INTERNSHIP EXPERIENCE AT

ETHIOPIAN AIRLINES
AN INTERNSHIP REPORT BY:

Submitted By:

Kefiyalew Agegne (ID: ETS 0598/11)

Submitted in partial fulfillment of the Requirements for the award of

Degree of Bachelor of Science in Mechanical Engineering

SUBMITTED TO:
Department of Mechanical Engineering
ADDIS ABABA SCINCE AND TECHNOLGY UNIVERSITY
ADDIS ABABA

i
DECLARATION
I hereby declare that this internship report is an authentic record of my own works as
requirements of Industrial Training during the period from July 1, 2024 to september 30, 2024 G.C
for the award of degree of B.Sc. in Mechanical Engineering, Addis Ababa Science and Technology
University, Addis Ababa, under the guidance of (Mr. Komandar).

Name of Student: Kefiyalew Agegne

ID No: ETS 0598/11)

Date: 30/09/2024

i
Acknowledgement
Nothing can be accomplished alone. Without the help of the number of persons the success
Remains silent. I am very much fortunate to get the sincere guidance and supervision from a
number of people.
First and foremost I express our thankfulness to god for his blessing and guidance throughout
our entire training , I would like to extend our sincerely thanks to Dr. Melaka Department head
of Mechanical Engineering for allowing us to carry out this internship program . I would also
like to extend my sincere and gratitude to Mr.Komander who helped us to be accepted by
Ethiopian Airlines .he always guide, give direction us throughout our internship training.
Moreover, I would like to thank Mr. Erma’s (Mechanical team leader), who always guide me and
my team mates. He is very kind and willing to help in every aspect. We are grateful to our intern
advisor Dewitt (Dry), for his comments and suggestions for those whole hearted supervision
during company attachment period. It would have been very difficult to prepare this report up to
this mark without their guidance finally, we thank all our partners and who supports us for their
endless love, encouragement and understanding they had shown during the whole time.

ii
Contents
DECLARATION ..................................................................................................................................... i
Acknowledgement ................................................................................................................................... ii
Table of figure......................................................................................................................................... v
ACRONYMS ......................................................................................................................................... vi
Chapter one ............................................................................................................................................. 1
Introduction ......................................................................................................................................... 1
1.1 Background/profile of Ethiopian airlines ........................................................................................ 1
1.2 COMPANY’S VISION, MISSION ................................................................................................ 2
1.2.1 Company’s vision ................................................................................................................... 2
1.2.2 Mission ................................................................................................................................... 2
1.2.3 Services of the Organization .................................................................................................... 2
1.3 Structural organization of main activity .......................................................................................... 3
................................................................................................................................................................ 3
............................................................................................................................................................ 3
Figure 1 ................................................................................................................................................... 4
Figure 2. .................................................................................................................................................. 5
Chapter two ............................................................................................................................................. 5
Detail of Working Experience ................................................................................................................. 5
2.1. Summary of Duties ....................................................................................................................... 5
2.1.2 Major Duty I Were Given to Perform ...................................................................................... 5
2.1.3 How Did I Become Oriented With the Responsibilities You Were Assigned? .......................... 6
2.1.4 Specific job information .......................................................................................................... 6
1. Preparation and Safety Measures ................................................................................................ 18
GENERAL REPAIR INSTRUCTIONS ......................................................................................... 18
5. Replacement of Worn Parts ........................................................................................................ 23
5. Replacement of Worn Parts ........................................................................................................ 23
6. Reassembly of the Engine .......................................................................................................... 24
7. Engine Timing and Valve Adjustment ........................................................................................ 24
8. Fluids Refill ............................................................................................................................... 24

iii
 9. Battery Reconnection ................................................................................................................. 24
10. Final Testing ............................................................................................................................ 25
2.1.4.9 Transmission and their types .............................................................................................. 25
2.2 working experience.......................................................................................................................... 32
2.2.2 CHALLENGES IN ETHIOPIAN AIRLINES ........................................................................ 33
Measures taken to overcome the challenges ........................................................................................... 33
2.3 Learning outcomes ....................................................................................................................... 33
2.3.1 THE BENEFITS WE GAINED FROM INTERNSHIP .......................................................... 33
2.4. Applications of Theory and Soft Skills ........................................................................................ 34
2.4.1 How Did Your Supervisor Help You to Succeed in the Assignment You Were Given? .......... 34
2.4.2 What Qualities Did I Develop Which Allowed me to Succeed in my Daily Duties? ............... 34
Chapter Three........................................................................................................................................ 36
Conclusion and Recommendation ...................................................................................................... 36
3.1 Conclusion................................................................................................................................... 36
3.2 Recommendation ......................................................................................................................... 36
Reference .............................................................................................................................................. 37

iv
Table of figure
Figure 1 Structural organization of main activity .........................................................................3
Figure 2 Flow chart of preventative maintenance ........................................................................4
Figure 3 TANK ...........................................................................................................................8
Figure 4 WORKSHOPE ............................................................................................................ 18
Figure 5 TRANSMISSION COMPONENTS ............................................................................ 26
Figure 6 plate clutch disassembled ............................................................................................ 31

v
ACRONYMS

TWA Trans World Airlines

DC-3 Douglas Commercial 3

MRO Maintenance Repair and Overhaul

ACE Achieving Competitive Excellency

TPM Total Preventive Maintenance

MFA Market Feedback analysis

EAL Ethiopian Airlines

AC Air conditioner

EXV Electronic expansion valve

vi
Chapter one
Introduction
1.1 Background/profile of Ethiopian airlines
Ethiopian airline is a commercial enterprise that provides scheduled flights for passengers. This
Ethiopian airline which is found at Bole international Airport is consisting of three sections such
as Airline line, Airport and Civil Aviation. Airline is a company that flies airplane to transport
people and goods, Airport is an airfield equipped with control tower and hangars as well as
accommodations for passengers and cargo and civil aviation is one of major categories of flying
representing all nonmilitary aviation both private and commercial.

