7.01

Basic Maintenance Training Manual

Module 7 Maintenance Practices7.1 Safety Precautions - Aircraft and Workshop

7.1 Safety Precautions - Aircraft and WorkshopSep04 / THTTCopyright by SR Technics Switzerland

Corresponding with EASA Part-66For training purposes only 7.1 - 1Cat: B2



Safety PrecautionSafety is a keyword in aviation. The greatest possible care is taken to ensure safe-ly; not only in the air, but also on the ground. And this is certainly the case at Air-craft Maintenance Departments. The aircraft maintenance mechanic deals with a

Figure 1: Colours

-IMMEDIATE DANGER!

RED YELLOW

-WATCH OUT!Sep04 / THTTCopyright by SR Technics Switzerland


large number of safety regulations in his work. This apply to working in and on theaircraft as well as working in the workshop and in the hangar.

Everyone must cooperate to prevent accidents and injuries.Your company has endeavored to provide adequate safe-guards, but safety devices alone will not guarantee safety. Ac-cident prevention depends upon the use of approvedpractices and common sense. Be on the alert. Report observed unsafe practices and condi-tions immediately to your supervisor, since delay may resultin a serious injury. Know the location of the nearest medical dispensary.Instructions for handling hazardous materials must be fol-lowed. Further information may be obtained from your safetyofficer, or your supervisor.

ManualsAs explained before, airlines and its related companies such as maintenance de-partments pay optimal attention to safety. This is expressed in all the manuals,safety instructions and procedures. One of the important manuals used by themaintenance department is the Maintenance Manual (AMM/MAI). This manualcontains a large number of general safety regulations.

Danger SignsWithin each Department, bulletin boards, signs and stickers have been installedeverywhere they are needed. Some of them refer to possible danger or indicateescape routes in case of danger. These signs always have three components: col-our, shape and symbol. The meaning of a sign is easy to understand. Figure 2 onpage 2

ColourThere are four main colours that are used for signs: Red, Yellow, Green and Blue.In some cases these colours have been applied directly to the objects or instru-ments. An example is the red colour of a fire extinguisher.

Shapes of SignsDanger signs have three different shapes. Each shape has its own meaning:Circular: prohibitory or mandatory signTriangular: warningRectangular: rescue, instruction or supplementary signHave a look at the four examples shown below.

Figure 2: Signs

-PROHIBITORY SIGN

GREEN BLUE

-POSSIBLE DANGER

-ESCAPE ROUTES -FIRST AID, RESCUE

-SIGN WITH INSTRUCTION (MANDATORY)

s



The Work AreaA clean and tidy area is safer than an untidy work area. It is your employers re-sponsibility to provide and maintain a safe working environment. Practice good house keeping in your work or by keeping the area clean, or-

Figure 3: Work Area HandlingSep04 / THTTCopyright by SR Technics Switzerland


dered and tidy. Always immediately report damaged, worn or inoperative item, or any unsafe

conditions to your supervisor or health and safety representative. Keep all passage ways, aisles and exits clear of obstructions. Remove immediately any oils, paints, greases and other fluids that have been

split on the floor. Keep your immediate work area clean and tidy and do not allow discarded

pieces of material to accumulate. Do not leave tools and materials scattered about thoughtlessly. Put away all the tools you are using. Returning tools to their correct place is not only being safe, it is also being con-

siderate of your workmates who also need the tools. Use the receptacles provided for waste and refuse. Stack materials so that they cannot fall and so that they do not project dan-

gerously. If you are working with oil materials and waste, bins with self closing and seat-

ing lids should be provided.

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Personal Protective Clothing and DevicesIt is the employers responsibility to provide clothing and equipment. Work clothesand specially designed protective clothing are designed for your protection. Wearthe correct clothing and equipment to protect your self from possible serious injury.

Figure 4: Protective ClothingSep04 / THTTCopyright by SR Technics Switzerland


Do not interfere with or misuse any item provided by your employer for health andsafety. Wear plain, tough clothes that are close-fitting, and keep them buttoned up.

Loose sleeve, unbuttoned or torn shirts, or sweaters, ties or loose belts caneasily become caught in revolving machinery.

Your work clothes should be cleaned regularly. Wear cuffless trousers.

Trouser cuffs may cause you to trip or they may catch sparks or they maycatch sparks or harmful substances.

Wear suitable footwear and keep it in good repair.Stout soles or steel midsoles protect against injury form sharp Metal and pro-truding nails. Good uppers protect against burning from hot turnings, drops ofmolten metal, etc. Safety shoes and boots have reinforce toe-caps to protectagainst heavy falling objects.

