................................................................................................43
Figure 2.19 Thermography camera..........................................................................................43
Figure 2.20 Jig Lift ..................................................................................................................43
Figure 2.21 Hi-Lok ..................................................................................................................44
Figure 2.22 IAE V2500 Engine ...............................................................................................45
Figure 2.23 Ground run of 4R-ALS.........................................................................................46

ix
List of Tables
Table 2.1 Tools and Machines used in AR & SS ......................................................................9
Table 2.2 Emergency parachute types in the SLAF ................................................................19
Table 2.3 Materials used in Composite Section.......................................................................35
Table 2.4 Flight hour maintenance interval of A320...............................................................47

x
Abbreviations
AC Alternating Current
AD Airworthiness Directives
AEW Aircraft Engineering Wing
AFCU Automatic Fuel Control Unit
AMM Aircraft Maintenance Manual
AMO Approved Maintenance Organization
AMP Aircraft Maintenance Program
AR & SS Aircraft repair and Salvage Section
ASB Alert Servicing Bulletins
ATA Air Transport Association of America
CAASL Civil Aviation Authority of Sri Lanka
CAMO Continuing Airworthiness Management Organization
CMM Component Maintenance Manual
CO Commanding Officer
CR & OM Component Repair and Overhaul Manual
CS Commanding Supply
DC Direct Current
DGCA Directorate General of Civil Aviation
EASA European Aviation Safety Agency
ELCH Elasticity of Laminate Checker
Ele & SPM Electrical Standard Practice Manual
EQRF Engineering Query Forms
FOD Foreign Object Debris
GPU Ground Power Unit
GRE Ground Run-up Enclosure
IEF In Flight Entertainment
IL Information Letter
IPM Illustrated Part Manual
LPI Liquid Penetration Inspection
MAF Modification Action Form
MFCU Manual Fuel Control Unit
MM Maintenance Manual

xi
MPD Maintenance Planning Document
MPI Magnetic Particle Inspection
NAITA National Apprentice & Industrial Training Authority
NDT Non-Destructive Testing
OC Officer Commander
OCL Officer Commanding Logistics
OEM Original Equipment Manufacturer
O I/C Officer In-Charge
OSN Operator Safety Notes
QAO Quality Assurance Officer
R & D Research and Development
RAD Repair Approval Design Sheet
rpm Revolutions per minute
SB Service Bulletins
SI Service Instructions
SLA SriLankan Airlines
SLAF Sri Lanka Air Force
SOAP Test Spectrometric Oil Analysis Program Test
Sqn Ldr Squadron Leader
SWC Special Work Card
TB Technical Bulletin
TP Technical Planning
UAV Unmanned Aerial Vehicle
USA United States of America
Wg Cdr Wing Commander

1
Chapter 1 – Introduction of Training Organization
1.1 Aircraft Engineering Wing
1.1.1 History and Introduction about the AEW
The Aircraft Engineering Wing of Air Force Base, Katunayake was declared open on
1st
of January in 1979 after reorganization of the Technical Maintenance Depot due to the
necessity of establishing a workshop to carry out the major repairs and services of every aircraft
belong to the all squadrons of Sri Lanka Air Force. Wg Cdr N Gunarathnam was the first
Commanding Officer of AEW and initially there were 02 Officers with CO, 05 Warrant
Officers, 26 Senior Non-Commissioned Officers, 07 Junior Non-Commissioned Officers, 41
Aircraft Men and 07 Civilians [1]. AEW was fulfilled with many capabilities after few years
and now there are twelve different bays. The repairing and servicing of Civil aircrafts under
special situations also conducted by the AEW crew.
All bays have wide scopes conduct repairs and services. All bays are administered
under an Officer Commander and a Warrant Officer In-Charge. AEW is capable of third line
maintenance, repair, services, overhaul and modification. Due to the depth of the maintenance
and servicing processes, majority of the technicians are represented by Senior Non-
Commissioned Officers.
There are several squadrons on the Katunayake Air force Base and the necessary
services and maintenance should be done in order to maintain the minimum number of aircrafts
per fleet. There were more squadrons during the war time period and now some of the
squadrons are not in active (Table 1.1). Basically, AEW is capable of giving services to No. 04
(VIP) Helicopter Squadron, No. 06 Helicopter Squadron, No. 07 Helicopter Squadron and No.
09 Attack Helicopter Squadron.
Figure 1.1 Aircraft Engineering Wing Crest

2
The crest of the AEW (Fig 1.2) is contained the motto, “Relentless support for the air
operation”. The propeller and the open-end tool represent the effort of aeronautical engineering
careerists to fulfil the aircraft engineering requirements on the efficient way through the
camaraderie.
1.1.2 Organizational Structure
The organizational structure of AEW is shown in Fig 1.2.
1.1.3 Nature of the Business and capabilities of Aircraft Engineering Wing
The AEW is the main authorized and qualified establishment for conduct the major
servicing, repairs and overhauls of the aircrafts and aircraft instruments of SLAF. Also, AEW
conducts the major repairs of every flying formations of SLAF which cannot be done from the
own workshops. There are various research and development projects aiming to enhance the
skills and knowledge of all personnel in AEW in order to encourage and guide them to increase
innovations.
Apart from the military maintenance, AEW maintenance crew capable enough to
provide technical practices to civil aviation organizations such as SriLankan Airlines and some
other private airlines. There is a programme of maintenance of aircrafts for the undergraduates
of the government universities as well as the trainees of Helitours.
Figure 1.2 Organizational Structure of Aircraft Engineering Wing

3
Present capabilities are as follows.
1 Aircraft mechanical component repair & overhaul
2 Aircraft instrument repair
3 Aircraft electrical equipment repair
4 Aircraft engine repair
5 Bell 212/412 helicopter major servicing
6 Aircraft structural repair & salvage
7 Helicopter rotor blade repair
8 Aircraft safety equipment servicing & repair
9 Non-Destructive Testing
10 Calibration of tools & equipment
11 Composite structures manufacturing & repair
1.1.4 Different Bays and Sections
Currently there are 12 different Bays/Sections in the AEW and they have their unique
capabilities and responsibilities in both air and ground operations.
1 Aircraft Repair and Salvage Section
2 Component Bay
3 Composite Bay
4 Electrical Bay
5 Engine and Propulsion System Bay
6 Instrument Bay
7 Non-Destructive Testing Lab
8 Rotor Bay
9 Safety Equipment Bay
10 Special projects Section
11 Standards Room (Metrology Room)
12 Wheels and Brake Section

4
1.1.5 SWOT Analysis
1.1.5.1 Strengths
Biggest strength of AEW as I feel is its experienced technical crew and high caring for
each other. Though their working environment is ruled under military system they are managed
to find the job satisfaction through their work on behalf of the motherland.
The main usefulness of the AEW it saves lots of money by overhauling helicopters.
AEW has full authority from the Bell Helicopter Textron Inc to rebuild crashed aircrafts using
fuselage jig and tail boom jig. If a helicopter has to dispatch to the mother company, that will
cost millions of rupees.
1.1.5.2 Weaknesses
The air power of the SLAF is now going down and AEW is based on mainly Bell 212,
Bell 412 and Bell 412EP helicopters only. Also, they have not capability to overhaul MI 17
and MI 24 helicopters. The technicians are trained under American type helicopters only. I
suppose if the crew has proper training about Russian helicopters, that will be much better.
1.1.5.3 Opportunities
There are several research opportunities for anyone who are willing to work with SLAF.
Mainly UAV project is the leading project that I had a chance to work with them closely for
few months in the Katukurunda Air Force Camp. Also, there are several projects in planning
based on design and manufacture pilot training aircraft in Sri Lanka. I hope these projects will
lead SLAF to a bright future.
Now AEW is based on the maintenance of the aircrafts and I hope one day these
maintenance practices will help to design and develop our own aircrafts using existing as well
as new technologies.
1.1.5.4 Threats
Higher cost of the components of the aircraft is the main threat as Sri Lanka is not a
rich country. The supply chain delays and lack of parts in the stores are other threats. There are
about 5 helicopters always in the maintenance line because of the lack of components. Also,
there is lack of trained aircraft technicians in the hanger. This will cause for a trouble in near
future after retirement of the current senior aircraft technicians.