The Bole International Airport Is Located at Ethiopian Capital City Which Is Capital City of Addis
Ababa. The state-of-the-art maintenance hangar with a span of 7,200 square meters and a height
of 25 meters can accommodate one B747-400 or two B737-700s or two equivalent size aircraft at
any given time in different configuration. Ethiopian has an advanced maintenance base, which is
fully operational for Airframe maintenance up to D-Checks, Engine, Overhaul, Components repair
& overhaul, Light Aircraft maintenance and technical, and management assistance for other
airlines.
Ethiopian Airlines (Ethiopian) is the flag carrier of Ethiopia. During the past years, Ethiopian has
become one of the continent’s leading carriers, unrivalled in Africa for efficiency and operational
success, turning profits for almost all the years of its existence. Operating at the forefront of
technology, the airline has also become one of Ethiopia’s major industries and a veritable
institution in Africa. It commands a lion’s share of the pan African network including the daily
and double daily east-west flight across the continent. Ethiopian currently serves 69 international
destinations operating the newest and youngest fleets.
Ethiopian Airlines, formerly Ethiopian Air Lines Inc. (EAL), was created by the decree of Emperor
Haile Selassie I at the end of 1945.

1
The first scheduled flight took place to Cairo via Asmara in Douglas C-47 Sky train. The national
airline had been set up a few months earlier as Ethiopian Air Lines Inc., a joint venture with
American airline, TWA (Trans World Airlines).

As of the latest available data, Ethiopian Airlines employs around 17,000 to 18,000 people in total.
This workforce spans various sectors, including flight operations, cabin crew, ground services,
engineering, and administration.in facility maintenance 28 employees, in total estimated up to
more than 3000 mechanical engineers

1.2 COMPANY’S VISION, MISSION

1.2.1 Company’s vision
Ethiopian will be the most competitive and leading aviation group in Africa by providing safe,
market driven and customer focused passenger and Cargo Transport, Aviation Training, Flight
Catering, Maintenance Repair and Overhaul (MRO), Ground Services, Domestic and regional
services by 2025.
1.2.2 Mission
 To become the leading Aviation Group in Africa by providing safe and reliable passenger

and cargo transport, aviation training, flight catering, MRO and ground services whose
quality and price “value proposition” is always better than its competitors
 To ensure being an airline of choice to its customers, employer of choice to its employees and
an investment of choice to its owner
 To contribute positively to the socio-economic development of Ethiopia in particular and the
countries it operates in general by undertaking its corporate social responsibilities and
providing vital global air connectivity
1.2.3 Services of the Organization
The airport offers a variety of services, including aircraft maintenance, ground handling, cargo
services, and passenger services. The laundry department handles cleaning services for uniforms
and other fabrics used in the airport, while the automotive department is responsible for
maintaining the airport’s fleet of vehicles, including tugs, fuel trucks, and other essential
equipment.

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1.3 Structural organization of main activity

Board of Management
f

Chief Executive Officer

Vice president Vice president

Internal Audit and Compliance
Legal Counsel and Corporate
Director Secretarial
CEO Office

Chief Operating Chief Commercial Chief Financial SVP VP

Officer Officer Officer
Corporate HRM Aviation Academy
ce
SVP SVP VP Dir, Change & Director, AMTS
performance and PTS
Ethiopian MRO Global Sales Corporate Finance management

VP Dir, Personnel
VP Chief Dir, Commercial
Flight Operations Administration Services and
Marketing Information Leadership
VP Officer Dir, Human
Training

Resources Dev’t
Customer Services
VP Alliance &
VP Dir, Medical Unit Corporate Strategy
& Health Services Planning
Ethiopian Cargo
Director Dir, corporate
security
Domestic Sales &
Services

3
 Figure 1

Flow chart of preventative maintenance

Preparation correction
Open work In
SAP
Is the
mechine
ready
Configure
Work order in
SAP
Figure 1 Flow chart of preventative
maintenance
File and per
schedule doing

Assign
technician 3
min

Material Work
started costumer
change if
necessary Inform to
customer

To machine

Cc compare work
Tools
order and
SA manual
preparation
SAP 5 min

The necessary
job will

4
Started prelist

Figure 2.

Chapter two

Detail of Working Experience

2.1. Summary of Duties
2.1.2 Major Duty I Were Given to Perform

During my internship at Ethiopian Bole International Airport, I was given a range of duties in both
the facility maintenance and automotive departments. In the first month, my major duty was to
assist in the maintenance of laundry machines, particularly focusing on the dry cleaning machine
and its various components, such as the AC unit, pump, and sensors. I was responsible for regularly
checking these components to ensure they were functioning properly, as well as performing routine
maintenance tasks like cleaning the evaporator coil and checking the levels of refrigerant gas in
the AC system.

In the second and third months, I was assigned to the automotive department, where my primary
responsibility was the maintenance and repair of the airport’s fleet of vehicles. My duties included
servicing tires and brakes, checking the radiator and battery, and performing more complex tasks
like disassembling and maintaining tug engines and transmissions. These responsibilities were
crucial to ensuring that the vehicles used for transporting luggage, fuel, and aircraft operated safely
and efficiently.

One specific task that stood out was the disassembly, maintenance, and reassembly of a tug engine.
This duty required precision and technical knowledge, as the engine is a vital component of the
tug, which is used to move aircraft on the ground. Additionally, I was involved in the maintenance
of air conditioning systems, where I checked components such as the compressor, condenser, and
evaporator to ensure proper cooling. My work in the automotive shop also included conducting
5
preventative maintenance for the vehicles used in airport operations, ensuring that they were in
optimal condition for day-to-day use.

2.1.3 How Did I Become Oriented With the Responsibilities You Were Assigned?

I became oriented with my responsibilities through a combination of formal orientation sessions

and hands-on guidance from my supervisors. On the first day, Mr. Kokand and the team leaders
gave me and my teammates an overview of the tasks we would be performing in both the laundry
and automotive departments. This orientation included a tour of the facilities, during which we
were introduced to the machines and equipment we would be working with, as well as the safety
procedures that were essential for handling them safely and effectively.

In the laundry department, I was initially guided through the processes involved in maintaining
the dry cleaning machines and boilers. The team leaders explained the functions of each
component, such as the AC unit and pump, and demonstrated the proper way to clean and maintain
them. As I progressed, I became more confident in handling these tasks on my own.