Keep long hair under a tight-fitting cap or net, as required by regulations.It is you employers duty to ensure machines have guards to Protect employeeswho work closely to the machine. Even so, if your hair is long, it could easily becaught in machinery, such as drilling machine. Many people have been scalped inthis type of accident. Do not wear rings or wrist watches on the job.

Because such items can be caught in moving machinery, it is extremely dan-gerous to wear them in certain types of work. you could lose fingers.

Do not wear earrings, neck chains, pendants and bracelets.All items or personal jewelry worn at work have the potential to cause an ac-cident, or aggravate an injury sustained in an accident.

Wear personal protective equipment suited to the work to be done as shownin Figure 5 on page 5.

Learn the purpose of each item in the wide rage of protective Devices availa-ble.

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Figure 5: Protecting Devices Care in the use of ToolsAs it is your employers duty to maintain safe working conditions, always report anydamaged or worn tools to your supervisor. Tools can cause injuries when and in-correct, improvised or defective tool is used. Also, when the correct tool is not usedSep04 / THTTCopyright by SR Technics Switzerland


carefully or not put away safely, there is a danger of injury. Make sure you select the correct type and size of tool for the job. Check the condition of any tool before you use it. Do not use tools that are worn out or damaged. Maintain tools in good condition and remember that cutting tools need to be

sharp to be safe. Make sure you use each tool in the correct manner. Store and carry your tools safely.

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Danger TagsAll workers must be familiar with the use of warning or danger tags. Danger tags are used to indicate valves or switches that must NOT be operated,as operation could result in injury to workers or damage to equipment.

Figure 6: Warning TagFrontside BacksideSep04 / THTTCopyright by SR Technics Switzerland


The tags should be placed on machines or equipment while they are being in-spected, serviced or cleaned to inform another person NOT to operate the relatedsystem.

The person working on the machine must attach a Danger tag to the controlswitch that supplies power or other input to the machine or work area. The

worker writes his or her name and signature, together with the date of placement,on the Danger tag. When the work is completed, the technician who had attachedthe Danger tag removes it.If more than one person are working on the same equipment, each attaches theirown Danger tag. This is to ensure that the equipment is not turned on until the lasttag is removed.Only the worker whose name and signature appear on the Danger tag, or the su-pervisor, can remove the Danger tag.It is a good practice to advise your supervisor and other workers in the area of yourintended use of the Danger tag.The same procedure should be used for lock-out, using an individual padlock toisolate equipment to be worked on.

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Danger

DO NOTOPERATE

DangerDO NOT REMOVE THIS TAGREMARKS:

Sign:Date:



Safety with Fuels, Oils and ChemicalsSafety in and around your place of work is vital to ensure that accidents to peopleand equipment are prevented. It is essential that all notices and warnings placednear machines are strictly obeyed.

Figure 7: LabelsSep04 / THTTCopyright by SR Technics Switzerland


Precautions should be taken to protect your skin by the application of barriercream or gloves prior to practical work, especially if handling oils, chemicals andgreases which can cause irritation. Containers should be tagged with a label asshown in Figure 7 on page 7. After completion of work ensure all traces are removed by washing. If you areworking with oil materials and waste, bins with self closing and seating lids shouldbe provided.

All accidents, no matter how small, should be reported to your supervisor.The nature of the accident and the treatment received should be entered in

a book to record the accident. Evaluation these data gives more information if anyother action is required.

flammable oxidizer

poisonous irritant/harmful

corrosive explosive



Aviation FuelsThe main safety hazard relates to the risk of fire or explosion with aviation fuelsand methanol/water mixtures. The information in this part is intended to act as aguide to users. It is of a very general nature and is not intended to replace any local

Aviation turbine kerosines are Class II products, which are flammable andshould be stored in closed containers and all sources of ignition excluded. Anyspillage should be treated as a potential fire hazard and/or explosion hazard.Aviation lubricants and hydraulic fluid are unclassified products which areSep04 / THTTCopyright by SR Technics Switzerland


regulations.