5
1.2 Engineering Section, SriLankan Airlines (Ltd)
1.2.1 Introduction about SriLankan Airlines (Ltd)
SriLankan Airlines is the flag carrier of Sri Lanka and a member of the Oneworld airline
alliance based on Colombo. Its main hub is Colombo Bandaranaike International Airport
(CMB). Sri Lanka Airlines uses a fleet of narrow and wide-body Airbus aircraft and operates
a network of regional services within Asia and the Subcontinent as well as Middle East and
Europe. Sri Lankan Airlines is a small operator, in the commercial air transportation category
and uses its own DGCA and EASA Part 145 approved maintenance organization for the line /
base maintenance activities.
In the airline has Continuing Airworthiness Management Organization (CAMO) and
Approved Maintenance Organization (AMO). CAMO section is responsible for the
maintenance scheduling and controlling all the maintenance procedures. The AMO section
contains the maintenance crew who directly involved in the maintenance processes. Now
SriLankan Airlines expands its fleets types and number of aircrafts in order to increase direct
flights and number of flight routes and currently there are 105 destinations in 47 countries [2].
1.2.2 Brief History about the Sri Lankan Airlines
Air Lanka was established after the shutdown of Air Ceylon in 1979 with initial fleet
consists of two Boeing 707 leased aircrafts from Singapore Airlines. The wide-body operations
started with a leased Lockheed L1011-1 Tristar from Air Canada.
In 1998, Air Lanka was partially privatized with investment by Emirates group, when
Emirates and the Sri Lankan Government signed an agreement for 10 years. In 1998, the Air
Lanka re-branded to SriLankan Airlines. Those days, SriLankan Airlines had 6 Airbus A330-
200 and also A340-300 and A320-200 aircrafts. In 2008, Sri Lankan Government was seeking
greater control over the day-today management of the airlines so that in 2010 ended any the
affiliations the two airlines had with each other.
Figure 1.3 SriLankan Airlines Engineering Logo

6
In 2016 SriLankan Airlines undertook its low-cost Mihin Lanka into the mainline
brand. Mihin Lanka operated its final service on 30th
October 2016 and SriLankan Airlines
absorbed the relevant service network [3].
1.2.3 Organizational Structure
1.2.4 Nature of Business and Capabilities
Engineering Section capabilities can be divided into 3 sections, Engineering and
Support Services [4], Aircraft Maintenance Services [5] and Maintenance Support and
Component Repair Services [6]. Each section has their unique capabilities and authority from
Civil Aviation Regulation bodies such as Civil Aviation Authority of Sri Lankan (CAASL),
EASA [7] etc.
In Engineering and Support Services, the technical services from that section includes
continued airworthiness management support activities such as MPD analysis and Maintenance
Program preparation, SB and AD evaluations, management of modifications and repairs and
technical records. Also, it provides aircraft acceptance and delivery, asset management,
Figure 1.4 Organizational Chart of Engineering Section, SLA

7
reliability management and cabin appearance management services to the airline as well as
other airlines that are willing to get the service from SLA. Currently there are 27 different
aircrafts in SLA fleets of A320-214, A320-232, A320-251N, A321-231, A321-251N, A330-
243 and A330-343.
The SriLankan Engineering’s services have earned several approvals from the removed
civil aviation authorities and those are showcase of quality management of the section [8]. The
approvals are,
1 Civil Aviation Authority – Sri Lanka (CAA-SL)
2 European Aviation Safety Agency (EASA) Part 145 and Part 147
3 Civil Aviation Authority – Pakistan
4 General Civil Aviation Authority – United Arab Emirates
5 Civil Aviation Authority - Qatar
In aircraft maintenance services, there are two basic maintenance places, line and base. The
line maintenance team is capable to provide comprehensive maintenance services at CMB and
at key airports in South India and Male. The base maintenance facility has about 400 well
trained skilled personnel in hangar and fully equipped to carry out heavy maintenance of
narrow-body and wide-body aircrafts.
Maintenance supports and component repair services is equipped with EASA 145 certified
workshops. These workshops have their unique capabilities and responsibilities with. Some of
the workshops are as follows.
1 Metallic Structural Repair Workshop
2 Composite Structural Repair Workshop
3 NDT Workshop
4 Wheels & Brakes Workshop
5 Cabin Workshop
6 Safety Workshop
7 Paint Workshop
8 Accessories Workshop
9 Avionics Workshop

8
The Engineering Section of the SLA provide services to the other airlines when there is a
request from them. The engineering section is an outstanding and award-winning MRO in the
globe.
1.2.5 SWOT Analysis
1.2.5.1 Strength
Biggest strength of the SriLankan Airlines as I feel is its high caring for employees. It
has very friendly and open environment where employees are treated extremely well. As every
worker related with the aircraft maintenance are bounded to the regulated human factor rules
and so that everybody enjoys job satisfaction in the maintenance field.
1.2.5.2 Weaknesses
I suppose there are not enough maintenance crew in some workshops because of the
higher workload. If there is new recruitment of aircraft technicians will help to increase the rate
of supply to the stores. Also, the younger aircraft technicians are in small number and most of
the technicians are in their middle age. That will also cause to increase the time to finish the
tasks.
1.2.5.3 Opportunities
SriLankan Airlines AMO section has capability to repair major and minor repairs of
other airlines as they have EASA part 145 approval. So that by providing services to others can
be a way to increase the profits. In recent past SLA had provide their maintenance facilities to
airlines like IndiGo and now they can start that again.
1.2.5.4 Threats
I suppose the main threat is the lack of aircraft technicians because most of them are
working here to gather required experience to immigrate and work for the foreign airlines. That
is the main reason for the low number of the younger technicians. The management should
have a proper plan to reduce this effect and in future this will be a problem.

9
Chapter 2 – Training Experience
2.1 Aircraft Engineering Wing
I have worked for 10 weeks starting from 2nd
of June 2018 to 07th
of September 2018
in the AEW. I have been assigned to different sub sections and workshops and practices
basically helicopters and aircraft component inspection, repairing, modification and overhaul
by referring different documents that were published by manufacturers and suppliers. Also, I
have observed some operations in different checks in aircraft, log books maintaining processes,
technical record. Here are the workshops I have worked under the guidance of the technical
instructors. Safety equipment such as masks, safety gloves, safety goggles, ear protectors were
supplied by the stores in the AEW.
2.1.1 Aircraft Repair and Salvage Section (AR & SS)
I have been assigned to the AR & SS for 15 days (3rd
of July – 24th
of July) as the
schedule given by the technical and planning section. AR & SS is capable to carryout minor
and major structural repairs of all the aircrafts in the SLAF, jig repairs for fuselage and tail
boom of Bell 206, Bell 212, Bell 412 and Bell 412EP helicopters, aircraft recovery and salvage
operations and some structural modifications as mentioned in CMM and AMM. By the OEM.
2.1.1.1 Machines, Tools and Equipment
The maintenance of the structures is completing by maintaining original strength,
maintain original contour and shape and minimizing weight. There are lots of tools and
equipment in that section. Machines and equipment that I worked can be categorized in the
sections that they are used. These sections and some of the tools are in the table 2.1 [9].
Table 2.1 Tools and Machines used in AR & SS
Category of tools Tools and equipment that are used
Layout tools Scale, Divider, Rivet Spacer
Cutting tools Cut-off wheel, Pneumatic circular saw
Shop tools Squaring Shear, Throtless Shear, Scroll shear, Notcher
Hand cutting tools Files, Aviation Snips, Die Grinder, Burring tools
Drilling machines Portable drill motor, Pneumatic Drill motors
Forming tools Slip roll former, English wheel
Shrinking & Stretching tool Cornice Brake, Hand operated shrinker
Riveting tools Pneumatic rivet gun, bucking bars, rivet cutter

