Aircraft Maintenance practices introduction

Maintenance
 The process of keeping something in useable
condition by checking or repairing it on regular
basis.
Maitenance Practice-1

Practice
 Actual doing of something rather than ideas
 Way of doing something
 Doing an activity or training on regular basis to
improve skills
 Habit or Custom

Maintenance Practice
 This subject deals with the way of keeping something
in useable/good condition

Why this subject?
 Prime objective of an AME is to maintain an aircraft in
airworthy condition so that it can fly safe and reach its
destination with all its passenger safely.
 If there is an error in maintenance or ignorance of
maintenance procedure by maintenance personnel
then the life of passengers and crews and machine is at
stake.
 So it is important that the persons involved in
maintenance of aircraft must have proper knowledge
of procedures and practices involved in maintenance
of aircraft

Maintenance Practice
This Subject is divided in 03 parts
- Maintenance Practice -1- Ist Semester
- Maintenance Practice -2- IInd Semester
- Maintenance Practice -3-IIIrd Semester

Maintenance Practice-1
 Safety Precaution-Aircraft and Workshop
 Workshop Practices
 Tools
 Operation, Function and Use of Electrical General Test
Equipment
 Fits and Clearances
 Weight and Balance

Chapter-1
Safety Precaution
Aircraft
and
Workshop

Safety Precaution
An action taken in advance to
protect against possible danger,
failure, or injury.

Aircraft
 Any machine which can derive support in the
atmosphere from reactions of the air other than
reactions of the air against the earth's surface
and includes balloons whether fixed or free,
airships, kites, gliders and flying machines.
(source: Aircraft Rules 1937)
 Any vehicle designed to be supported by air,
heavier or lighter than air, mechanically or
non-mechanically driven

Workshop
 A room or shop where work is done
It includes
-Aircraft hanger maintenance bays
-Mechanical and electrical bays
-Machine shops
-Cleaning plants
-Battery rooms
-Basic bench tool work areas

Accident
 An unfortunate incident that happens unexpectedly
and unintentionally, and may result in injury or death
of people and/or damage to equipments or facilities
 Accident always have a cause.
 That cause may be
-unsafe human condition
-unsafe environmental condition (Humans are
responsible for choosing or creating unsafe
condition )

Hazard
 anything that has the potential to create danger
and thus harm.
 Most hazards are dormant or potential, with only a
theoretical risk of harm; however, once a hazard
becomes "active", it can create
an emergency situation.

Hazard
 Hazards occurs as a result of day-to-day activities
in and around the workplace. e.g.
 Slippery floor
 Defective tools
 Spilled chemicals
 Overconfidence
 Fatigue
 Stress
 Lack of fitness
 Inappropriate or incorrectly worn dresses

Risk
 ‘risk is the likelihood/chance that a person may be harmed
or suffers adverse health effects if exposed to a hazard.’
 The level of risk is often categorised upon the potential
harm or adverse health effect that the hazard may cause,
the number of times persons are exposed and the number
of persons exposed.
 Exposure to airborne asbestos fibres will always be
classified as high because a single exposure may cause
potentially fatal lung disease, whereas the risk associated
watching a television for a short period could be
considered to be very low as the potential harm or adverse
health effects are minimal.

Risk and Hazard
 The terms Hazard and Risk are often used
interchangeably but this simple example explains the
difference between the two.
 If there was a spill of water in a room then that water
would present a slipping hazard to persons passing
through it. If access to that area was prevented by a
physical barrier then the hazard would remain though
the risk would be minimised.
 So, Risk and Hazard collectively leads to Accident.

Risk Assessment for Safety
 A risk assessment would involve identifying a
hazard and then evaluating the risk in the light of
precautions to reduce the danger or remove it.
 First hazard must be recognized; then they must be
assessed; and finally, if necessary, they must be
controlled.