Similarly, in the automotive shop, I received training on how to service various vehicle
components. My supervisors showed me how to disassemble and reassemble engines, and service
brakes. They also provided detailed explanations of how the transmissions and other mechanical
systems operated, which helped me understand the practical applications of the knowledge I had
gained in my coursework. This combination of theoretical and practical training helped me quickly
adapt to the responsibilities I was assigned.

2.1.4 Specific job information

First Month, Laundry Shop
2.1.4.1 Orientation by Mr. Kokandar and Team Leaders
In the first few days, we were given an orientation by Mr. Kokand and the team leaders.
Orientation is crucial for understanding how the shop operates and the roles we would play. We
were introduced to safety procedures and instructed on how to use various machines. This
orientation helped me familiarize myself with the workflow and rules, which were essential for
preventing accidents and ensuring smooth operations.

6
2.1.4.2, Laundry Shop Assigned to
After the orientation, I was assigned to work in the laundry shop along with my teammates. Our
main tasks were to maintain the industrial machines that keep the shop running, including dry
cleaning machines and boilers. These machines are vital for ensuring that uniforms and other
fabrics are cleaned effectively. Working in this department was challenging at first, but I quickly
learned how to operate the machines safely and efficiently.

2.1.4.3 Description of the Laundry Shop and Machines

The laundry shop consists of several machines, including boilers and dry cleaning machines. The
boiler heats water to generate steam, which is used for cleaning fabrics. The dry cleaning machine
uses a chemical solvent, typically perchloroethylene, to clean clothes without water. These
machines are large and complex, requiring regular maintenance to prevent breakdowns.

2.1.4.4 Dry cleaning

Dry cleaning is any cleaning process for clothing and textiles using a chemical solvent other
than water. I t i s u s e d to clean fabrics that degrade in water, and delicate fabrics that cannot
withstand the rough and tumble of a washing machine and clothes dryer. I t can
e l i m i n a t e labor-intensive hand washing. Unlike what its name implies, dry cleaning is not act-ally
a 'dry' process. Clothes are soaked in a different solvent other than water. The solvent
used is t ypically toxic tetrachloroethylene (perchloroethylene), which the industry calls “perc
The work tank contains solvent, which is used over and over.

The solvent is pumped from the work tank to the cage.

If there is not enough solvent in the work tank, fresh solvent is taken from the clean tank.

After the garments have been cleaned, the solvent is pumped back to the work tank or to the
distillation.

Tank 3 is an extra tank for special applications. If an optional second centrifuge filter is used, this
is allocated to the third tank. This permits separate cleaning of light and dark products.

The clean tank holds clean solvent that has been recovered from the distillation and drying. When
the clean tank overflows, it fills up the work tank again. Sacrificial anodes in the tanks protect
against corrosion.

7
Figure 2 TANK

Button Trap

The button trap strainer (1) catches large impurities (such as buttons, etc.) and lint in the detergent
solution. Never operate the system without the button trap strainer. (Risk of damaging the solvent
pump). During the drying, a flow of air dries the dirty lint in the button trap strainer.

Lint filter
The lint filter (3) catches the lint that is carried along in the air flow. The lint filter is in the button
trap housing. Never operate the system without the lint filter. Never use a damaged lint filter. Make
sure that the lint filter sits firmly in place. (Risk of lint on the cooling register)

Loading Door Venting

When the loading door is opened, the machine fan starts to run the machine. This fan prevents air
containing solvent from entering the area around the machine operator during loading and
unloading of the machine. The cage is ventilated until the loading door is closed.

Distillation

What to Do If the Machine Malfunctions

8
 1. 2. 3. If there is an error, the machine stops and displays the error.
2. You can identify the error with the diagnosis list (or on the display). 8.3
3. After you have corrected the error, delete the error message with C and press the START
button to restart the machine.

2.1.4.6 Operation and Maintenance Summary

When starting operation:

 Turn on steam supply

 Turn on room ventilation system
 Turn on cooling water supply
 Turn on compressed air supply Open condensate valve
 Turn on machine main switch Start deodorizing program P43, press "STOP" button
when program ends and signal sounds

When stopping operation:

 Turn off machine main switch

 Turn off steam supply Close condensate valve
 Turn off cooling water supply
 Turn off compressed air supply cooling compressor
 Turn off room ventilation system or switch to night operation

Inspection and maintenance work:

Daily:
(Before starting the first cycle) Check machine for leaks
Check solvent safety trough for solvent if necessary, add neutralization agent to still clean
button trap strainer and lint filter)
Check safety separator, if necessary, dispose of process water in accordance with the
regulations that apply in your country Check the liquid level of the cleaning agent
container Machine is ready for operation Daily:
Semi-annually:
Check, clean air cooler clean tanks Retighten screwed unions Check V-belt tension, re-
tension Replace carbon in venting and aeration filters

9
 Annually:
Machine inspection (according to BGR 500 chapter 2.14) Remove filter discs and clean in
the machine

Maintenance

Distillation Maintenance

The most important factor in solvent inspection and care is the use of high-quality perc and suitable
chemical additives.

The dry-cleaning detergent, in particular, should contain solvent stabilizing components.

The pH value is an important indicator for the quality of the solvent. In a well-run operation, the
value should be determined once a month as a matter of course.

Solvent care is an essential factor in the reliability and long-life of the machine and in the quality
of the cleaning that the garments receive. It includes routine maintenance of the still and water
separator and the use of quality products.

AC unit maintenance

Troubleshooting

SAFETY PRECAUTIONS FOR DRY CLEANER

If ANY of the following conditions occurs,

 Turn off your unit immediately!
• The power cord is damaged or abnormally warm
• You smell a burning odor
• The unit emits loud or abnormal sounds
• A power fuse blows or the circuit breaker frequently trips
• Water or other objects fall into or out of the unit

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Problem Possible cause Solution

Power failure Wait for the power to be restored

The power is turned off Turn on the power

The unit starts and

stops frequently There’s too much or too little system Check for leaks and
refrigerant in the recharge the system with
refrigerant

Incompressible gas or moisture system Evacuate and recharge the

has entered the system with refrigerant

The compressor is broken Replace the compressor

The voltage is too high or too low Install a man stat to regulate the
voltage

Poor heating
performance The outdoor temperature is Use auxiliary heating device
extremely low

Cold air is entering through doors Make sure that all doors and
and windows windows are closed during use

Low refrigerant due to leak or Check for leaks, re-seal if

long-term use necessary and top off refrigerant

11
Table 1

Why ice formed in our compressor

Here are the main reasons why ice may form on your AC unit:

Restricted air flow

Equate airflow is essential for the air conditioner to function correctly, when air filters become
clogged with dust, per hair, or other debris, or the air ducts are obstructed, airflow is reduced. This
causes the coils to get too cold and freeze the moisture in the air, forming ice.