10
2.1.1.2 Aircraft Materials
Most of the materials that are used in the Aviation field are Aluminum alloys. They are
in different heat treatment conditions and for some repairs, harder materials like Titanium and
Steel based alloys are used. The type of material and heat treatment condition is mentioned in
the AMM and CMM. If new component has to be manufacture, there use T0 material and after
that it heat treated by using oven in the AEW.
Materials can be identified using the code in the sheet. I have learned how to read and
understand the composition of the material and heat treatment condition.
2.1.1.3 Types of Rivets and Fasteners
There are several types of rivets and fasteners in an aircraft. The difference among the
rivets in heat treatment condition and the material type. Also, other fasteners that are not
categorized under rivets have their own characteristics. The positions of applying those rivets
are mentioned in the CMM and AMM descriptively. Here we have familiarized with Cleco
fasteners types, applications, riveting and de-riveting [10].
2.1.1.4 Hands on Experience
There are two different types of structural repairs I have practiced under the guidance
of the aircraft technicians. They are patch/ panel repair and flush repair. Patch repairs are the
most common types of repair in aircrafts because that is easy to do. Flush repairs are done in
the critical components such as leading edge of the wing, control surfaces etc. The rivet
calculation method and edge distance calculation method are little bit different for those
repairs.
For the practical, Sgt Premalal gave a cracked plate and asked to design panel repair.
Also, for another practical, we have to design flush repair for a given cracked plate. In the real
scenario the dimension of the crack should be measured and compared with the CMM if it is
within the limitations. If it is not, whole component should be replaced.
In the preparation of the repair, we have calculated the rivet size and length after
measuring the required length by using rivet gauge. Using that calculation, the size of the drill
bit was selected. Stop holes drilled at the end of the crack and wholes pattern marked in the
sheet. The repairing sheet was cut for the required size and filed the edges to reduce stress
concentration. After that, drilled the holes in the cracked sheet and using Clecos, transferred
them in to the other sheet. Then riveted the prepared rivets using rivet gun as well as using
mallet.

11
I have practiced the de-riveting process with the highspeed cutter machine and transfer
punch. In the flush repair, two repairs should be prepared. Other fastener types and de-riveting
procedures were practiced in the same manner.
In the line bending process, we have used line bending machine. The preparation of the
metallic component and calculation for the minimum bending radius, bending allowances was
demonstrated. Also, we have operated that machine and got hand on experience on the line
bending machine.
2.1.2 Composite Bay
This section is capable of inspection, repair and modification of the aircraft composite
parts and also, they fabricate components of UAV manufacturing. I have worked 1 day (18th
of
July) here under the supervision of F/Sgt Muthukumarana.
2.1.2.1 Types of materials
There are several composite materials that are used to fabricate panels and repairs
according to the OEM. Material types that are using in the composite section are as follows.
1. Honeycomb
2. Dry glass fabric
3. Dry carbon fabric
4. Vacuum bagging film
5. Breather cloth
6. Peel ply cloth
There are several grades of each material. We had opportunity to assist to fabricate seat
for Y12 aircraft using wet layup procedure under the guidance of the aircraft technicians.
2.1.2.2 Vacuum Bagging procedures.
First, prepared the materials to be laminated. Cut 2 glass fabric layers to shape and
placed them for wet-out. After that cut the release fabric, breather material, vacuum bag to size.
The size of the vacuum bag is about 20% larger than the mold. Then coat of gelcoat was applied
to the mold and allowed it to cure. That will help for good base for paint and prevent print
through” of the fabric.
Then mastic sealant was applied to the mold perimeter. In that process, applied firm
pressure and overlapped the ends so there were no gaps. The space around the laminated area
was leaved and kept the paper backing in place on the mastic. That helped not become
contaminated with wet epoxy.

12
Layers of glass fibre fabric was placed in position on the mold. After epoxy is mixed,
the time limit for the entire process is established based on the hardener used, ambient
temperature and the volume of laminate in the mold. After it was wet out, squeegeed excess
epoxy from each layer of fabric. There should be no puddles of epoxy or air pockets under the
fabric because fabrics are compressed when vacuum bagging and so less epoxy is required.
After that placed layers of relies fabric over the laminate. Release fabric will peel off
the cured laminate leaving a fine-textured surface also excess epoxy will be removed along the
release fabric. Breather material placed over the release fabric. This layer allowed air to pass
through its fibers to the port and helped to absorbs excess epoxy that passed through the release
fabric.
Vacuum bag placed over the mold and seal it to the mold’s perimeter. The excess bag
was sealed. Vacuum line was connected to the bag with a vacuum port. Punctured small hole
in the bag and attached the port to the bag over the hole. Several layer of breather material
layers placed under the port. Then turned the vacuum pump on to evacuate air from the bag. It
remained for about 8 hours continuously. After the laminate had cured thoroughly, removed
the vacuum bag, breather and release fabric. The removed part was finished to get the proper
shape and corrections [11].
2.1.3 Non-Destructive Testing Lab
I have worked in the NDT lab for 4 days (1st of August – 6th of August) and practice
several NDT test methods. There are 6 different inspection capabilities for the NDT lab in
AEW and I had opportunity to operate most of the machines.
Figure 2.1 Typical Components of a Vacuum Bagging System

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2.1.3.1 Visual Inspection
The most basic and most common technique that use in NDT that use some equipment
to enhance the visual testing. Some of the equipment that use are dental mirrors, magnifiers,
borescopes and videoscopes. This inspection process is limited to detect surface cracks and
dents up to some extent due to the sensitivity limitations of human sensory system
2.1.3.2 Liquid Penetration Inspection (LPI)
This method is easy, fast and low-cost method to detect defects on the surface of any
material. Visual inspection should be done prior to the LPI to identify defects. There are several
steps should follow for this inspection.
1. Pre-cleaning of the surface
2. Apply penetrant and keep dwell time
3. Remove excess penetrant by using solvent
4. Apply developer and keep dwell time
5. Inspect test surface
6. Post cleaning of the surface.
There are two types of LPI red dye inspection and fluorescent inspection. If the
penetrant type is red-dye, the cracks can inspect without using especial light condition. But
when fluorescent inspection is used, that should examine under UV light. But the sensitivity is
higher in fluorescent inspection rather than red dye inspection. There are 4 types of method in
the solvent removing method differ from chemical type that used. They are,
A – Water washable
B – Post-emulsifiable – Lipophilic
C – Solvent removable
D – Post-emulsifiable – hippophilic
The most sensible method is fluorescent type method C inspection. The required type
of inspection and method is mentioned in the CMM and AMM. If there is no predefined method
or type, the NDT section use fluorescent type method A.
A welded plate was inspected to detect cracks on the welded are using fluorescent type
method A. First the plate was cleaned well to remove contaminants on the surface. Then applied
penetrant by spraying and keep 5 – 10 minutes as dwell time. Then excess penetrant was

14
removed by clean rag. After that developer was applied and keep it for 5 – 10 minutes as dwell
time. Then wiped developer on the surface and inspect the surface using UV light.
After the inspection was over surface is cleaned to remove chemicals which are used to avoid
corrosions.
2.1.3.3 Magnetic Particle Inspection (MPI)
MPI test is to detect surface and near surface cracks of objects. The test pieces should
be ferromagnetic material because object should have ability to magnetized. Magnetic flux is
created in the ferromagnetic material when supply current flow through. When there is any
defect in the test object surface and the ferromagnetic particles are gathered around the crack.
Magnetizing Bench Method, AC/DC yoke method are two different methods in NDT section.
2.1.3.3.1 Magnetizing Bench Method
This machine contains two sections, head shot and coil shot (Figure 2.2). Test piece
should be kept between those two and dc current supplied discrete or continuous manner while
test piece is covering with mixture of fluorescent magnetic particles and water. UV light is used
to inspect the contaminated magnetic particles on the test piece. Test bench was converted for
the ease of inspection. Head shot can be used to inspect longitudinal cracks on the test object
and coil shot is used to inspect transverse cracks.
2.1.3.3.2 AC/DC Yoke
The yoke has two jaws that can be used to magnetize materials using AC or DC (Figure
2.3). In the testing process, test piece cleaned and dried before inspection. Then dry
ferromagnetic power was spread on the test piece and yoke moved in zig-zag pattern on the
test object. If there is a crack in between two jaws, those powder converged into that cracks
because cracks are disturbed to the magnetic flux.
Figure 2.2 Magnetizing Bench