Recognition of Hazard
 Slippery floors
 Untidy work areas
 Cluttered walkways
 Insecure handrails
 Defective tools
 Spilled chemicals
 Inadequate lighting
 Poor ventilation
 Lack of equipment
 Excessive noise

Recognition of Hazard
 APATHY
 BOREDOM
 NEGLIGENCE
 COMPLACENCY
 DISOBEDIENCE
 TOMFOOLERY
 SHOWING-OFF
 OVER CONFIDENCE
 FATIGUE
 STRESS
 LACK OF FITNESS
 INAPPROPRIATE OR
INCORRECTLY WORN
DRESSES
 LONG HAIR
 DRUG AND ALCOHOL
ABUSE

Safety Precaution- Aircraft

Airport
 An airport is a location where aircraft such
as fixed-wing aircraft, helicopters,
and blimps take off and land. Aircraft may
be stored or maintained at an airport. An
airport consists of at least one surface such
as a runway for a plane to take off and land,
a helipad, or water for takeoffs and landings,
and often includes buildings such as control
towers, hangars and terminal buildings.

Airside and Landside
 Airports are divided into landside and airside
areas.
 Landside areas include parking lots, public
transportation train stations and access roads. It is
the area accessible to normal public.
 Airside areas include all areas accessible to
aircraft, including runways, taxiways and ramps.
 Access from landside areas to airside areas is
tightly controlled at most airports.

Airside and Landside

APRON
 Area that accommodates aircraft for the
purpose of loading/off-loading passengers
and cargo, refueling, parking and
maintenance.

APRON
 Tarmac: Though commonly used to describe the area
where planes park, tarmac isn’t officially a place. That
word is the name of a product produced by a British
company that produces a surface coating that is
applied to roads and airfields.
 Using tarmac to describe where planes park is like
calling the area outside a building where cars park “the
concrete” instead of calling it the parking lot. Tarmac®
with a capital “T” is a registered trademark.

APRON
 Ramp: It’s a common unofficial term that is very much
in use at airports of some American and Asian
countries.

APRON
 Apron: This is in fact the official term used by both the
International Civil Aviation Organization (ICAO), which
advises on aviation practices worldwide, and the Federal
Aviation Administration (FAA), which regulates aviation in
the U.S., to designate the area at the airport where parked
and serviced at airports.
 The apron is a busy place. It’s the part of the airport where
vehicles and airplanes share the same space. The many
movements on the apron are not generally controlled by
the air traffic control tower.

Maneuvering Area
 Area other than apron, used for the movement
of the aircraft on the ground and for the
taking-off and landing.

Movement Area
 Comprises both the maneuvering area and the
apron.

Taxiway
 Path connecting the runway to other aircraft facilities,
such as hangers and apron.

Runway
 A strip of land or water from which aircraft can takeoff
and land on airport.

Hanger
 An enclosed structure designed to hold the aircraft in
protective storage.

Points to be Observed
 Apron environment is often a busy one and be
aware of the danger.
 Aware with airport operations instructions
rules.
 Entry to the maneuvering area require clearance
from local air traffic controller.

Airport Marking
 Airport markings are used to mark structures, and
path so that these can be used by required
personnel or vehicles without confusion.
 Both paint and lights are used for marking so
that, markings are visible in day as well as night.
 Vehicle routes – white line
 Aircraft routes – yellow line
 Pedestrian routes – green line
 Delineation between apron and maneuvering
area – double white lines

Aircraft Taxiway
 The taxiway centre-line is a single continuous yellow
line, 6 inches (15 cm) to 12 inches (30 cm) in width.
This provides a visual cue to permit taxiing along a
designated path.
 Taxiway edge marking are of two types:
 Continuous: Consist of a continuous double yellow
line, with each line being at least 6 inches (15 cm) in
width spaced 6 inches (15 cm) apart. They are used to
define the taxiway edge from the paved surface not
intended for use by aircraft.