Flash Point ClassificationTo apply safeguards to the storage, transport and handling of petroleum liquids,international organisations and authorities classify these liquids according to theirflammability. These classifications sometimes vary slightly from country to coun-try. They are classified according to their closed cup flash points in conformancewith the most widely used system. The classification and guidance is as follows:Class IProducts with a closed cup flash point below 21C should be stored and handledin accordance with local regulations for highly flammable liquids and all sources ofignition excluded. Electrical equipment used must satisfy the requirements of theInstitute of Petroleum Electrical Safety Code or its local equivalent.Class IIProducts with a closed cup flash point from 21C to 55C inclusive should bestored and handled in accordance with local regulations for flammable productsand stored in closed containers and all sources of ignition excluded. Electricalequipment used must satisfy the requirements of the Institute of Petroleum Elec-trical Safety Code or its local equivalent.Class IIIProducts having a closed cup flash point above 55C up to and including 100C.UnclassifiedProducts having a closed cup flash point above 100C.Aviation gasolines and methanol/water mixtures are Class I products. Theirvery low flash points mean that any spillage or leak is a severe fire and/or explo-sion hazard. They must be stored at ambient temperatures away from ignitionsources and only in equipment or containers designed specifically for their use.Containers must be properly labelled and kept closed when not in use. Hot work,such as cutting or welding, must not be carried out on any container used for theseproducts unless it has been made safe. Containers, such as drums, containingresidues of these products must be disposed of safely according to local regula-tions.

combustible and should be stored at ambient temperature away from ignitionsources.

Fire ExtinguishingIn the event of fire, extinguish using dry powder, foam or, for small fires, carbondioxide.

The use of BCF/halon extinguishers is environmentally unacceptable. Water(as a fine spray or mist) should only be used as a protective screen and/or tocool adjacent tanks.

In some instances, products which are exposed to fire may produce toxic fumesduring thermal decomposition.

Specially Hazardous Circumstances

Aviation Fuel SpillagesIf fuel is spilled in a confined space, dangerously high concentrations of vapour areproduced; great care must be taken to reduce fire hazard and to prevent the seri-ous consequences of inhalation in such circumstances by wearing the appropriaterespiratory protection.

Aviation Fuel Tank CleaningSpecial precautions must be taken during cleaning or maintenance on storagetanks. Special precautions are also necessary when sludge from these tanks is be-ing removed or disposed of.

General Health AspectsAviation fuels (gasolines and kerosines) are complex mixtures of distillate fractionsof petroleum. They are manufactured to a technical specification and their hydro-carbon make-up varies considerably, depending on crude oil source, processingand intended application. They generally contain low concentrations of perform-ance additives.



ExposureUnder normal conditions of use, exposure to aviation fuels is likely to be confinedto inhalation of mists or vapours generated during handling or incidental skin con-tact. Accidental skin contact with methanol/water mixtures may also occur during

Emergency surgical exploration and thorough cleansing of the wound and under-lying tissue is necessary to minimise necrosis and tissue loss.

EyesEye contact with liquid products and their vapours may cause transient irritationSep04 / THTTCopyright by SR Technics Switzerland


maintenance. Inhalation exposure or accidental ingestion or eye contact is alsopossible.Exposure to lubricants and hydraulic oil is most likely to occur due to incidentalskin contact during top-up or routine maintenance procedures.

Effects of Exposure InhalationThe volatility and vapour pressure of aviation fuels and methanol/water mixturesmeans that inhalation exposure may occur to vapours and mists evolved duringhandling. Such exposure to high concentrations may cause irritation of the respi-ratory tract. In common with many hydrocarbons, exposure to high vapour concen-trations may cause drowsiness or loss of consciousness. Aviation fuels arecomplex mixtures which can contain small amounts of dangerous components. In-halation, therefore, presents a potential hazard in that this could result in absorp-tion into the bloodstream and possibly systemic damage.Under normal conditions of use, inhalation of aviation lubricants and hydraulic oilare unlikely. However, if the products are heated or used in situations where aer-osolisation is likely then exposure to mists may occur. Apart from transient irritationof the respiratory tract, such exposure is not expected to cause any particularhealth effects. Overheating of the products may, however, result in hazardous de-composition products being evolved.

SkinFrequent or prolonged skin contact with fuels and lubricants will de-fat the skin,leaving it dry and susceptible to fissuring, dermatitis and subsequent infection. Ex-posure to fuels may also cause chemical burns particularly if contact is prolongedor the affected area is occluded for example by clothing.Skin exposure to used lubricants should be avoided as they may have a potentialto cause serious irreversible skin disorders, such as warty growths and cancer,due to the presence of small amounts of harmful contaminants.Injections through the skin arising from contact with high pressure/velocity spraysare SERIOUS MEDICAL EMERGENCIES.Injuries may not appear serious at first but within a few hours tissue becomes swol-len, discoloured and extremely painful with extensive subcutaneous necrosis.

but no lasting effects. Irritant effects are likely to be more pronounced with prod-ucts of low viscosity and high aromatic content, such as some aviation gasolines.