15
AC and DC supply are used in different purposes according to the surface cracks. AC
supply is used to inspect surface cracks and DC supply is used to inspect sub surfaces.
After the observation, all test pieces should be demagnetized using demagnetizer because there
will be residual magnetic field on the pieces. That will cause to avoid corrosions. I have done
several practices using this machine and identified cracks on metallic structures
2.1.3.4 Eddy Current Inspection
This method is the mostly used NDT inspection method in aviation field. The structure
that is going to inspect using this method should be conductive object and electromagnetism is
the basic principle and defects are identified using the difference of the signal pattern of
calibration block and test object. Difference probes are used according to the material and the
shape of the object. Most commonly used probes are direct and 90⁰.
Rather than find deforms of the material, this method can be used to identify corrosion,
conductivity, material type and paint coating thickness. We have assisted to check defects on
rotor hub of Bell 212 helicopter using this method.
Figure 2.3 Inspect using AC/DC Yoke
Figure 2.4 PHASE 2D Eddy Current Test Machine

16
2.1.3.5 Ultrasonic Inspection
Ultrasonic waves with high frequencies greater than 20 Hz are used in the Ultrasonic
inspection. Ultrasonic waves are transmitted into the test object and the reflection wave is
monitored using machine. This method can be used to detect cracks, corrosions, measure
thickness in the test pieces. There are two main techniques that we have used in the inspection
processes. They are Pulse echo technique, through transmission technique. There are specific
methods and procedures to calibrate probes and get the reference distances.
The probe is made by piezoelectric material. This method can be used detect near
surface and sub surface defects. The near field distance can be reduced by using dual probe.
To increase the contact and avoid air bubbles I have assisted to check defects on main rotor
blade hub grip of Bell 212 helicopter.
2.1.3.6 X-Ray Test
There are specific components that should be inspected using X-Ray test. This method
is mostly used in Y12 aircraft rather than Bell helicopters in the SLAF. We haven’t a chance
to get experience with the X-ray test but instructors demonstrated the process step by step.
The machine, ERESCO MF4 Portable Industrial X-ray Generator [12] is used in the
SLAF (Figure 2.5). For the safety of the operators and others, placards and red warning lights
are displaying in the surroundings while operating the machine and machine is operated in the
lead cupboard. Radiation survey meters are worn by every people in the surrounding area.
During that time period, AEW is evacuated.
X-ray machine kV range and exposure time is setup according to the thickness of the
material, material type. X-ray films are prepared according to the required size. The film
processing process is done under the lower frequency light condition, basically under red light
Figure 2.5 ERESCO MF4 Portable Industrial X-ray Generator

17
condition. First films are hanged on hangers and then dipped in the developer. After required
time, film was taken out from the bath and observed.
There are standard symbols and details that should be mentioned in every x-ray film
and for that lead letters are used. Also, there is an intensity meter to check the sensitivity of the
x-ray shot in order to identify the cracks.
2.1.4 Engine and Propulsion System Bay
This section, simply named as Engine Bay is one of the most significant section in the
AEW. I have been there for 4 days (7th
of August – 10th
of August) under the supervision of
F/Sgt Sanath.
2.1.4.1 Kfir Test Cell
Kfir test cell is used to check the engine performance of the J79-J1 engine, which is the
engine type of Kfir aircraft, prior to install in the aircraft. The ground test run performance is
measured after overhauling an engine. Page Avjet Cooperation in USA is the manufacturer of
that test cell. There are several components in that test cell such as cockpit, thrust trailer, fuel
tank, power unit.
Cockpit is used to monitor the running condition of the engine. This room was designed
as the cockpit of the aircraft and there is additional measuring equipment rather than in the
fighter jet cockpit. This test cell has capability to monitor the afterburner performance of the
engine also. There are only several officer who have authority and capability to run the test
cell. Unfortunately, this test cell is now not in running condition because SLAF is not further
depend on Kfir aircrafts, but there are 2 aircrafts in running condition because this squadron
has Presidential Colours.
2.1.4.2 Dynamically balancing of Compressor turbine
The procedure of dynamically balancing compressor blades is demonstrated by an
aircraft technician. SCHENKHL2B machine is used to measure vibration of the compressor
turbines. The assembled compressor turbine is attached to the machine and luminous sticker
was pasted on a blade. Then laser sensor was adjusted to that sticker. When the turbine is
rotated, the sensor was able to detect the rpm After that machine calibrated the rotation and
shows the weight reduction or weight addition amount as required.
There were pre-defined setups for each turbine and compressor dynamically balancing
for each engine types.

18
2.1.4.3 Videoscope and Borescope
Videoscope inspection of Y12 aircraft engine was observed in the Engine Bay. This
method is a type of NDT visual inspection method. This method was used to identify defects
in compressor blades without disassembling the engine components. The display is connected
to the probe which end has light source and camera. That probe can be bend rotate using
joystick that was controlled by the observer. I had a chance to inspect and get the experience
of the inspection of the compressor blades.
2.1.4.4 Turbine blade riveting and de-riveting
There is a special machine use for turbine blade riveting and de-riveting because that
process should be high accurate because the loss of weight of the assembly disc cause for
vibrations.
We have observed the process of riveting and de-riveting process of PT6-3TB engine
turbine blade. In the de-riveting process turbine disk was fixed on the base which is inclined
22⁰ 30” to the surface. The drill bit descending height was adjusted to 0.092” because the
thickness of the plate is 0.092”. Then the base was lifted till drill bit and base touch each other.
After that drilling process was conducted.
In the riveting process, the turbine disk was fixed to the base at an angle of 22⁰ 30”.
Then rivet placed in between plate and hammer and apply 875 psi – 925 psi. The riveting
process was done under those conditions. After finishing the turbine blade set, that should be
dynamically balanced by using the machine.
2.1.4.5 Spectrometric Oil Analysis Program (SOAP)
This is the method to detect the amount of metal particles in the aircraft engine oil, that
can be used to identify the wear of components inside the engine without disassembling it. If
the specific metal particle concentrate is higher than usual amount, that’s mean there will be
some worn components. The testing cycle time is different from aircraft type as mentioned by
OEM. As an example, fighter jet like Kfir aircraft oil sample was checked after every flight
cycle and Bell 212 helicopter oil sample was checked in the scheduled checks.
There are two machines for SOAP, one is BIRD MOA which is specially used to
analyze Kfir aircraft oils and other one is a Universal SOAP machine. The main method of
these machines is burning oil using sparks of carbon electrodes and then identify
electromagnetic spectrum. We have done SOAP practical using universal machine.

19
First the machine was calibrated by using sample oil given by the manufacturer. The
carbon electrodes were sharpened and fit to the machine. Then oil sample is set to the machine
and start the process. If the machine showed the amount of metal contaminate in the given
range of the sample bottle, calibration process was over. Then the process was repeated by
using aircraft oil sample and check the metal limitation with the CMM of the engine.
2.1.5.6 Design a puller
I have worked with Sgt Rathnayaka who works as an aircraft technician in Engine bay to
design a puller to remove the outer covering of the PT6-3T type engines. The details are
attached in the Annex 1.
2.1.5 Safety Equipment Bay
This section is capable of inspecting, servicing and repairing of different safety
equipment such as parachutes, life rafts, life jackets, anti-G-suits, medi-packs etc. I have been
assigned for 3 days (13th
of August – 15th
of August) in this section under the supervision of
F/Sgt Buddadasa.
2.1.5.1 Parachutes
There are several parachute types in that are used in the SLAF and they differ from the
type of aircraft, passenger and place. There are mainly four types of parachutes, seat type, chest
type, back type and headrest type. The configuration is different in the pilot seat configuration.
The main type of parachutes in the safety bay are as follows.
Table 2.2 Emergency parachute types in the SLAF
Parachute type Aircraft
BMK – 72 Worrior, Siamarchetti
JS – 3 PT6
JS – 7A FT – 5
JS – 10DP FT – 7, F7
MK – 10 Kfir
JSS – 16A K – 8
JS – 3 parachutes are the most common used parachute. All parachutes are unpacked
after some time period as mentioned in the manual. They are hanged for several days to dry
and inspect under special environment and packed again in special procedure. I assisted to pack
parachutes.
First parachute was kept on the table which was specially used for that process. Then
the withdrawal line was fixed to the hook at the end of the table. Then parachute lines were