Aircraft Taxiway
 Dashed Markings. define the edge of a taxiway or taxi-lane on a
paved surface where the adjoining pavement to the taxiway edge
is intended for use by aircraft. e.g., an apron. Dashed taxiway
edge markings consist of a broken double yellow line, with each
line being at least 6 inches (15 cm) in width, spaced 6 inches (15
cm) apart (edge to edge). These lines are 15 feet (4.5 m) in length
with 25 foot (7.5 m) gaps.
 Identified by blue edge light and sometimes green centre line
lights.
 Also have red stop bar lights at various holding points.

Aircraft Taxiway

Apron
Normally illuminated by an array of overhead
pylon lights.

Runways
 A line of lights on an airfield or elsewhere to guide aircraft
in taking off or coming in to land or an illuminated runway
is sometimes also known as a Flare Path.
 Runway center Line: embedded in surface of runway at 50
ft interval along runway center line. White light is used for
this except last 900 m, alternate white and red for next
600m, and red for last 300m.
 Runway edge lights: white elevated lights that run the
length of the runway on either side. On precision
instrument runways, the edge-lighting becomes yellow in
the last 2,000 ft (610 m) of the runway, or last third of the
runway, whichever is less.

Vehicles
 For driving in the movement area personnel must
require Airfield Driving Permit (ADP).
 Aircraft have priority over all vehicles in the
airside.
 Fire and rescue vehicles on emergency call out
have priority.
 Pedestrian have priority on apron.

Vehicles
 All vehicles display a roof mounted yellow flashing
obstruction light in movement area.
 Fire and rescue vehicles display a flashing blue
light when emergency callout.
 In apron speed of vehicles restricted to 15 mph.
 Vehicles use dipped headlight while moving .
 Vehicles must not approach aircraft until the
aircraft is choked and engines have been shut
down and anti-collision lights have been switched
off.

Vehicles
 Vehicles have to positioned so that they do not have to
reverse in order to leave the zone.

Clothing
 Wear approved high visibility anoraks or tabards at
all times.

Noise
 Noise from turbine engine can cause temporary or
long-term damage to hearing.
 This noise also blankets the sound of approaching
vehicles and will drown out shouted warnings.
 Personnel working on airport needs to wear the ear
defenders.

Engine
 Personnel must be alert at the time of starting of
engine not to stray in front of engine intakes,
propellers or into the jet-blast.
 Even at low power setting hot jet blast can be left 100ft
behind the aircraft.
 At full power some engines can even pull a full grown
man into intake. And can throw a truck, if is in the
vicinity of engine’s exhaust.
 So areas coming directly under the operation of engine
should be avoided.

Engine
 Video

Fuel Spill
 The source of spill should be shutoff .
 All sources of ignition should be removed.
 All engines in Ground Power Unit and vehicles in the
area should be turned off.

Task Lighting
 Overhead pylon lights are capable of illuminating the
area but this does not help when personnel are
working under aircraft.
 Lighting in these area are well below what would
considered adequate for conducting maintenance task.
 Hand torches may seem to be an ideal solution but
their batteries gradually deplete and they do restrict
user to one handed operation.

Task Lighting
 Ensure that the light being used during maintenacne
is of approved flameproof type.

Foreign Object Damage (FOD)
 Unwanted object other than objects required aircraft
maintenance and operation are known as Foreign
Object. Cuts of locking wire, split pins, plastic
bags, stones etc.
 Can damage the turbine engine.
 Can cause serious damage to the moving propeller
blades.


Working on A/c
 Appropriate clothing and suitable footwear, do not
wear jewellery or loose items.
 Don’t carry means of ignition.
 Be aware that it takes time to gain fully night vision
when moving from a brightly lit area to a dark
place.
 Always ground aircraft before fueling, de-fueling
or work on oxygen system.
 Approved fire extinguisher should be located at
easily accessible area.