AspirationAspiration means the introduction of liquid into the lungs. Products such as avia-tion gasolines and kerosines can enter the lung causing rapidly developing inflam-mation (chemical pneumonitis) which may prove fatal.

Preventive Measures InhalationInhalation of mists and vapours should be avoided as far as possible, and expo-sures should be reduced to the lowest practicable level. Good local and generalventilation should be provided.Appropriate personal protective equipment should be available. If operations aresuch that exposure to vapour, mist or fume may be anticipated, then suitable ap-proved respiratory equipment should be worn. The use of respiratory equipmentmust be strictly in accordance with the manufacturers instructions and any statu-tory requirements governing its selection and use.

Skin ContactSkin contact with fuels and lubricating oils of various types is a common route ofindustrial exposure. Adverse effects can be prevented by the use of good industrialand personal hygiene measures such as: the wearing of adequate protective clothing and the frequent laundering of

overalls; the provision of disposable wipes (oily rags or tools should never be kept in

overall pockets); good washing facilities should be available with hot and cold water, propri-

etary hand-cleansers and clean towels (barrier creams and reconditioningcreams may be beneficial).

Skin Care When Using Petroleum ProductsTo minimise the possibility of skin problems arising during handling fuels and lu-bricants, it is important that good hygiene (industrial and personal) practices are



followed. This section provides general advice on the prevention of occupationalskin diseases when using petroleum products. The appropriate BP Materials Safe-ty Data Sheet should be consulted for specific advice on safe handling precautionsand emergency procedures for particular Air BP products.

tact with the offending material(s) is avoided. Prevention of contact dermatitisdeveloping must, therefore, be the primary consideration.Oil Folliculitis (blocking of hair follicles) and/or Oil Acne (blocking of sebaceousand/or sweat glands) may develop as a result of prolonged skin contact with min-Sep04 / THTTCopyright by SR Technics Switzerland


Healthy SkinThe skin is the main barrier protecting the body from harmful substances in the en-vironment and comprises a thin outer layer (the epidermis) and a thicker inner lay-er (the dermis which contains sweat glands, hair follicles and blood vessels). Theepidermis consists of a layer of dead cells (cells being the basic structural andfunctional building blocks of the body) bound together by natural oils to form animpervious barrier. The natural oils present are important in retaining water andtheir loss (known as defatting) can lead to dehydration of the skin which becomesstiff and cracks open exposing the underlying living cells to harmful substances orinfection.

Effects of Petroleum Products on the SkinFrequent or prolonged contact with mineral oil products can cause various skinconditions which may occur singly or in combination:Irritant Contact Dermatitis is inflammation of the skin resulting from contact withan irritant material. The response of individuals to irritant materials may vary. Pe-troleum products, particularly those of low viscosity, may defat the skin leaving itdry and susceptible to dermatitis and infection. Irritant dermatitis is the most com-mon skin condition caused by frequent or prolonged skin contact with petroleumproducts.Allergic Contact Dermatitis occurs only in individuals who have become allergic(sensitised) to particular materials as a result of previous exposure. The inflam-mation of the skin in such cases is the same as in irritant contact dermatitis exceptthat severe inflammation may be caused by even trivial contact with small amountsof the material.In both irritant and allergic contact dermatitis, inflammation causes the skin to be-come red and itchy. Small watery blisters may develop and burst, leaving the skinsurface dry and flaky which may result in cracking and in some cases bleeding.Dermatitis developing over a long period may result in skin which is thickened andscaly. Occupational contact dermatitis commonly affects forearms, backs of handsand between fingers, but may affect any exposed areas of skin. Although it mayoccur at any age it arises most often in middle age, sometimes after exposure tothe same material for twenty years or more. Once contact dermatitis has devel-oped, the skin does not always return to a normal healthy condition even if all con-