To address restricted airflow, chech and replace the air filter if it’s dirty or clogged.

Refrigerant is the lifeblood of your air conditioning system, absorbing heat from indoor air and
releasing it outside. If the refrigerant level drops due to leaks or other problems, the pressure and
temperature inside the system fall, forming ice on the coils.

Faulty components

A malfunctioning blower motor or a damaged thermostat might cause icing. Issues with these
systems lead to temperature imbalances and ice buildup.

To troubleshoot, turn off your air conditioner and visually inspect the damage. If you notice any
issues unusual noises or erratic cycles contact a professional HVAC technician for diagnosis and
repair.

Steps to fix
Ice formation on your air conditioner reduces cooling efficiency and can damage your unit.
Act quickly to mitigate damage and avoid major repairs or replacing your air conditioner
early.
1. turn off air conditioner
If you notice ice formation on your AC, the first step is immediately turning off the unit.
Continuing to run the air conditioner with ice buildup can damage the compressor and fans.
Allow the ice to melt completely before trying any troubleshooting tips

12
 2, cheek and replace the air filter
Inspect the air filter and replace it if it's dirty or clogged. Replace the air filter every one to
three months to maintain optimal airflow and reduce airborne particles.
3, inspect the air vents and coils

Ensure your air vents are open and unobstructed. Then, inspect the evaporator and
condenser coils for any dirt or debris. Clean the coils to improve heat transfer and prevent
ice formation.
4, consider system upgrade
If your air conditioner is old or inefficient, consider upgrading to a newer, more energy-
efficient model. Modern AC systems are designed to minimize ice formation and improve
overall performance, saving you money on energy bills in the long run.
Cause of compressor over heating
1, damage or dirty air filter
Damaged or dirty air filters restrict the airflow around the unit, causing the warm air to get
trapped inside. The air conditioner would have trouble getting air through a dirty or
damaged air filter as well, which forces the unit to work harder. These can cause the
compressor to overheat as it works harder to circulate refrigerant with the restricted airflow.

2, high head pressure

Similarly, dirty condenser coils in the air conditioners outside unit may get clogged as dirt
and debris pile up through the vents. Dirty coils because high head pressure, which may
make your compressor overheat as the cooling system fails to let the warm air out of the
unit.
The most common reason for high pressure is a dirty coil.

3, low refrigerant level

When there's not enough coolant for the compressor to circulate, it can start to grind the AC system,
which causes the mechanisms to overheat. Low refrigerant levels usually lead to serious problems,
like leaking water, frozen AC coils, and even burnt smells. That burnt smell is the compressor
overheating. Low refrigerant charge is often caused by a leak in the refrigerant pipes.

13
4, inadequate air conditioner size

An air conditioner that is too small or weak to cool the room to the desired temperature
will force the system to work harder to achieve the temperature set on the thermostat. This
causes an overheating compressor.

Solution
1, clean the air filter and evaporator coil
2, clean the condenser coil and remove heat source
Steam boiler preventative maintenance

4. Maintenance of the Dry Cleaning Machine

The dry cleaning machine has several important components: the air conditioning (AC) unit,
pump, diesel engine, sensors, drum, and water lines. My responsibility was to check each
component regularly to ensure it was functioning properly. Maintenance of the AC unit was
particularly important because overheating could cause the machine to fail. We also had to check
the drum for any issues with chemical buildup or mechanical wear.

5. Checking Evaporator Coil for Dust

The evaporator coil in the AC unit absorbs heat and helps to cool the machine. If dust
accumulates on the coil, it can reduce the efficiency of the AC unit. My task was to clean the coil
regularly to ensure proper cooling. This was a straightforward task but essential for keeping the
machine running smoothly.

Condenser, Evaporator, Valve6. Checking AC Unit (Compressor, Expansion)

The AC unit in the laundry shop has several key components: the compressor, condenser,
evaporator, and expansion valve. Each component plays a crucial role in the cooling process. I
checked the compressor for signs of overheating and ensured that the condenser was not clogged.
The expansion valve regulates the flow of refrigerant, so it was important to check for any
blockages.

7. Checking and Maintenance of Condenser and Expansion Valve

14
 The condenser removes heat from the AC system, while the expansion valve controls the amount
of refrigerant that enters the evaporator. Any malfunction in these components can lead to
inefficient cooling or even system failure. Regular maintenance involved checking for leaks,
cleaning the condenser coils, and replacing any faulty parts.

8. Maintenance of Pump

The pump in the dry cleaning machine circulates the solvent through the system. A
malfunctioning pump could cause the machine to stop working. I was tasked with inspecting the
pump for any signs of wear and tear, as well as replacing any damaged parts. Proper maintenance
of the pump is crucial to the operation of the dry cleaning machine.

Copper Welding for Cracked Materials

Copper welding is a process used to join or repair copper components that may be damaged or
cracked. During my internship, I was involved in welding cracked copper pipes, primarily in the
air conditioning (AC) units. The purpose of welding is to ensure that the pipe or material can hold
pressure and maintain its structural integrity. This is especially important in the AC system because
any cracks or leaks could result in a loss of refrigerant gas or improper cooling, which could
severely affect the unit’s performance.

For copper welding, we used the oxyacetylene welding process. Oxyacetylene welding involves
using a torch that mixes oxygen and acetylene gas to produce a flame hot enough to melt copper.
The melted copper is then fused, forming a strong bond that repairs the crack. Before starting, I
had to ensure that all safety precautions were followed, such as wearing protective gear, ensuring
the gas connections were secure, and working in a well-ventilated area.