20
cleared. There are 28 rigging lines for a parachute and lines were laid into two sets. Using
rigging hook, parachute was carefully packed in specific pattern. This pattern is caused to slip
the rigging lines without blocking.
Drogue chute is used to pull the sleeve when the opening of the parachute. Other tools
are packing frame and packing stick. The harness was tightened by scarlet thread after packing
the parachute to easy operation of the parachute.
JSS – 16A parachute is used in the K – 8 aircraft and this is headdress type. This
parachute is different from the normal JS – 3 parachutes by the method of packing of the drogue
chute. The drogue chute was packed in the special section in the parachute container. The main
purpose of that drogue chute is to pull the sleeve and descend the ejection seat up to the
predefined altitude. The container was pressurized about 24 hours to roper packing by using
special equipment.
Apart from that there is another type of chute called drag chute that is used to reduce
aircraft speed and assisted in breaking operation of fighter aircraft. This equipment is not re-
packing in safety equipment bay and that capability is for the relevant squadrons.
2.1.5.2 Survival Packs
Survival pack is in some of the aircrafts in SLAF and there are several types. One type
in fighter aircrafts, survival pack is placed under the pilot seat and another one is inside life
rafts. Survival pack is designed regarding the number of crew. I have assisted to insect and re-
packing of survival packs.
The component types are number of components and changed according to the
requirement. The main components in survival pack are dry ration, first aid kit, drinking water
bag, flare pistol and flares, sun reflector, torch, whistle, compass. Knife, location beacon, shark
repellent, medical kit for venoms etc. Most of the equipment have expiration period and so that
they have to be inspect and replace those components.
2.1.5.3 Fire Bottles
The capabilities such as inspection, repair, replace and recharge of the aircraft fire
bottles are in the safety bay. Here I have observed the refilling process for a fire bottle that used
in the Bell 212 helicopter. Fire bottle was filling with the Chaldon 114B2 as the chemical. There
are 4 manifolds and 2 electrically operated cartages for each manifold to operate the fire bottle.
Mainly they are placed in the engine decks.

21
First fire bottle was visually inspected for corrosions, dents, cracks etc. and if there
were any defects, those fire bottles will dispatch for repairs. Corrosion removal and repainting
process is done in the safety bay if these are within the limitations.
The fire bottle was submerged in a water container and pressurized using N2. The
technicians must wear safety gloves, body armor during that process. After filling the bottle,
keep for 48 hours to inspect pressure inside for leaks.
2.1.5.4 Anti-G-Suit
A G-suit is an anti-gravity garment worn by fighter pilots. When they are pulling
positive G’s, the suit inflates using intake air and prevent blood from pooling in their feet and
legs which would cause them to lose consciousness [13]. We have observed this garment in the
safety bay.
2.1.5.5 Life jackets and Life rafts
Life rafts and jackets are used when aircraft is landed to water or crashed and fall in to
water. Passengers and crew can use them to save their lives. The fighter aircraft pilot is wearing
that jacket throughout the flying time and other aircrafts have life rafts. The jacket is with a
cartridge to inflate contains whistle, location indicator etc.
The capacity of the raft is chosen according to the maximum number of passengers in
aircraft. They are one personnel, two personnel, for personnel, twenty personnel, sixty
personnel etc. [14].
I have assisted to inspect and repack in the safety bay. There is a survival pack in the
raft. Compressor was used to inflate and air blower is used to delate the life rafts.
2.1.6 Electrical Bay
This section has authority to service, repair, overhaul and modify electrical equipment.
I have been assigned to this workshop for 2 days (17th
of August – 20th
of August) under the
supervision of F/Sgt Perera CAS.
2.1.6.1 Ground Power Unit (GPU)
GPU is used to give power to initially start the engine of aircraft without using aircraft
battery. This can give 115 V, 400 Hz AC or 28 V DC power. Higher frequencies of current are
used to smooth the current when the GPU gives AC power. There are several types of GPUs
in SLAF as Hauchin, Guinault, Hobart and Trielectron. I have observed the functionality of the
GPU and assisted to repair a GPU.

22
GPU has a generator powered by a diesel engine. The battery which is in the GPU is
used to initially provide a current path to the starter motor and primary stator. The mechanism
is the electric generator mode and there is diode plate which uses to control the three-phase
current produced by the machine.
The most of the damages are caused due to unawareness transportation. Common snags
are damaging armature and secondary winding. This is happened because of the clearance
between the armature and secondary stator is very low.
2.1.6.2 Starter Motor
I had chance to assemble and disassemble a starter motor of Bell 212 helicopter. This
starter motor is used also in Bell 412 and Y12 aircrafts. This process was instructed and guided
by F/Sgt Perera CAS.
2.1.6.3 Battery Charging
Nickel Cadmium batteries are widely used in the aircrafts of SLAF. They are charged
using THE SUPERSEDER IIA Nickel-Cadmium Battery Charger Analyzer. This battery
charger was not in working condition in the time period we were there. The charging condition
can be set and monitored should maintain the temperature rise of the batteries to avoid thermal
runaway [15]. This charger has capability to charge 2 batteries at once.
Thermal runaway occurs in the situation where an increase in temperature changes the
conditions in a way that cause a further increase in temperature. It is associated with strongly
exothermic reactions that are accelerated by temperature rise. Also, that increase the current
Figure 2.6 General Mechanism of the GPU

23
flow by reducing the resistance. That will damage the battery cells and cannot recover after
happen.
2.1.7 Instrument Bay
Instrument bay of AEW carry out calibration and repair of all types of aircraft
instruments such as altimeters, airspeed indicators, vertical speed indicators, artificial horizon
etc. I was in that workshop 1 day (21st
of August) to get an idea about the equipment procedures
and methods.
2.1.7.1 Micro Manometer
This equipment was manufactured by Glass Development Limited, London and is a
pressure operator flight instrument tester that is used to calibrate the altimeter and ASI.
2.1.7.2 Altimeter
This practical was done by using the master altimeter. The real statuses should be given
when calibrate the altimeter. Micro manometer and vacuum chamber were levelled and master
altimeter kept inside the chamber. After that the door was locked and chamber was sealed.
Static line of the micro manometer was connected to the chamber and the height was selected
as 29.92” Hg and check the reading when it is on the ground. The static line of the micro
manometer was connected to the chamber and adjusted till the meniscus of the mercury column
comes to the level lines. The height was selected above 1000 ft height (28.86” Hg) and carried
out the process and 2000 ft height. Adjustments can be done with internal screws and links.
2.1.7.3 Air Speed Indicator (ASI)
ASI can be calibrated by using micro manometer and digital pressurizing instrument. I
have observed the ASI of Y12 aircraft. In the first method, ASI was kept inside the chamber
and pitot line was connected to the chamber. By changing pressure of the monometer, calibrate
Figure 2.7 Micro Manometer

24
the manometer. In the second method the pressure line was connected to the machine and
observed the readings by changing the pressure values.
2.1.7.4 Vertical Speed Indicator (VSI)
To calibrate VSI, ROCI tester is used. ROCI tester is also a pressure operator flight
instrument tester as the micro manometer. Here the rate of climb was measured by minutes per
meter or minutes per feet. By applying pressure difference to two valves in the VSI calibrated
the equipment.
2.1.7.5 Artificial Horizon (AH)
MK 4A Gyro Tester [16] was used to calibrate the AH of Cessna 150 aircraft which we
have observed. The gyro tester was levelled by looking through the bull eye and AH was
connected to it. Then suction valve of the gyro tester was connected to the AH because the AH
is an air driven gyro. The levelling adjustments were done by adjusting the levelling screw
while suction was in progress. The process was done repeatedly until AH levelled.
2.1.7.6 Aircraft Weight and Balancing
Aircraft weight and balancing is carried out after major maintenance, modification,
major component change and also hard landing as mentioned in the AMM. There are three
weighting methods to weight and balancing the aircraft.
1 Pad – Landing gears of the aircraft should be on the pads. This method is used
for mainly on fixed wing aircrafts.
2 Hanging – Aircrafts like Chipmunk comes under this method.
3 Load cells – In this method aircrafts should be jacked from the jacking points
after keeping the load cells on the jacks.
There are several steps that should assured before weight and balance process.
1. Fuel should be drained.
2. Every components of the aircraft should be installed
3. Weighing should be done in an enclosed area
4. Aircraft should be levelled in longitudinally and laterally.