Working on A/c
 Aircraft should be correctly choked, and appropriate
covers and locks should be used when required.
 Before moving flight control surfaces ensure that
movement is not obstructed by ground equipment,
and don’t posses hazard to personnel.
 Specified procedure and must be followed during
removal or installation of aircraft’s component.
 Don’t use tools carelessly as this may scratch the
aircraft paint finish and will introduce corrosion.

Working on A/c
 Ensure that aircraft electrical bonding wires and static
discharges are left intact and connected after work has
been completed.
 Always take extra care while handling the aircraft
fluids. As there spillage may damage other aircraft
parts.
 Approach the helicopter in view of the pilot.
 Never approach a helicopter carrying anything with a
vertical height that the blades could hit. This could
cause blade damage and injury to the person.

Shop Safety
 The highest standards of orderly work
arrangements and cleanliness should be observed
during the maintenance of aircraft.
 Where continuous work shifts are established, the
outgoing shift should remove and properly store
personal tools, rollaway boxes, all work stands,
maintenance stands, hoses, electrical cords, hoists,
crates, and boxes that were needed for the work to
be accomplished.

Shop Safety
 Signs should be posted to indicate dangerous
equipment or hazardous conditions. There should also
be signs that provide the location of first aid and fire
equipment.
 Safety lanes, pedestrian walkways, and fire lanes
should be painted around the perimeter inside the
hangars. This is a safety measure to prevent accidents
and to keep pedestrian traffic out of work areas.

Shop Safety
 Technicians and supervisors should watch for their
own safety and for the safety of others working around
them.
 If other personnel are conducting their actions in an
unsafe manner, communicate with them, reminding
them of their safety and that of others around them.

Electrical Safety
 It is known that when electricity is applied to the
human body, it can create severe burns.
 In addition, the nervous system is affected and can be
damaged or destroyed.
 To safely deal with electricity, the technician must
have a working knowledge of the principles of
electricity, and a healthy respect for its capability to do
both work and damage.

Electrical Safety
 Wearing or use of proper safety equipment can provide a
psychological assurance at the same time it physically
protects the user.
 The use of rubber gloves, safety glasses, rubber or grounded
safety mats, and other safety equipment contributes to the
safety of the technician working on or with electrical
equipment.
 Two factors that affect safety when dealing with electricity
are fear and overconfidence. While both a certain amount
of respect for electrical equipment is healthy and a certain
level of confidence is necessary, extremes of either can be
deadly.

Electrical Safety
 Lack of respect is often due to lack of knowledge.
Personnel who attempt to work with electrical
equipment and have no knowledge of the principles of
electricity lack the skills to deal with electrical
equipment safely.
 Overconfidence leads to risk taking. The technician
who does not respect the capabilities of electricity will,
sooner or later, become a victim of electricity’s
awesome power.

Fire Safety
 Anytime current flows, whether during generation or
transmission, a byproduct of that flow is heat. The
greater the current flow, the greater the amount of
heat created.
 When this heat becomes too great, protective coatings
on wiring and other electrical devices can melt,
causing shorting, which leads to more current flow
and greater heat. This heat can become so great so that
metals can melt, liquids vaporize, and flammable
substances ignite.

Fire Safety
 To prevent electrical fires :
- keep the area around electrical work or electrical
equipment clean, uncluttered, and free of all
unnecessary flammable substances.
- Never place wires or cords where they will be walked
on or run over by other equipment

Compressed Gas
 Storage room for Gas cylinder should be well ventilated
 Cylinders should not be exposed to sunlight.
 Gas cylinders should not be laid on damp ground.
 Lightning for stores containing combustible gas cylinder
should be flameproof.
 Breathing oxygen and welding oxygen should be segregated
and properly labeled to avoid confusion.
 Grit, dirt and oil should be prevented from entering the
cylinder valves.
 Acetylene cylinder should be stored vertically.