eral oil products (particularly where oil-soaked clothing has been allowed to remainin prolonged contact with the skin). The first sign is normally the appearance ofblackheads but more susceptible individuals may suffer from boils or even car-buncles.Frequent and prolonged skin contact with some lubricants and fuels, especially ifaccompanied by poor standards of personal hygiene, may lead to localised thick-ening of the skin (keratosis) or to warty growths.Rarely, a warty growth may become malignant (cancer). In addition, small growthsor malignant ulcers may develop on otherwise normal skin. These occur most fre-quently on exposed areas (hands, forearms) but may also appear on other areaswhere the skin is habitually chafed by oil-impregnated clothing. The scrotum is par-ticularly susceptible and therefore oily rags or tools should never be put into trou-ser pockets. Work clothes should be cleaned regularly and changed promptly ifthey become contaminated. It is essential to maintain high standards of personalhygiene.Skin cancers may not appear for many years (usually more than twenty) after ex-posure. Early medical treatment is essential. Personnel with prolonged occupa-tional exposure to petroleum products should be advised by management toexamine themselves regularly, for example when bathing. Handling instructionsfor materials suspected of being able to cause skin cancer should be followedcarefully at all times. Anyone who develops a skin sore or ulcer which does notheal quickly (even though they have not handled petroleum products for manyyears) should consult a physician.

Prevention of Skin ContaminationThe best way to protect the skin from any harmful effects of petroleum products isto prevent skin contamination. Personal protection is less effective than properlyengineered containment. Work practices must be adopted to minimise contact andprevent the accumulation of material on the skin. Only disposable wipes shouldbe used workers should never put oily rags or tools in pockets.Protective clothing: cotton or polyester/cotton overalls normally provide ade-quate protection where only intermittent or occasional contact is likely. Where ahigher degree of contact is possible additional impermeable protective clothing,such as gloves, aprons, oil-resistant footwear, should be worn as appropriate.



Clothes should be changed regularly (immediately if impregnated) and launderedbefore re-use. Saturated clothing should not be allowed to chafe against the skin.Barrier Creams may help to prevent grime becoming ingrained into the skin butoffer little or no protection against harmful substances. Petroleum products shouldSep04 / THTTCopyright by SR Technics Switzerland


be washed off the skin using soap or proprietary skin cleansers and warm water.Fuels, such as gasoline or kerosine, or solvents, such as white spirit, should neverbe used as they themselves may cause dermatitis if used repeatedly. Workersshould be encouraged to wash regularly, particularly before eating. Skin cleansers(moisturising creams) may be used, for example at the end of each shift, as theycan help replace natural oils and prevent defatting.



Electrical SafetyEvery aircraft maintenance shop uses electrical power for day to day activities.While electricity performs many useful functions, you must remember that it caninjure or kill if mishandled. Consider that the aircrafts structure is conductive and

Figure 8: Electrical HazardSep04 / THTTCopyright by SR Technics Switzerland


there is always a certain amount of fuel in the tanks. On aircrafts, electrical powershould only be used to illuminate the work area. Electrical equipment such as drill-ing machines are not allowed since they produce sparks (equipped with carbonbrushes). Pneumatically actuated equipment can be used as an alternative. Gen-erally, electrical equipment must be approved and periodically checked for propercondition. When plugging elect. equipment, make sure the outlet is equipped witha fault current breaker.It is the responsibility of everyone that uses electrical power to be aware of thesafety procedures regarding it.

Extension Cords of adequate CapacityDo not use cords that are frayed, or that have any of the wires exposed, andbe sure to replace any plugs that are cracked.

The human body conducts electricity. Electrical current passing through the bodydisrupts the nervous system and causes burns at the entry and exit points. Com-mon 220/240-Volt AC house current is particularly dangerous because it affectsnerves in such a way that a person holding a current carrying wire is unable to re-lease it.Since water conducts electricity, you must avoid handling electrical equipmentwhile standing on a wet surface or wearing wet shoes. The water provides a pathto ground and heightens the possibility of electric shock.

Understand how common hand tools can create an electrical hazard.Consider a typical electric drill that has an AC motor inside a metal housing, onewire is connected to the power terminal of the motor, and the other terminal con-nects to ground. If there are only two wires in the cord and the power lead becomesshorted to the housing, the return current flows to ground through the operator'sbody.However, if the drill motor is wired with a three conductor cord, return current flowsthrough the third (yellow) wire to ground. To minimise the risk of shock, make surethat all Electrical equipment is connected with three-wire.