25
The procedure of Load cells was described by the aircraft technicians. An electrical measuring
unit is used to level the aircraft. Weight of the helicopter was measured by the control unit and
calculated the CG from the datum point. CG should be in the range that was given by the OEM.
For the corrections, ballast units were applied to pre-defined sections in the aircraft. The main
point is in the nose section and also in the engine deck section.
2.1.8 Special Projects Section
This section undertakes the 1000 hours or 5 years servicing of Bell 206, Bell 212, Bell
412 and Bell 412EP helicopters re-building after repairing and re-wiring of above helicopters.
I have been assigned to this section for 16 days (24th
of July – 31st
of July & 23rd
of August –
6th
of September) under the supervision of F/Sgt Jayasundara & F/Sgt Upul.
Aircraft technicians categorized to several categories as follows.
1. Air frame – responsible of aircraft structural components, flight control systems,
landing gear system, hydraulic system, main roto and tail rotor drive system.
2. Electrical & instruments – responsible of electrical instruments and re-wiring
process
3. Engine – responsible for engine and propulsion system.
4. Radio – responsible for navigation and communication system
2.1.8.1 Aircraft Systems
There are several sub systems that we have worked with the and get hands on
experience. We had chance to interact with inspect, repair, overhaul, modification processes
on those systems. We worked in PT6-3TB and PT6 – 3TD model engines in the Special project
section.
Figure 2.8 Jacking by load cells

26
2.1.8.2 Oil System
The basic introduction about the Oil system was given by F/Sgt Upul and after that we
had chance to assist in maintain processes.
The pressure system inside the accessory gearbox. The scavenge system consists of
three gear type pumps and one ejector pump. The oil drained into the accessory gearbox by
gravity effect and also by a gear-type pump.
The Pressure adjusting valves are used in the system to provide accessible external line
oil pressure adjustment the top of the accessory gear box. Pressure regulating valve and check
valves are there to prevent static oil flow from airframe oil cooler back to power section oil
tank. The oil filter and bypass valve provide oil filtration for the power section and the
reduction gearbox. We had observed those sections and assisted to maintenance processes that
carried out.
2.1.8.3 Fuel System
This system is to provide the engine with clean fuel at the required pressure and flow
to permit control of engine power. There are several major components in that section such as
fuel heater, fuel pump and filter, Manual Fuel Control Unit (MFCU), Automatic Fuel Control
Unit (AFCU), fuel accumulator, flow divider, fuel nozzles, power turbine governor, Torque
control unit, etc.
Fuel heater is to hear the fuel to prevent ice crystal formation in the fuel filter. This is
oil to fuel heater and thermal element reacts to fuel temperature and moves a sliding valve to
control the amount of oil flowing into the heat exchanger. Fuel pump is to provide clean fuel
under pressure to the fuel control unit.
MFCU is one of the important components in the fuel system. It in automatic mode,
directs the fuel from the pump to the AFCU and then from the AFCU to the fuel nozzles. In
manual mode, calibrate and directs the fuel from the pump directly to the fuel nozzles. AFCU
establishes the proper fuel schedule according with intake air, twist grip and power turbine
inputs.
Fuel nozzles are used to deliver atomize metered fuel into the combustion chamber.
There are 14 fuel nozzle adapters (7 primary, 6 secondaries and 1 inlet). The primary and
secondary nozzles can be identified by the welding dot in the secondary fuel nozzle.

27
2.1.8.4 Helicopter Inspection
There are several inspection procedures in the AEW. Most of the inspections are
scheduled ones and some of them are unscheduled inspections. Bell helicopters are servicing
according to the schedule that was given by OEM considering flying hours and years as
follows.
1. 3000 hours servicing / 5 years inspection
2. 1000 hours servicing
3. 600 hours servicing / 12 months servicing
5. 100 hours servicing / 12 months servicing
7. 25 hours servicing / 30 days servicing
1000 hours serving and 3000 hours servicing are 3rd
line maintenance and aircraft
should come to the AEW. Others are 2nd
line maintenances. So, each squadrons and hangers
have facilities to do that maintenances.
The unscheduled inspections are done after very serious incident was happened as
mentioned follows.
1. Hard landing
2. Sudden stoppage main rotor or tail rotor
3. Over speed main rotor
4. Over torque main rotor
5. Lightning strike
We got an idea about 1000 hours service in Bell 212 and Bell 412 aircrafts
2.1.8.5 Aircraft preparation for inspection
When an aircraft initially come to the AEW for inspection, few experienced aircraft
technicians fly with the pilot to identify snags and faults. Then aircraft should be preserved by
cleaning the fuel lines with oil because that helicopter grounds couple of months and prevent
corrosion. To that fuel lines were disconnected by the fuel tank and set to the oil container.
After that engine cranked without starting.
Then all fuels are removed from the aircraft and tugged to the hangar. After that
disassembling process was started.

28
2.1.8.6 Helicopter Rotor Blade Removal
The first component that removed from the aircraft is rotor blades. There are 2 rotor
blades in Bell 212 helicopters and 4 rotor blades in Bell 412 and 412EP helicopters. The
mechanisms are similar but there are slight changes about them. We have assisted to
disassemble rotor assembly from Bell 212 helicopter and Bell 412 helicopters. Here swash
plate mechanism was described by an aircraft technician.
Swashplate is a devise that translates input via the helicopter flight controls into motion
of the main rotor blades.
2.1.8.7 Aircraft Log Book
There are 2 unique log books for each helicopter in the SLAF. They are called as “Form
700 traveler” and “Form 700 current”. Every maintenance details and observations about the
aircraft should record in that log books. Form 700 current log book is in the mother squadron
and Form 700 traveler is in the aircraft. When an aircraft came to servicing, Form 700 traveler
hand over to the AEW to carry out inspections and maintenance procedure.
When a helicopter is completed the maintenance process and ready to hand over to the
squadron and also before starting a flying cycle, there are 6 divisions has to sign indicating that
the helicopter is safe to fly. These 6 sections are
1. Armament Safe
2. Airframe
3. Engine
4. Electrical and Instrument
Figure 2.9 Swash Plate Mechanism

29
5. Air Radio
6. Safety Equipment
Experienced aircraft technician from each section should carefully inspect and sign that
document. After that pilot signing and hand over the helicopter.
There are 10 independent checks in various situations to do. Some of the checks are to
extend the life of the helicopter before next overhaul.
1. Leading particulars (LP)
2. Limitation certificate (LS)
3. Special trial fit certificate (STFC)
4. Acceptable deferred faults certificate (ADFC)
5. Service and component life extension certificate (SACLEC)
6. Fitness of the flight and after flight certificate (FF & AFC)
7. Replacement certificate (RC)
8. Flight servicing certificate (FSC)
9. Maintenance work certificate (MWC)
2.1.8.8 Helicopter maintenance documents
There are several documents that original manufacturer and component manufacturer
issued for the reference of the technicians. Relevant documents should be with the technicians
with the relevant task.
1. IPM – Illustrated Part Manual
2. ASB – Alert Servicing Bulletins
3. MM – Maintenance Manual
4. CR & OM – Component Repair and Overhaul Manual
5. TB – Technical Bulletin
6. IL – Information Letter
7. OSN – Operator Safety Notes
8. SI – Service Instructions
9. Ele & SPM – Electrical Standard Practice Manual

30
2.2 SriLankan Airlines Engineering Section
I have worked for 14 weeks starting from 10th of September 2018 to 14th of December
2018 in the SriLankan Engineering. I have been assigned to different sub sections and
workshops and get an idea about the fixed wing aircraft inspection, repairing, modification and
overhaul by referring internal and external documents of the SLA such as CMM, AMM, SB,
CAME etc. Also, I got hands on experience from some workshops and observed works. The
task card issuing process and maintenance scheduling process is observed and identified the
key characteristics in the aviation field. I have worked under the proper guidance of aircraft
technicians, approve holders and aircraft maintenance engineers.
The different sections and subsections that I have worked and experience that I gained
is described in the later sections.
2.2.1. Technical Services
I have assigned to the technical service section in for 3 days (10th
of September – 12th
of September). Technical service section is where the Aircraft Maintenance Program (AMP)
in such a way that ensuring the continuing airworthiness of the aircraft. Also, this section
handles the CAMO function in the SriLankan Airlines in order to comply with the Part M
regulatory requirements.
Each section checks major and minor modification of the aircrafts according to the SB,
MAF, SWC documents. Also, if there is a problem beyond the scope given to the MRO,
technical service takes necessary actions to solve the problem by issuing EQRF form and find
solutions with the help of Airbus company.
There are 6 different sub section in the technical services and those are as follows.
1. Aircraft Structure Section
2. Cabin Section
3. Electrical Section
4. Maintenance Planning Section
5. Power plant Section
6. Systems Section
Each section has their own ATA chapters which they have to look regularly. If there is an issue
in an aircraft, first refers the manuals and check whether the damage or defect is within the
limits. If it is not, the relevant section should analyze and suggest repair technique to the Airbus