One of the most important aspects of copper welding is cleaning the surface before welding. The
copper must be free from dirt, grease, or oxidation to ensure a good weld. After welding, we
performed tests to ensure the weld was strong enough to withstand the pressure in the AC unit.

Testing Pressure in AC Unit

After completing repairs like welding, it’s essential to test the pressure in the AC unit to ensure
everything is working correctly. AC units operate under pressure, and if there is a leak or

15
insufficient pressure, the cooling system will not function as expected. The pressure testing process
involves filling the unit with nitrogen gas, which is a safe, non-reactive gas. By filling the AC unit
with nitrogen, we can check if there are any leaks in the system by monitoring the pressure level.

During pressure testing, the pressure gauge is used to track the readings. If the pressure drops over
time, it indicates that there is a leak somewhere in the system. If the pressure remains stable, the
system is sealed, and the unit is ready for refrigerant gas to be added.

Checking and Maintenance of Boiler

BOILER MAINTENANCE

Here are three crucial reasons to implement a PM program:

1. maintain water quality

2. ensure proper boiler blow down
3. facilitate appropriate insulation

The boiler in the laundry shop plays a vital role in providing steam for cleaning processes. Regular
maintenance of the boiler is essential to ensure it operates safely and efficiently. The tasks involved
in checking and maintaining the boiler included:

Description of air compressor

An air compressor is a machine that converts power into potential energy stored in pressurized air.
This equipment is vital in various applications, including powering pneumatic tools, filling tires,
and in the case of my internship, assisting with cleaning and operating certain tools in the
automotive shop.

The air compressor works by taking in air and compressing it to a higher pressure. The compressed
air can then be stored in a tank and used when needed. During my internship, I learned about the
different components of an air compressor, such as the motor, pressure switch, valves, and storage
tank. Understanding how these components work together was key to performing effective
maintenance.

16
Preventative maintenance of air compressor for simulation class

Preventative maintenance of the air compressor is essential to extend its life and ensure it functions
correctly during critical tasks. The tasks I performed included checking the oil levels, cleaning air
filters, inspecting hoses for leaks, and draining moisture from the tank to prevent rust. For the
plane simulation class, the air compressor was used to simulate aircraft systems, so ensuring it
worked properly was crucial for accurate simulations.

By performing regular maintenance, such as lubricating moving parts and replacing worn
components, we could avoid unexpected failures and ensure that the air compressor was
always ready for use in training and simulation exercises

Second and Third Months

2.1.4.7 Assigned to Automotive Shop
In the second and third months of my internship, I was assigned to the automotive shop. This
department is responsible for maintaining the airport’s fleet of vehicles, including tugs, fuel trucks,
and other essential equipment. My tasks ranged from basic vehicle maintenance, , to more complex
repairs, such as engine disassembly and transmission service.

 Engine overhaul, in this section we have seen different parts and components
of engine as well as both type of transmission in power train, engine overhaul,
injector nozzle repair and calibrating and injection pump overhaul

17
Figure 3 WORKSHOPE

2.1.4.8 Tug engine service

1. Preparation and Safety Measures

 Step 1: Gather tools and equipment – Ensure you have all necessary tools like wrenches,
screwdrivers, oil filters, new gaskets, and lubricants.
 Step 2: Wear safety gear – Put on protective gloves, goggles, and work boots to ensure
safety during the service.
 Step 3: Disconnect the battery – To prevent electrical hazards, disconnect the battery before
starting any work on the engine.
 Step 4: Drain fluids – Drain the engine oil and coolant by opening the drain plugs. This
prevents any spills during the service process.

GENERAL REPAIR INSTRUCTIONS

1. Use fender, seat and floor covers to keep the vehicle clean and prevent damage.
During disassembly, keep parts in order to facilitate reassembly. Observe the following:

Before performing electrical work, disconnect the negative (-) cable from the battery terminal.

A. If it is necessary to disconnect the battery for inspection or repair, always disconnect the
cable from the negative (-) terminal which is grounded to the vehicle body.

18
 B. To prevent damage to the battery terminal post, loosen the terminal nut and raise the cable
straight up without twisting or prying it.
C. Clean the battery terminal posts and cable terminals with a shop rag. Do not scrape them
with a file or other abrasive object.
D. Install the cable terminal to the battery post with the nut loose, and tighten the nut after
installation. Do not use a hammer to tap the terminal onto the post.
E. Be sure the cover for the positive ( + ) terminal is properly in place. Check hose and wiring
connectors to make sure that they are secure and correct.
Non-reusable parts
(a) Always replace cotter pins gaskets, O-rings, oil seals, etc. with new ones.
(b) Non-reusable parts are indicated in the component illustrations by the
TROUBLESHOOTING
Diesel Engine Diagnosis
 Diesel engine problems are usually caused by the engine or fuel system.
 The injection pump is very rarely the cause of fuel system problems.
 Before beginning fuel system tests, first check that the engine compression,
valve timing and other major systems are within specifications.
PRELIMINARY CHECKS
1. Before performing fuel system checks, ensure that the engine is in good running condition.
2. If necessary, first check the compression, timing and major components or systems.
3. Check the air filter, and clean or replace it if necessary.
4. Check that there is sufficient fuel in the tank.
5. Check if the fuel is contaminated with gasoline or other foreign elements.
6. Only good-quality diesel fuel should be used.
7. Bleed air from the system by pumping the priming.
8. Check for water in the fuel filter and fuel tank, and drain as necessary.
9. If the engine will not crank or if it cranks slowly, first troubleshoot the electrical system

REMOVAL OF CYLINDER HEAD

. Drain engine coolant

. Remove intake pipe

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. Remove injection pipes
. Remove oil dipstick and oil dipstick guide
. Remove intake manifold
. Remove water outlet
. Remove nozzle leakage pipe
. Remove injection nozzles
. Remove glow plugs
. Remove exhaust manifold
. Remove turbocharger and exhaust manifold assembly
. Separate exhaust manifold
Disassembly of cylinder head
. Remove valve lifters
. Remove valves
. Remove combustion chambers
. Remove half circular plug