Compressed GasesUsage and Safety

Compressed gases are found in all aircraft maintenance shops. We use com-

New Colour Coding on Gas CylindersNew colour coding on gas cylinders have been introduced. In Figure 9 on page 13you can see the four different types of gas mainly used in the aircraft business. Theletter N indicates that the colour has become a new one. Keep in mind that theSep04 / THTTCopyright by SR Technics Switzerland


pressed air to operate pneumatic drill motors, rivet guns, paint spray guns,cleaning guns.To inflate tires, shock struts and accumulators use nitrogen only. Most shop compressed air is held in the tanks and lines under a pressure of about100 psi. If a concentrated stream of compressed air is blown across a cut in yourskin, it is possible for the air to enter your bloodstream and cause severe injury ordeath. For this reason, air dusting guns are equipped with a restrictor that reducesthe pressure at their discharge to 30 psi or less. Be very careful when using compressed air that you do not blow dirt or chips intothe face of anyone standing nearby. Always keep air hoses and fittings in goodcondition. Far too many accidents occur when inflating or deflating tires. A safety cage usedfor inflation will reduce the danger in case of a wheel failure during inflation. Alwaysuse tire gauges, and make certain to use a regulator that is in good working con-dition. High-pressure compressed gases are especially dangerous if they are mishan-dled. Oxygen and nitrogen are often found in aviation maintenance shops, storedin steel cylinders under pressure of around 3,000 psi. If a cylinder falls over andthe valve is knocked off, the escaping high-pressure gas will propel the tank like arocket. Be sure that all gas cylinders are properly supported, that the cap isscrewed securely on any tank that is not connected into a system, to protect thevalve from damage. A common method of securing high pressure cylinders in storage is by chainingthem to a wall. It is extremely important that oxygen cylinders be treated with special care. Notonly do they have all of the problems inherent with other high-pressure gases, asoxygen will cause the oil to ignite spontaneously and burn. Never use an oily rag,or tools that are oily or greasy, to install a fitting or a regulator on an oxygen cylin-der. Never use a petroleum based thread lubricant on fittings. Use only an approvedMIL Specification thread lubricant for oxygen systems.

colour coding on gas cylinder heads does not exactly describes the gas com-pound. There must be a label on the cylinder for precise differentiation. For medi-cal use, the bodies are painted white.

Figure 9: New Colour Codes for Compressed Gases

N

N

N

Colours Old New

Air

Nitrogen N

Oxygentech. &medical

O

brown

green

blue

green-yellow

intense black

pure white

NAcetylene CH orange oxide red

Type of Gas



Fire ProtectionFire protection begins with a knowledge of the types of fires, what materials areinvolved, and which extinguishing materials will work best for each type.

Requirements for FireChemically, a fire is a reaction between a material and oxygen, in which the mate-rial is reduced to its elements with the release of a great deal of heat. For example,paper is an organic material composed basically of hydrogen and carbon. When itSep04 / THTTCopyright by SR Technics Switzerland


Classification of FiresThere are different classification systems all over the world. We only discussthe system mainly used in europe and the USA.

The very nature of aircraft makes them highly susceptible to fire. They carry largeamounts of highly flammable fuel, as well as oxygen under high pressure and tocomplicate matters, smoking is allowed in many aircraft. In order to understand fires and fire protection, we should look at the classificationof fires as defined by National Fire Protection Association.

American SystemClass A fires are those in which solid combustible materials such as wood, paper,or cloth burn. Aircraft cabin fires are usually of this class. (Symbol: Green Triangle)Class B fires involve combustion liquids such as gasoline, oil, turbine fuel andmany of the paint thinners and solvents. (Symbol: Red square)Class C fires are those in which energised electrical equipment is involved. Spe-cial care must be exercised in the selection of a fire extinguisher for class C fires.(Symbol: Blue circle) Class D fires are those in which some metal, such as magnesium, is burning. Theuse of the improper type of extinguisher can intensify these fires, rather than ex-tinguish them. (Symbol: Yellow star)

European SystemClass A fires are those in which solid combustible materials such as wood, paper,or textiles burn. Aircraft cabin fires are usually of this class. Class B fires involve combustion liquids such as gasoline, oil, turbine fuel andmany of the paint thinners and solvents. Class C fires are those in which escaping gas is involved.Class D fires are those in which some metal, such as magnesium, is burning. Theuse of the improper type of extinguisher can intensify these fires, rather than ex-tinguish them.Class E fires are those in which energised electrical equipment is involved. Spe-cial care must be exercised in the selection of a fire extinguisher for Class E fires.

is heated to its kindling temperature, it will unite with the oxygen in the air and willbe changed into carbon dioxide and water. Other elements in the paper and in-complete combustion will result in a residue we know as ash, or black carbon. From the explanation, we can see that there are three requirements for fire to takeplace. We must have fuel, which is any material that will combine with oxygen; wemust have the oxygen with which the fuel can combine; and we must have somemeans of increasing the temperature of the fuel to its kindling point; the point atwhich combustion can occur. Different types of fuel have different kindling temperatures. For example, gasoline,when raised to a relatively low temperature, will combine with oxygen. Some ma-terial, such as wood, must reach a temperature considerably higher than that ofgasoline before it will ignite. The concentration of the oxygen also determines the combustibility of the material.A petroleum product, such as oil or grease, will ignite at room temperature if it isblanketed with pure oxygen.Figure 10: Fire Triangle / Three Elements of Fire

Types of Fire ExtinguishersIn order to extinguish a fire, we must either lower the temperature of the materialbelow its kindling temperature, or deprive it of oxygen. All of the fire extinguisherswe have in common use work on one or the other of these principles.