31
company. Then OEM will provide a Repair Approval Design (RAD) Sheet or otherwise the
part should be replaced.
We have chance to access aircraft manuals in the SriLankan Airlines. Manuals are divided into
two sections as Technical Manuals and Organizational Manuals.
1 Technical Manuals – several manuals that are categorized under this section are
Aircraft Maintenance Manual, Illustrated Part Catalogue, Aircraft wiring manuals
etc.
2 Organizational Procedure Manuals – mainly there are 3 volumes
Volume 1 – general tasks carried out by the technical section system
Volume 2 – procedures and standards
Volume 3 – forms and tags
We have accessed to D-pub of the SriLankan Airlines and referred more details about the
sections.
2.2.2 Avionics Workshop
Avionics workshop has 7 sub workshops which have different capabilities in different
components. I have worked in the Avionics Workshop for 6 days (13th
of
September) and covered all the sub workshops. Those sub workshops are as follows.
2.2.2.1 Battery Workshop
Ni-Cd batteries are used currently in aircrafts. In the battery workshop, there are 3 types.
2758 type is used in A320 aircrafts and 4059 and 405CH type are used in A330 aircrafts. I have
assisted to charge, capacity check and battery overhaul in that section.
There are 3 types of charging methods as constant current method, rapid partial charge
and constant potential charge. In the charging process of 4059 type batteries, first removed the
battery cover and vent valves was adjusted as necessary. Then the battery was fitted to the
charger. This battery was charged under constant current method. The main charge is set to 31
V for 10 hours with 3.7 A. After that battery was charged for 4 hours with 3.7 A called over
charged. The monitoring process of the battery cells are done by taking down the cell voltages
for every hour. Electrolyte level was checked and then poured distilled water as mentioned in
the CMM.
After the fill charge time, each cell of the battery should have 1V or above. This check
is called as capacity check. If this check fails, individual cells are short circuited by using
alligator clips and fully discharged. That’s take about 14 hours.

32
I have assisted battery overhauling process in 4059 battery. First battery cover was
removed and then individual cells were removed with linkages, vent valves and liner spacer
kit. These battery cells outer was cleaned using water and battery box was cleaned using soapy
water. Also, linkages, nuts were cleaned with soapy water and brushed. After dried those
components, applied lubricant coating to the nuts and linkages.
In the assembly process, spacer kit, connectors were placed in the battery box. Then
battery cells were packed according to the numbered way as mentioned in the CMM. Finally,
spring washers, nuts and linkages were installed.
2.2.2.2 Electrical Workshop
In that workshop, I assisted to repair 3 Ballast units under the guidance of an approve
holder. Ballast unit is a light being fitted in the cabin area. There were several ballast units in
that section and those were removed in an C check of A330 aircraft.
In that process, first all the unites were cleaned using Isopropyl Alcohol. Then checked
each unit to identify the fault and inspect visually to identify cracks and dents in the cover.
There are three possible failures in a ballast unit. They are power loss, holder damage and
flickering.
Those three units were damaged cause of holder damage. So that, three holders were
ordered using Aura system. After that replaced those components and cleaned units again. Then
packed those and returned them to the stores with the completed documents.
2.2.2.3 Fuel & Waste Workshop
Here I have assisted to check the lavatories in an A330 aircraft and checked the
functionality using test machine.
Figure 2.10 Battery Short Circuit Diagram

33
2.2.2.4 Galley Workshop
In this workshop, repair and service coffee maker, steam ovens, chillers, beverage
makes etc. in the aircraft cabin compartment. I assisted with coffee maker, steam ovens
inspection and component replace under the guidance of an aircraft technician.
I tested a coffee maker using coffee maker tester. First the machine was mounted on
the particular coffee maker rail and heater was set to the machine. Then the readings of the
temperature were displayed in the display of tester. That machine, the required current was not
drawn. So that there was an issue in the relay component. That fault was identified by the
aircraft technician. Then replaced that relay and problem was solved.
A steam oven and a convection oven were tested using oven testing machine. In the
convection oven, minimum and maximum temperature ranges should be adjusted. In that
machine, there are two temperature ranges and those ranges should adjust as mentioned in the
CMM. So that the temperature ranges were adjusted using thermocouple adjustment and
observed the displayed temperature values. After few iterations, the temperature values were
set.
The stem oven there is no adjustment in the thermocouple because the temperature
values auto adjusted with a microcontroller. I had to check the temperature readings are within
the given limits. So, oven was connected to the test machine and tested the temperature readings
for 3 times. That machine worked correctly.
2.2.2.5 Oxygen Workshop
This workshop has capability to inspect, cleaning, charge and discharge processes in
crew oxygen bottles, portable oxygen bottlers. I have assisted to charge oxygen bottles under
the guidance of an aircraft technician.
Figure 2.11 Coffee Maker Tester

34
In the charging process first, the bottle was cleaned. The bottle should be free with
grease and hydrocarbons otherwise if they mixed with O2 will cause to burst. Then visually
inspect and ensure that there are no corrosions. If there were corrosions, the bottle should be
removed and send to repair.
After the inspection, the part number, series number and other details were recorded in
the document. Then cylinder was connected to the charging set up line and placed in the
charging cage. After that valve was open and set to charging position. The source O2 cylinders
were connected to the booster pump which was pneumatically operated to avoid electric sparks.
The bottles were charged up to 1850 psi as mentioned in the CMM and the pressure increment
was 50 psi per minute.
The purge technique [17] was used to fill the bottle, under the low O2 flow rate. This
method prevents mixing of environment air with O2. If air is mixed with O2, that will cause to
increase the moisture content inside the cylinder and in higher altitude that will cause to form
ice in the supply line. Also, that will cause to increase the corrosions inside the bottle.
2.2.2.6 Radio/ IFE Workshop
In this workshop I worked with emergency locator transmitter under the guidance of an
aircraft technician. I studied principle of the transmitter and servicing manual and the
maintenance process.
Also, assisted to repair and check the process of telephone head. Telephone head set is
used to get intercom function inside the aircraft between pilot, cabin crew as well as passengers.
The functionality was checked and there were no errors. So that complete set of the head set
was returned to the stored again.
Figure 2.12 Booster Pump

35
2.2.3 Composite/Paint Shop
I have assigned to the Composite/Paint Shop for 5 days (21st
of
September) This workshop has capability to repair several composites sections in aircrafts and
re-paint the damaged structures and paint removed components for inspections. In the
composite section, carbon fibre is the key material and several other materials are used relevant
to the components.
Paint workshop uses several methods to apply coatings to the components and remove
paint coatings. Chemical paint stripping of metallic structure by brush application and bath
method, paint removal by abrasion, repair damaged top coating, paint aluminum alloy
structures and composite structures, alloy structures etc. are several capabilities in the paint
workshop.
2.2.3.1 Materials in the Composite section
Basically, there are three composite structure types in the aviation industry as follows
1. Monolithic - available only carbon fibre or glass fibre
2. Sandwich Structure - honeycomb structures with glass fibre
3. Mixed structure - Both honeycomb and monolithic structures are used
Table 2.3 Materials used in Composite Section
Material Type Description
Honeycomb
HRH 10-3/16-6.0 (US)
ECA-4.8-96 (Metric)
Honeycomb Flexcore HRH10F50-5.0
Adhesive Film 120 ⁰C CYTEC/FIBERITE FM-73M.06
Glass Prepreg 120 ⁰C
HEXCEL 1454/50/7581
4H satin
Carbon Prepreg 120 ⁰C
HEXCEL/VICOTEX 913/46% G814NT
Plain weave
Dry Glass Fabric
91111
4H satin 105 g/m2
style 120
Dry Glass Fabric
91745
4H Satin 293 g/m2
Dry Carbon Fabric
AH 370-5H
5H Satin 370 g/m2