Compressed Gas
 Compressed air, like electricity, is an excellent tool as
long as it is under control.
 Inspect air hoses frequently for breaks and worn spots.
Unsafe hoses should be replaced immediately.
 Keep all connections in a “no-leak condition.”
 Air used for paint spraying should be filtered to
remove oil and water.
 Never use compressed air to clean hands or clothing.
Pressure can force debris into the flesh leading to
infection.

Compressed Gas
 Air hoses should be straightened, coiled, and properly
stored when not in use.
 Many accidents involving compressed gases occur
during aircraft tire mounting. To prevent possible
personal injury use appropriate lifting and mounting
devices in mounting or removing heavy aircraft tires.

Welding Safety
 Welding should be performed only in designated
areas.
 Any part to be welded should be removed from the
aircraft, if possible.
 A welding shop should be equipped with proper
tables, ventilation, tool storage, and fire prevention
and extinguishing equipment.
 Welding on an aircraft should be performed outside, if
 possible.

Welding Safety
 If welding in the hangar is necessary, observe these
precautions:
 During welding operations, there should be no open
fuel tanks, and no work on fuel systems should be in
progress.
 No painting should be in progress.
 No aircraft are to be within 35 feet of the welding
operation.
 No flammable material should be in the area around
the welding operation.

Welding Safety
 Only qualified welders should be permitted to do the work.
 Fire extinguishing equipment of a minimum rating of 20B
should be in the immediate area with 80B rated equipment
as a backup.
 Aircraft being welded should be in towable condition, with
a tug attached, and the aircraft parking brakes released. A
qualified operator should be on the tug, and mechanics
available to assist in the towing operation should it become
necessary to tow the aircraft. If the aircraft is in the hangar,
the hangar doors should be opened.

Fire Protection
 Rapid oxidation, accompanied by a noticeable release
of heat and light, is called combustion or burning.
 Requirements for Fire To Occur:
 Fuel: something that will, in the presence of heat,
combine with oxygen, thereby releasing more heat and
as a result reduces itself to other chemical compounds;
 Heat: accelerates the combining of oxygen with fuel, in
turn releasing more heat
 Oxygen: the element which combines chemically with
another substance through the process of oxidation.

Fire Protection
 Classification of Fires:
 For commercial purposes, the National Fire Protection
Association (NFPA) has classified fires into three basic
types: Class A, Class B, and Class C.
 Class A fires occur in ordinary combustible materials,
such as wood, cloth, paper, upholstery materials, and
so forth.
 Class B fires occur in flammable petroleum products
of other flammable or combustible liquids, greases,
solvents, paints, and so forth.

Fire Protection
 Class C fires occur involve energized electrical wiring
and equipment.
 Class D fire Class D fires are not commercially
considered by the National Fire Protection Association
to be a basic type or category of fire since they are
caused by a Class A, B, or C fire. Usually Class D fires
involve magnesium in the shop or in aircraft wheels
and brakes, or are the result of improper or poorly
conducted welding operations.

Fire Extinguishers
 Any type of fire can occur during maintenance on or
around, or operations involving, aircraft. There is a
particular type extinguisher which is most effective for
each type of fire.
 Water extinguishers are the best type to use on Class A
fires. Water has two effects on fire: it deprives fire of
oxygen and cools the material being burned.
 Never use water-type fire extinguishers on Class D
fires. Because metals burn at extremely high
temperatures, the cooling effect of water causes an
explosive expansion of the metal.

Fire Extinguishers
 Carbon dioxide (CO2) extinguishers are used for Class
A, B, and C fires, extinguishing the fire by depriving it
of oxygen.
 Additionally, like water-type extinguishers, CO2 cools
the burning material.
 Carbon dioxide (CO2) extinguishers are used for Class
A, B, and C fires, extinguishing the fire by depriving it
of oxygen. Additionally, like water-type extinguishers,
CO2 cools the burning material.