Inspection, cleaning and repair of cylinder head components

.clean top of pistons and top of block
. Remove gasket material
. Clean combustion chambers
. Clean valve guide bushings
. Clean cylinder head
. Inspect cylinder head for flatness
. Inspect cylinder head for cracks
. Clean valves
. Inspect valve stems and guide bushings
. If necessary, replace valve guide bushings
. Inspect and grind valves
. Inspect and clean valve seats
. Inspect valve springs
. Inspect camshafts and bearing

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. Inspect intake and exhaust manifolds
Installation of cylinder head
. Select new cylinder head gasket
. Install cylinder head
.install camshaft
. Adjust valve clearance (valve clearance (cold):
Intake 0.15-0.25 mm (0.006-0.010 in.)
exhaust 0.35-0.45 mm (0.014-0.018 in.)
Disassembly of cylinder head
. Remove valve lifters
. Remove valves
. Remove combustion chambers
. Remove half circular plug

Inspection, cleaning and repair of cylinder head components

.clean top of pistons and top of block
. Remove gasket material
. Clean combustion chambers
. Clean valve guide bushings
. Clean cylinder head
. Inspect cylinder head for flatness
. Inspect cylinder head for cracks
. Clean valves
. Inspect valve stems and guide bushings
. If necessary, replace valve guide bushings
. Inspect and grind valves
. Inspect and clean valve seats
. Inspect valve springs
. Inspect camshafts and bearing
. Inspect intake and exhaust manifolds
. Installation of cylinder head

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 . Select new cylinder head gasket
. Install cylinder head
.install camshaft
. Adjust valve clearance (valve clearance (cold):
Intake 0.15-0.25 mm (0.006-0.010 in.)
exhaust 0.35-0.45 mm (0.014-0.018 in.)

Post assembly

Install engine mounting

1. install thermostat and water inlet

2. Install oil cooler
3. Installtiming gear case (oil pump) and oil pan
4. Install injection pump)
5. install timing gears
6. Install alternator install water pump (see page co-8)
7. Install cylinder head
8. Install pulleys and timing.
9. Remove engine stand

INSTALL FLYWHEE

2. Engine Inspection
Step 1: Visual check – Inspect the engine for any visible signs of damage, such as leaks,
corrosion, or worn-out components.
Step 2: Inspect belts and hoses – Check for cracks or wear on belts and hoses. Replace if
necessary.
Step 3: Check the air filter – Remove and inspect the air filter. If it is clogged or dirty, replace it
with a new one.
3. Disassembly of the Engine

 Step 1: Remove external components – Start by removing the alternator, exhaust manifold,
and intake manifold to gain access to the engine.

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  Step 2: Remove the cylinder head – Carefully unbolt the cylinder head to inspect the
internal components, including the valves and piston.
 Step 3: Remove the pistons – Detach the pistons from the connecting rods and inspect them
for wear or damage.
 Step 4: Inspect the crankshaft – After removing the pistons, check the crankshaft for any
signs of wear or scoring.

4. Cleaning and Inspection of Parts

 Step 1: Clean the engine block – Use a degreaser to clean the engine block and remove any
buildup of grime or oil.
 Step 2: Inspect the cylinder walls – Check the cylinder walls for scoring or damage. If
necessary, use a honing tool to smooth out the walls.
 Step 3: Clean the pistons and valves – Remove carbon deposits from the pistons and valves.
Use a wire brush or cleaning solvent to ensure they are free of debris.
 Step 4: Check for leaks – Inspect the gaskets and seals. Replace any gaskets that are
damaged or worn out.

5. Replacement of Worn Parts

 Step 1: Replace pistons and piston rings – If the pistons or rings are damaged or excessively
worn, replace them with new parts.
 Step 2: Install new gaskets – Replace the cylinder head gasket, valve cover gasket, and any
other seals to prevent leaks when the engine is reassembled.
 Step 3: Replace filters – Install a new oil filter and fuel filter to ensure the engine runs
clean.

5. Replacement of Worn Parts

 Step 1: Replace pistons and piston rings – If the pistons or rings are damaged or excessively
worn, replace them with new parts.
 Step 2: Install new gaskets – Replace the cylinder head gasket, valve cover gasket, and any
other seals to prevent leaks when the engine is reassembled.

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  Step 3: Replace filters – Install a new oil filter and fuel filter to ensure the engine runs
clean.

6. Reassembly of the Engine

 Step 1: Reinstall the pistons – Reattach the pistons to the connecting rods and insert them
back into the cylinder block.
 Step 2: Reinstall the cylinder head – Secure the cylinder head in place and ensure that all
bolts are torqued to the manufacturer’s specifications.
 Step 3: Reassemble external components – Reattach the intake manifold, exhaust manifold,
and any other external components removed earlier.

7. Engine Timing and Valve Adjustment

 Step 1: Set the engine timing – Align the timing marks on the crankshaft and camshaft to
ensure the valves open and close at the correct time.
 Step 2: Adjust the valves – Use a feeler gauge to check the valve clearance and adjust the
intake and exhaust valves as needed to match the manufacturer’s specifications.

8. Fluids Refill

 Step 1: Refill engine oil – Pour in new engine oil according to the engine’s specifications.
 Step 2: Refill coolant – Add coolant to the radiator, ensuring the system is properly filled.
 Step 3: Check and top off other fluids – Check power steering fluid, brake fluid, and
transmission fluid levels, topping them off if necessary.

9. Battery Reconnection

 Step 1: Reconnect the battery – After completing the reassembly, reconnect the battery
terminals.

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10. Final Testing

 Step 1: Start the engine – Turn on the engine and listen for any unusual sounds, such as
knocking or rattling.
 Step 2: Check for leaks – Inspect the engine for any signs of oil, fuel, or coolant leaks.
 Step 3: Monitor engine performance – Let the engine run for a few minutes and check the
temperature gauge, oil pressure, and RPM levels.
 Step 4: Test drive – If everything looks and sounds good, take the tug for a test drive to
ensure it operates smoothly and that the engine is working properly.

Radiator service

The radiator cools the engine by circulating coolant.

. Main Parts: Radiator core, coolant hoses, radiator cap, thermostat.