36
Dry Carbon Fabric
HEXCE G806
Plain weave 130 g/m2
Vacuum Bagging Film HCS 2101-04-60V
Breather Cloth HCS 2102-10
Non-Perforated Parting Film HCS 2108 NP
We have studied about different materials that are used in the composite section. The
material types and specifications are in the table 2.3.
These materials are used in different sections according to the characteristics and
properties. Carbon fibre, aramid fibre and glass fibre are often used materials in the aviation
field. In the Radom of the aircraft, quartz fibre are used because of the transparency to the radio
signals. Major disadvantages of the carbon fibre are cannot be recycled, strength in only one
direction and impact sensitive. But using composite structures, weight of the aircrafts can be
reduced. As an example, A350 aircraft manufactured using about 70% or above of composites
rather than metallic structures.
2.2.3.2 Vacuum bagging process
We did a practical about vacuum bagging using glass fibre and other relevant materials. First,
we cut the required size of the material and prepared to make bag. A layer of vacuum bag was
laid on the table and double-sided tape pasted along the edge without removing other next side
Figure 2.13 Layers of Materials Used

37
tape cover. Then measured resin and hardener into two separate cups as mentioned in the
instructions. Then mixed them up and prepared the adhesive.
The composite place that we prepared consists of 4 layers. Each layer was coated with the
adhesive and bonded together. After that it placed in the middle of the vacuum bag and over
that placed release fabric. Then placed non-perforated parting film and breather material
respectively (Figure 2.13). After that placed vacuum bag layer and using double sided tape,
made the vacuum bag. Then placed the port on the completed section and applied vacuum
pump for about 1hr (Figure 2.14).
After that removed the layers of the material and using filing, finished the composite plate that
we have prepared.
2.2.4 Wheels/Brakes Shop
This workshop has capability to cleaning, inspection, disassembling, assembling,
inflation of aircraft nose and main landing gears and brake units currently in A320, A321, A330
types aircrafts. I have assigned to this workshop for 10 days (1st
of October – 12th
of October)
and got hands-on experience.
2.2.4.1 Main Landing Gear Disassembly, and Assembly Process – A330
I was assisted to disassemble and assemble several aircraft tyres in the shop. Main
landing gear has two sections, inner half and outer half/ They were fitted together with 22 bolts
and 44 washers and centre packing. There are three sub-assemblies in the landing gear as outer
wheel half assembly, inner wheel half assembly and wheel and tire assembly. Landing gear
tyres are disassembled every 5 flying cycles and also after hard landings. There are several
other situations that cause to replace the tyres.
Figure 2.14 Vacuum Bagging

38
The tyre is deflated when it arrived to shop. In the disassembly part, first tyre and inner
and outer rings should be disbanded using Regent Bead Breaker machine. The height of the
two jaws in this machine was adjusted and then pressed from a side until the pop sound that
because After that tyre was insert into stand that use to hold the tyre without rolling. Then using
torque wrench and socket all the bolts and nuts were removed. These removed components
were stored in separate trays after numbering them.
The torque bars and heat shields in the outer half of the rim was removed with tyre
pressure indicating sensor and inflation valve. After that all of them were cleaned visually
inspected. If NDT inspection was required as mentioned in the CMM, they were hand over to
the NDT workshop.
In the assembling process of the aircraft tyres, new tyres were ordered from the stores.
Bolts, washers and nuts were coated with MOLYPAUL ZX 13 (S-720) graphite-based grease.
Torque bars and heat shields were installed in the outer rim of the landing gear.
Then using Universal Assembly Stand machine, tyre was fitted to the rim. The template
ring was fit to the machine and then bolts and washer was placed in that ring. Then inner half
of the ring was placed on the machine coincide with the template ring. After that pressure plate
was applied to the top and assembly stand was turned horizontally to get the tyre. Then tyre
was inserted to the rim and turned vertical again. After that outer half of the rim was placed on
the inner half and nuts were tightened in the pattern of Christ cross.
Then tyre was sent to apply bearing cups. Here applied AeroShell grease and installed
two bearing cups. In the final stage, tyre was rolled into the inflation cage and using Cryocart
(Mobile Pneumatic System) N2 was inflated until the required pressure mentioned in the CMM.
2.2.4.2 Main landing gear Carbon Brake Assembly and Testing – A321
The brake system was designed to operate through resistance friction between stator
and rotor disks. Pressure is applied through series of pistons which operates using hydraulic
pressure. There are two different hydraulic brake systems in a single tyre and so there are 14
pistons. There is a wear indicator pin that uses to measure weariness of the brake pads. There
are several sub-assemblies in the brake assembly.
In the adjuster assembly, first backup ring and performed packing rings were lubricated
and installed in the piston grave. Then scraper ring and was installed on the piston assembly
after applying hydraulic fluid. After that spring, spring guide and guide sleeve was installed
inside the piston. Then retainer ring was inserted to the second grove of the piston using arbor

39
pressing machine. Seal retainer, second retainer ring, pin retainer, piston, adjuster tube, self-
locking nut, instruction plate, new retainer ring and insulator assembly was fitted accordingly.
After all adjuster assemblies were prepared, they were torqued to the required level by
installing them in the adjuster assembly. Piston sleeve area was lubricated using hydraulic oil.
Then hydraulic fitting assembly and packings were installed in the piston housing. Carbon disk
assembly was fit to the piston assembly and completed the brake assembly [18].
Then testing process was conducted using hydraulic testing machine. Here 3000 psi
was applied to a hydraulic line and leaved about 3 minutes. After that make sure there are no
hydraulic leaks. Then hydraulic pressure was dropped to 0 psi. This test was conducted for
other hydraulic lines too,
2.2.5 Accessories Workshop
This workshop is capable of repair, modification and overhaul components such as
roller assembly of power drive unit (PDU), door latches, cargo loading systems and heat
exchangers etc. I have assigned to this workshop for 5 days (15th
of October – 22nd
of October).
This workshop has capability to maintain 103 components. Some of the components
are power drive units, different door latches, Spring rod, wiper arm, water faucet assembly,
drain valves, reheaters. I have assisted to disassembly, cleaning with Isopropyl alcohol, and
assembly of roller assembly in power drive units.
2.2.6 NDT Workshop
I have used 8 methods to detect cracks, dents, defects, etc. for different structural
materials and engineers are used them as mentioned in the AMM and CMM in the NDT
workshop under the guidance of engineers. I was there for 10 days (23rd
of October – 6th
of
November) and got hands on experience of operating machines and equipment. There are 8
different inspection methods used in that workshop. Some of them are same as we have worked
in the AEW. I have described other methods that I haven’t come across in the AEW.
2.2.6.1 Visual Inspection
Mirrors, magnifiers, borescopes and videoscopes are used under this method as I have
described in section 2.1.3.1.
2.2.6.2 Liquid Penetration Inspection
The same procedure was used in this method as we have practiced in AEW. The basic
process was described in section 2.1.3.2. I have assisted to inspect main landing gear outer rim

40
and inner rim of A320 and A330 aircraft wheels, Trent 700 engine mount bolts and piston
housings of A330 aircraft brake unit.
The chemicals that are used in this method are as follows.
1. ZL-67 – Water washable Fluorescent Penetrant (ZYGLO)
2. ZL-37 – Post Emulsifiable Fluorescent Penetrant (ZYGLO)
3. ZR-10E – Hydrophilic Emulsifier
4. ZL-27A – Post Emulsifiable Fluorescent Penetrant (ZYGLO)
5. SKC-S – Cleaner/Remover (SPOTCHECK)
6. SKL-SP2 – Penetrant (SPOTCHECK)
7. SKD-S2 – Developer (SPOTCHECK)
2.2.6.3 Magnetic Particle Inspection
Here used only magnetic bench method. The operating method is same as in the AEW
and described in section 2.1.3.3.1. Using this inspection method, I have assisted to inspect
bolts, nuts and torque bars of the aircraft landing gear.
2.2.6.4 Eddy Current Inspection
This method was used also in AEW NDT section and the details are in the section
2.1.3.4. I have assisted to do several inspections using this method as follows.
1. Outer wing trailing edge bottom skin after of rear spar above MLG reinforcing plate
2. Rotating probe testing

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