Fire Extinguishers
 Never use CO2 on Class D fires. As with water
extinguishers the cooling effect of CO2 on the hot
metal can cause explosive expansion of the metal.
 When using CO2 fire extinguishers, all parts of the
extinguisher can become extremely cold, and remain
so for a short time after operation. Wear protective
equipment or take other precautions to prevent cold
injury (such as frostbite) from occurring.
 Extreme caution must be used when operating CO2
fire extinguishers in closed or confined areas.

Fire Extinguishers
 Halogenated hydrocarbon extinguishers are most
effective on Class B and C fires. They can be used on
Class A and D fires but they are less effective.
Halogenated hydrocarbon, (commonly called Freon™
by the industry) are numbered according to chemical
formulas with Halon™ numbers.

Fire Extinguishers
 Bromochlorodifluoromethane (Halon 1211),
 chemical formula CBrClF2,
 is a liquefied gas with a UL toxicity rating of 5.
 It is colorless, noncorrosive and evaporates rapidly leaving
no residue.
 It does not freeze or cause cold burns, and will not harm
fabrics, metals, or other materials it contacts.
 acts rapidly on fires by producing a heavy blanketing mist
that eliminates oxygen from the fire source.
 It has outstanding properties in preventing reflash after the
fire has been extinguished.

Fire Extinguishers
 Bromotrifluoromethane (Halon 1301):
 chemical formula CF3Br,
 is a liquefied gas with a UL toxicity rating of 6.
 It has all the characteristics of Halon 1211.
 The significant difference between the two is: Halon
1211 forms a spray similar to CO2, while Halon 1301 has
a vapor spray that is more difficult to direct.

Fire Extinguishers
 Dry powder
 Stored as a fine powder in a blue colored
extinguisher, pressurized by a CO2 or a nitrogen
cartridge.
 Suitable for brake fires and class B, C and D fires.
 Has a little cooling effect and fires may re-ignited.

Fire Extinguishers
 Dry powder extinguishers: while effective on Class B
and C fires, are the best for use on Class D fires. Dry
powder is not recommended for aircraft use (except on
metal fires as a fire extinguisher) because the leftover
chemical residues and dust often make cleanup
difficult, and can damage electronic or other delicate
equipment.

Fire Extinguishers
Foam:
 Two types of foam
 Fluoroprotein (used on class B fires)
 Aqueous film (used on class A & B fires)
 Not suitable for class C and D fires.
 Stored in white or cream colored extinguishers
pressurized with CO2

Inspection of Fire Extinguishers
 Fire extinguishers should be checked periodically
utilizing a checklist. If a checklist is unavailable, check
the following as a minimum:
• Proper location of appropriate extinguisher
• Safety seals unbroken
• All external dirt and rust removed
• Gauge or indicator in operable range
• Proper weight
• No nozzle obstruction
• No obvious damage

Identifying Fire Extinguishers
 Fire extinguishers should be marked to indicate suitability
for a particular class of fire.
 The markings should be placed on the fire extinguisher and
in a conspicuous place in the vicinity of the fire
extinguisher.
 When the location is marked, however, extreme care must
be taken to ensure that the fire extinguisher kept at that
location is in fact the type depicted by the marking. In
other words, if a location is marked for a Class B fire
extinguisher, ensure that the fire extinguisher in that
location is in fact suitable for Class B fires.

 Markings should be large enough and in a form that is
easily seen and identifiable by the average person with
average eyesight at a distance of at least 3 feet.
 Where markings are applied to wall panels, and so
forth, in the vicinity of extinguishers, they should be
large enough and in a form that is easily seen and
identifiable by the average person with average
eyesight, at a distance of at least 25 feet.

Using Fire Extinguishers
 When using a fire extinguisher, make sure you have
the correct type for the fire. Most extinguishers have a
pin to pull that will allow the handle to activate the
agent. Stand back 8 feet and aim at the base of the fire
or flames. Squeeze the lever and sweep side to side
until the fire is extinguished.