. Troubleshooting: Look for coolant leaks, overheating, or low coolant levels.
. Main Problems: Leaking hoses, clogged radiator, low coolant.
. Solution: Replace leaking hoses, flush the radiator, and refill coolant.
. Maintenance Steps:

1. Check coolant level.

2. Inspect hoses for leaks or damage.
3. Clean or replace the radiator if clogged.

2.1.4.9 Transmission and their types

Transmission is a mechanical system that transmits the torque from the engine to the driving
wheels and also a gear box is needed to enable the engine to cope with wide variations in the
power and torque required to drive the care under such different conditions. In effect, the faster
the crank shaft revolves in relation to the rode wheels, the greater is the force available to drive
the car; buy the speed of the car is proportionally reduces. Several gears are used, giving wide
range of speed ratios between the engine and the wheels. In automotive technology there are two
basic types of Transmission; manual transmission and automatic transmission.

B. Automatic transmission (also called automatic gearbox)

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AT is a type of vehicle transmission that can automatically change ratios as the vehicle moves,
freeing the driver from having to shift gears manually. Most automatic transmissions have a
defined set of gear ranges, often with a parking pawl feature that locks the output shaft of the
transmission stroke face to keep the vehicle from rolling either forward or backward.

The major parts of automatic transmission

Figure 4 TRANSMISSION COMPONENTS

Automatic transmission components

Torque convertor
The torque converter is mounted on the input side of the transmission gear train and is bolted to
the rear end of the engine crankshaft via the drive plate. The torque converter is filled with
automatic transmission fluid, and either multiplies the torque generated by the engine and
transmits the increased torque to the transmission, or it functions as a fluid coupling which
transmits the engine torque to the transmission.
Roles of torque converter
Multiplying the torque generated by the engine.
Serving as an automatic clutch, which transmits (or does not transmit) the engine torque to the
transmission.
Absorbing the torsional vibration of the engine and drive train.

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Serving as a flywheel to smooth out engine rotation.
Driving the oil pump of the hydraulic control system.
Common Transmission Problems THAT I HAVE SEEN
When you hop in your car to head to work in the morning and it won’t move, or when it begins
making odd noises or sensations while running.
How will you know if something is wrong?
A transmission fluid leak (look for red or brownish-red spots or pools on your driveway).
Your transmission shifts rough or slips out of gear, which may feel like the engine is revving up
and down with no increase or decrease in vehicle speed.
Your transmission won’t go into gear (the vehicle will not move).
Your transmission is clunking, grinding, whirring, shuddering, or making a humming noise.
The Most Common Transmission Issues
Leaking Seals: When your vehicle’s transmission is low on fluid due to failed seals that cause a
leak, it can lose so much fluid that the internal components don't work correctly or fail.
Worn-Out Clutch: In manual transmissions, there are several components to the clutch that wear
out or can fail over time, causing it not to work correctly.
Old or Dirty Filter: Filters need to be replaced periodically, as they can become dirty or
clogged. These issues can restrict the movement of fluid in the transmission, which can cause it
not to work properly or fail.
Broken Sensors: Transmissions rely on electronic sensors to operate correctly, and if one of them
fails, it can cause your transmission not to work correctly or even cause damage.
Worn-Out Torque Convertor: In automatic transmissions, our vehicle relies on the torque
converter to transfer power. When it fails, your vehicle won’t operate correctly.
Worn-Out Gears: As gears age, they begin to wear out, which can cause slipping (especially in
manual transmissions).
Overheating: Just like your vehicle’s engine, your car’s transmission depends on fluids to help
keep it cool. If your car has low fluid or dirty or worn-out fluid, it can overheat.
Bad Shift Solenoids: Solenoids are similar to sensors in that they tell the transmission what to do,
but failed solenoids may be more expensive to replace.
Broken Bands: Your transmission has many bands that help bind the gear sets together that
enable smooth, repetitive shifting. If they begin to wear, the components will begin not to engage
and may break.

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Software Failure: Besides sensors, your transmission uses software components to operate
correctly and communicate with the rest of the systems in your car. If there is a software failure,
your transmission may not work properly.
Fully hydraulic automatic transmission service
Tools and Equipment Needed
General Tools:
Socket and Wrench Set: For removing bolts and fasteners.
Torque Wrench: To ensure bolts are tightened to the manufacturer’s specifications.
Snap Ring Pliers: For removing and installing snap rings in the transmission.
Seal Puller and Installer: To remove and install seals without damaging components.
Bushing Driver Set: For installing bushings in the transmission case.
Dial Indicator: For measuring end-play of shafts and components.
Transmission Jack: To support and remove the transmission from the vehicle.
Pry Bars and Picks: For removing components that are stuck or difficult to access.
Feeler Gauge: To measure clutch clearance and band adjustment.
Rubber Mallet: For tapping components into place without damage.
Clean Workspace: A large, clean area to lay out parts and components.

Specialized Tools:
Valve Body Holding Fixture: To securely hold the valve body during disassembly and
reassembly.
Manual Shift Detent Spring Compressor: To safely compress and release the detent spring.
Clutch Spring Compressor Tool: For compressing clutch pack assemblies.
Hydraulic Test Bench (Optional): To test the operation of the valve body and other hydraulic
components.
Assembly Lubricant or Transmission Assembly Gel: To lubricate seals, bushings, and O-rings
during assembly.
Transmission

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DISASSEMBLY AND ASSEMBLY

Figure 6.Transmission components disassembly

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Con

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Figure 5 plate clutch disassembled

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Assembly Procedure
1. Prepare for Assembly
Lubricate components: apply assembly lubricant or transmission fluid to all seals, bushings, and
moving parts.
Organize components: arrange all parts in the order they will be reassembled.
2. Assemble the Valve Body
Reinstall Valves and Check Balls: Install all valves, check balls, and springs in their correct
positions. Ensure they move freely and smoothly.
Reassemble Valve Body Halves: Reassemble the valve body halves, torqueing the bolts to the
specified value.
Install Accumulators and springs: Reinstall the accumulators and springs in their correct
positions.
3. Reassemble the Transmission Internals
Install New Seals and Bushings: Use the seal installer to install new seals and bushings in the
transmission case.
Install Clutch Packs and Shafts: Reassemble and install the clutch packs, ensuring proper
clearance and alignment.
Install Planetary Gear Sets: Reinstall the planetary gear sets, checking for proper engagement
with the other components.
Reinstall the Front Pump Assembly: Reinstall the pump, ensuring it is aligned with the input
shaft and secured properly.
6. Test and Adjust
Test Drive the Vehicle: Start the engine and allow the transmission to warm up. Check for proper
shifting and smooth operation.
Check Fluid Levels: After the test drive, recheck the transmission fluid level and add more as
needed.
Final Checks
Monitor for Leaks: Inspect the transmission and lines for any signs of leaks.
Adjust Bands and Linkages: If applicable, adjust the bands and linkages to the manufacturer’s
specifications.