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Heat

Fuel

Oxygen



Water ExtinguishersWater can only be used for Class A fires, such as aircraft cabin fires, where elec-tricity is not involved. Most modern water-type extinguishers consist of a containerof water in which some antifreeze material has been mixed. The water is propelled

extinguishing fires in engine compartments of both piston and turbine powered air-craft. In engine compartment installations, the Halon 1301 container is pressurisedby compressed nitrogen and is discharged through spray nozzles in the enginecompartment.Table 1: Toxicity NumberSep04 / THTTCopyright by SR Technics Switzerland


from the extinguisher by a charge of carbon dioxide. Once the extinguisher is ac-tivated, all of the propellant will be discharged and a new cartridge must be in-stalled when the extinguisher is serviced.

Foam ExtinguishersFoam Extinguishers are ideal where both Class A & B fire risks exist. AFFF (Aque-ous Film Forming Foam) is particularly suited to class B fires caused by the com-bustion of materials that liquefy such as petrol, oils, fats, paints, tar etc.

Carbon Dioxide Extinguisher - COCarbon dioxide CO, is an inert gas that is contained in a steel cylinder underpressure. When the gas is released, it expands to many times its compressed vol-ume, its temperature drops, and it blankets the fire in a form of a white snow. Thecarbon dioxide gas excludes the air containing oxygen from the fire and the firedies out. CO fire extinguishers are available from the small two pound units thatmay be mounted in brackets in the cockpits of small aircraft, to the large units thatare mounted on wheels and rolled around the shop as they are needed.For this type of extinguisher to be used, the valve is opened and the CO is direct-ed at the base of the fire from a horn attached to the valve. Carbon dioxide is heav-ier than air and is electrically non-conductive. It is effective for both Class B andClass C fires. Never use CO fire extinguishers on Class D fires. The cooling effectof the carbon dioxide on the metal can cause an explosive reaction of the metal.

Halogenated Hydrocarbon ExtinguishersA halogen element is one of the group that contains chlorine, fluorine, bromine, oriodine. When some of the hydrocarbons are combined with halogens, very effec-tive fire extinguishing agents are produced. Since this extinguisher agent is veryharmful to the environment, they are only used for special aircraft applications.Halogenated hydrocarbon fire extinguishers are most effective on Class B andClass C fires, but can be used on Class A and D fires, although somewhat less ef-fective.The most popular fire extinguishing agent for cabin fires in modern aircraft isHalon 1301 (also known as Freon 13), which is most useful as a fire extin-guishment. It is not harmful to humans in concentrations as high as 203 parts byvolume. In addition to its use for cabin fires, Halon 1301 is extremely effective for

Dry-Powder ExtinguishersBicarbonate of soda, ammonium phosphate, or potassium bicarbonate are usedas dry-power extinguishants. Their main effectiveness is with Class B, -C, and -Dfires: that is, fires liquids and fires in which electrical circuits are energised. Theyare also the most effective type of an extinguishant for metal fires, such as firesinvolving burning magnesium.Dry powder is expelled from the container by compressed nitrogen and blanketsof fire, excluding oxygen from the fuel, and preventing a refresh that would re-ig-nite the fuel after it has been extinguished. Dry powder extinguishers are not rec-ommended for aircraft because of the potential damage to systems componentsfrom the loose powder, as well as the difficulty involved in cleaning the aircraft aftera dry extinguisher is discouraged.

Toxicity Group Extinguishing Agent

6 (least toxic) Halon 1301 (Bromatrifluoromethane)5a Carbon dioxin

5 Halon 1211 (Bromochlorodfluoromethane)

4 Halon 1202 (Dibromodifluoromethane)3 Halon 1011 (Bromochloromethane)

2 Halon 1001 (Methyl bromide)



Figure 11: Different Hand Fire Extinguishers Correct behaviour in case of FireThe correct behaviour in case of a fire is very important and decisive to protectpeople and material assets. Unfortunately, the fire brigade is often called to late,after an unsuccessful attempt to extinguish the fire. Valuable minutes are thereforeSep04 / THTTCopyright by SR Technics Switzerland


Figure 12: Illustrated Fire Classification

lost.The following steps explain the correct procedure:

Alarm Immediately call the Fire Brigade. You should always know the local emer-

gency numbers. They will ask you about the location, your name and the gen-eral situation.