Oils
 Specified for components on the basis of their
properties in relation to operating conditions of
the component.
 High viscosity oil- for heavily loaded component at
high temperature.
 Low viscosity oil- for lightly loaded application at
low temperature.

Oils
 Turbine engine oils
 Are low viscous, synthetic ester base formed from
cocktail of chemical compounds.
 Type 1- first generation in older type engines
 Type 2 – withstand the high temperature of later
engines.
 Not compatible with each other.

Oils
 Ester based fluid
 hygroscopic nature.
 Care in dispensing oil and with container.
 Aggressive to most of the paints finishes.
 Polyurethane provides best protection with them.

Oils
 Never mix type-1 and type-2.
 Wear protective gloves, apron and face shield when
handling.
 Wash hands before smoke, eat or drink.
 Use correct dispensing equipment.
 Follow the correct replenishment procedure.

Chemicals
 Flammable Chemicals:
 Spark, heat or a naked flame may ignite.
 At its flash point may ignite.
 Like fuels, oils, solvents and paints.
 Prevent them with exposed to source of heat.
 Adequate ventilation to prevent the vapor
concentration.
 Suitable containers
 Adequate fire extinguisher
 Wear gloves and a respirator

Chemicals
 CORROSIVE CHEMICALS:
 React with and attack metals and burn the skin.
 Etching agents, battery electrolyte and corrosion fluids.
 Mostly in liquid form but some be in powder form.
 Adequate type of container.
 Avoid the contact with sensitive material.
 Clean the surface adequately.
 Wear suitable clothing, goggles or a face shield, gloves and apron.
 Take the precaution for fire flammable or toxicity.
 Check the eye wash facility.

Chemicals
 Toxic Chemicals:
 poisonous, can cause injuries or diseases in short
term or long term. (asthma, cancers etc.)
 Have number of routes in the body- Breathe in the
vapor, skin can absorb, carry substances onto food
and into drink and ingest them.
 Solid chemical- harmful dust, hazardous fumes.
 Required personal protective equipment.

Chemicals
 Reactive Chemicals:
 Are those that experience a chemical change when
exposed to other chemicals.
 Reaction may have slow change or voilent explosion.
 Some create high temperature causes to fire.
 Surface treatment- Alchrom, Cd-plating involve
reactive chemicals.
 Some create toxic vapors- phosgene, chlorine and
ferro-cyanide.

Safety Around Hazardous Materials
 A Material Safety Data Sheet (MSDS) is a document that
contains information on the potential hazards (health, fire,
reactivity and environmental) and how to work safely with the
chemical product. It is an essential starting point for the
development of a complete health and safety program.
 MSDSs are prepared by the supplier or manufacturer of the
material. It is intended to tell what the hazards of the product
are, how to use the product safely, what to expect if the
recommendations are not followed, what to do if accidents
occur, how to recognize symptoms of overexposure, and what
to do if such incidents occur.

 MSDS formats can vary from source to source within a
country depending on national requirements.
 It is intended to provide workers and emergency
personnel with procedures for handling or working
with that substance in a safe manner, and includes
information such as physical data (melting
point, boiling point, flash point, etc.), toxicity, health
effects, first aid, reactivity storage, disposal, protective
equipment, and spill-handling procedures.

 The most observable portion of the Material Safety
Data Sheet (MSDS) label is the risk diamond.
 It is a four color segmented diamond that represents
Flammability (Red), Reactivity (Yellow), Health (Blue),
and special Hazard (White). In the Flammability,
Reactivity, and Health blocks, there should be a
number from 0 to 4. Zero represents little or no hazard
to the user; 4 means that the material is very
hazardous.