2.2 working experience

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2.2.2 CHALLENGES IN ETHIOPIAN AIRLINES
The challenges that are faced us are:
 Needs more safety that is big difference from our previous mostly on dressing style
 Difficult to take with communication devices such as cell phone, music devices, radio and
etc.
 Less excuse to non-discipline persons
 Not familiarizing with names of component and tools quickly
Measures taken to overcome the challenges
 Dressing safety shoes and clothes
 Not to take the communication devices which are not permitted from the company
 To be an honest in achieving of good discipline
 Respect what is required from us

Projects carried out

 I have participated in problem solving projects which will be described in group report .
we manufactured valve lapping prototype which can lap with a little modification . we
were also in progress to manufacture simple pulley , but ceased due to lack of thin shit
metal.

2.3 Learning outcomes

2.3.1 THE BENEFITS WE GAINED FROM INTERNSHIP
We gained opportunity for learning useful employment skills on real jobs under actual working
condition.
Provide me highly competent professional support
Help me to select and develop my future talents
Benefit we gained in terms of up grading my theoretical knowledge.
Develop our knowledge to solve problems scientifically Also we can develop more the practical
skill.
Knowing how to learn new knowledge from experienced workers(by politely questing)
Benefits we gained in terms of improving team-playing skills
We developed various techniques to solve problems while maintaining a positive relationship
with team members.
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The worked cooperatively on group project with team members.
The positive feedback to motivate team members.
The Benefits based on work ethics in internship program we gained
Developing work ethics, which we can give value for our job.
We have learned a work ethics and a work values.
We have developed a good work habit.
Benefit we gained in terms of improving my practical skills
We gained good work-related experience
We apply practical and professional work place skill
Also we applied academic knowledge to practical situation
Benefit we gained in terms of improving industrial problem solving ability
Resolving customers concern in relation to complex project issue
We can developed practical solution for the problem
How to apply range of strategies to problem solving
2.4. Applications of Theory and Soft Skills
2.4.1 How Did Your Supervisor Help You to Succeed in the Assignment You Were Given?
My supervisors played a key role in helping me succeed in my assignments. Ms .Meron , in particular,
provided clear instructions on what was expected of me and gave regular feedback on my performance.
Whenever I encountered a challenge or had difficulty understanding a particular task, she was always
available to offer guidance and clarification. Her hands-on approach, especially during complex tasks like
engine disassembly, allowed me to learn by doing while having the support I needed to correct mistakes
and improve my technique.
In the laundry department, the team leaders were instrumental in helping me understand the operation and
maintenance of industrial laundry machines. They demonstrated how to handle each machine safely and
provided step-by-step instructions on tasks like cleaning the evaporator coil and checking the AC unit.
They also encouraged me to ask questions whenever I was unsure, which made me feel comfortable and
confident in my work.

2.4.2 What Qualities Did I Develop Which Allowed me to Succeed in my Daily Duties?

Throughout the internship, I developed several key qualities that allowed me to succeed in my
daily duties. One of the most important qualities I gained was attention to detail. Whether I was
checking the refrigerant levels in an AC unit or disassembling an engine, I learned that small
mistakes could have significant consequences. By focusing on every detail and double-checking

34
my work, I was able to ensure that the machines and vehicles I worked on were properly
maintained and safe to use.

Another quality I developed was adaptability. Since I worked in two very different departments, I
had to quickly adapt to new environments and tasks. In the laundry shop, I learned how to handle
delicate machines like the dry cleaning unit, while in the automotive shop, I became familiar with

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 Chapter Three
Conclusion and Recommendation
3.1 Conclusion

During my internship at Ethiopian Airlines, particularly at the Bole International Airport, I

gained significant practical experience in both the laundry and automotive departments. The
hands-on tasks such as maintaining laundry machines and servicing airport vehicles gave me
deep insight into the daily operations of a large-scale commercial enterprise. Ethiopian Airlines,
as one of the most advanced and well-established airlines in Africa, provided a structured
environment that emphasized safety, discipline, and teamwork. By working alongside
experienced professionals, I developed essential skills and learned about the importance of
preventive maintenance in the aviation industry.

In addition to technical knowledge, I also improved my ability to adapt to new environments,

handle advanced machinery, and follow strict safety protocols. While there were challenges,
such as adhering to safety regulations and adjusting to a professional work setting, the
experience was invaluable in shaping my career trajectory.

3.2 Recommendation

Enhanced Safety Training: The internship program could benefit from more detailed safety
training sessions, especially given the use of hazardous chemicals like tetrachloroethylene
(PERC) in the laundry department. Regular safety refreshers would reinforce the importance of
safety protocols.

Structured Feedback Mechanism: Introducing a formal feedback system where interns receive
constructive feedback regularly would help improve performance and skill acquisition.

Access to Learning Resources: Providing access to manuals or resources related to machine

operation and maintenance would be beneficial, particularly for technical tasks like engine repair
and AC unit troubleshooting.

Greater Use of Technology: Integrating digital communication tools or platforms for easier
coordination and task management could enhance the efficiency of operations, especially in large
departments like automotive maintenance.

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Reference

[3] Official website of Ethiopian Airlines - www.ethiopianairlines.com

[4] International Air Transport Association (IATA) - www.iata.org

1. "Automotive Engineering: Powertrain, Chassis System and Vehicle Body" by David C. V. H.

R. and D. G. B.
2. "Machinery's Handbook" by Erik Oberg et al.
3. "Internal Combustion Engine Fundamentals" by John B. Heywood
5. "Automotive Brake System" by Robert H. Smith

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