Inform endangered persons.

Save Live Avoid panic. Save live of peoples and animals and bring them out of danger. Shut windows and doors. Leave the scene of the fire. Do not use elevators. In case of a smoky staircase or corridor, stay in the most save room with the

doors and windows closed and wait for the fire brigade.

Fight the Fire Fight the fire with available equipment such as fire extinguishers, stationary

fire extinguish equipment or fire blankets. (see Title Classification of Fires onpage 14)

Unplug burning electrical equipment before extinguishing. Pay attention to your own safety. Be always aware of the escape route.After leaving the scene of fire, you should go to an emergency meeting point andwait for further instructions.

Water or Foam Powder Carbon Dioxide CO2

BMetal

B E

Water

Foam

Powder

CO

Types of extinguisherssuitable for different classification of fire

FlammableLiquids

FlammableGas

FlammableMetals

Energized Electrical

Equipment

Wood,Paper and

Textiles

Halon

A C D



Figure 13: Fight the Fire Spilled Oil and GreaseOil, grease, and other substances spilled on hangar or shop floors should be im-mediately cleaned or covered with an absorbent material to prevent fire or person-al injury. Drip pans should be placed beneath engines and engine parts wheneverSep04 / THTTCopyright by SR Technics Switzerland


dripping exists. Waste oil and dirty cleaning fluid should be stored in containers forfuture salvage. Under no circumstances should oil or cleaning fluid be emptied intofloor drains. Fumes from this type of disposal may be ignited and cause severeproperty damage.

Aircraft Tyre MountingTo prevent possible personal injury, tyre dollies and other appropriate lifting andmounting devices should be used in mounting or removing heavy aircraft tyres.When inflating tyres on wheels equipped with locking rings, tyre cage guardsshould always be used.Where possible, all tyres should be inflated in tire cage guards. Because of possi-ble personal injury, extreme caution is required to avoid over inflation of high-pres-sure tyres. Pressure regulators should be used on high pressure air bottles toeliminate the possibility of over inflation of tyres.

Tyre cages can not be used when adjusting pressure in tyres installed on air-craft. Therefore make sure that the hose between the pressure adjusting

equipment and the tyre is long enough to stay in a safe zone while servicing thetyre.

WeldingWelding should not be performed except in designated areas. Any part to be weld-ed should be removed from the aircraft, if possible. Repair would then be accom-plished in the welding shop under controlled environment.A welding shop should be equipped with proper tables, ventilation, tool storage,and fire prevention and extinguishing equipment. Welding on an aircraft should beperformed outside if possible.

Fight the fire in direction of the wind.

Watch the scene of the fire.

In case of an extensive fire, start extinguishing from the front.

Use more than one extinguisher at the same time, if ever possible.


Module 7 Maintenance Practices7.1 Safety Precautions - Aircraft and WorkshopSep04 / THTTCopyright by SR Technics Switzerland


7.1 Safety Precautions - Aircraft and WorkshopSafety PrecautionManualsDanger SignsFigure 1: ColoursFigure 2: Signs

The Work AreaPersonal Protective Clothing and DevicesFigure 4: Protective ClothingFigure 5: Protecting Devices

Care in the use of Tools

Danger TagsFigure 6: Warning Tag

Safety with Fuels, Oils and ChemicalsFigure 7: LabelsAviation FuelsFlash Point ClassificationFire ExtinguishingSpecially Hazardous CircumstancesGeneral Health AspectsPreventive Measures InhalationSkin Care When Using Petroleum Products

Electrical SafetyExtension Cords of adequate CapacityFigure 8: Electrical Hazard

Compressed GasesUsage and SafetyNew Colour Coding on Gas CylindersFigure 9: New Colour Codes for Compressed Gases

Fire ProtectionClassification of FiresRequirements for FireTypes of Fire ExtinguishersFigure 11: Different Hand Fire ExtinguishersFigure 12: Illustrated Fire Classification

Correct behaviour in case of FireFigure 13: Fight the Fire

Spilled Oil and GreaseAircraft Tyre MountingWelding

7.01

Documents

Transcript of 7.01