 The special hazard segment contains a word or
abbreviation to represent the special hazard. Some
examples are: RAD for radiation, ALK for alkali
materials, Acid for acidic materials, and CARC for
carcinogenic materials. The letter W with a line
through it stands for high reactivity to water

Risk Diamond
Health
Special Hazard

Safety Signs and Signals

Safety Around Machine Tools
 Hazards in a shop’s operation increase when the
operation of lathes, drill presses, grinders, and other
types of machines are used. Each machine has its own
set of safety practices.

 Drill Press: can be used to bore and ream holes, to do
facing, milling, and other similar types of operations.
 The following precautions can reduce the chance of injury:
• Wear eye protection.
• Securely clamp all work.
• Set the proper RPM for the material used.
• Do not allow the spindle to feed beyond its limit of travel
while drilling.
• Stop the machine before adjusting work or attempting to
remove jammed work.
• Clean the area when finished.

Drill Press

 Lathes: are used in turning work of a cylindrical
nature. This work may be performed on the inside or
outside of the cylinder. The work is secured in the
chuck to provide the rotary motion, and the forming is
done by contact with a securely mounted tool.

 Lathes : following precautions can reduce the chance of
injury:
• Use sharp cutting tools.
• Allow the chuck to stop on its own. Do not attempt to stop
the chuck by hand pressure.
• Examine tools and work for cracks or defects before starting
the work.
• Do not set tools on the lathe. Tools may be caught by the
work and thrown.
• Before measuring the work, allow it to stop in the lathe.

 Milling machines: are used to shape or dress; cut
gear teeth, slots, or key ways; and similar work.
 The following precautions can reduce the chance of
injury:
• Clean the work bed prior to work.
• Secure the work to the bed to prevent movement
during milling.
• Select the proper tools for the job.
• Do not change the feed speed while working.

 Milling machines

 Grinders: are used to sharpen tools, dress metal, and
perform other operations involving the removal of small
amounts of metal.
 The following precautions can reduce the chance of injury:
• Wear eye protection even if the grinder has a shield.
• Inspect the grinding wheel for defects prior to use.
• Do not force grinding wheels onto the spindle.
• Do not stand in the arc of the grinding wheel while
operating, in case the wheel explodes.
• Do not force grinding wheels onto the spindle. They fit
snugly, but do not require force to install them.

 Grinders:

Battery Maintenance
 Battery is an integral part of the electrical system
in aircraft.
 Two types of batteries are used: Pb-acid and Ni-
Cd.
 Charging rooms are potential very dangerous area.
 Hydrogen is vented during every stage of Pb-acid
battery charging.

Battery Maintenance
 There must be separate room for Pb-acid and alkaline
battery charging, repair/maintenance and electrical
supply and storage.
 All tools and equipment must be separate and marked
for the purpose.
 All electrolyte and neutralizing agents containers must
be clearly marked.
 Charging rooms – well vented, explosion proof lighted
and with air extraction system.

Battery Maintenance
 Ambient temperature in the charging rooms must be
maintained within limits. e.g. lead acid- below 27° C
and Ni-Cd 21° C.
 Floor – Level, dry, dust free, proof against acid or alkali
e.g. concrete.
 Bench: Height should be 20 inch from floor, to enable
inspection and reduce lifting effort. Should be made of
latticed panels of waxed wood.
 Co2 type fire extinguisher should be strategically
placed.

Battery Maintenance
 Battery charging supply is normally D.C. but supplied
from A.C. distribution system.
 When disconnecting batteries, the cable should be
removed from the battery first and then from the
charging board.
 Individual charging boards should be mounted
adjacent to each charging point and be mounted
adjacent to each charging point and be mounted
directly above and to rear of the bench to minimize the
need for long connecting cables.

Battery Maintenance
 H2SO4 SPILLAGE- should be washed in solution of
bicarbonate of soda and fresh water. Other
neutralizing agent Ammonia powder or borax
powder.
 Alkaline Solution- washed in saturated solution of
boric acid (crystal and powder) and fresh water.

Aircraft Maintenance practices introduction

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