Essay Mod 7.docx

8/18/2019 Essay Mod 7.docx

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Procedures of Removing Defective Solid Rivet

Rivet plays a vital role in the aircraft structure. Any defects on therivets can aect the structural integrity of the aircraft thus leading tocatastrophe damage. The following procedure explains a basic method of

rivet removal.

Always make sure the tools to be used is approved and in goodcondition. The procedure for removing defective solid rivet is laid down inthe aircraft maintenance manual (AMM.

!tart of by preparing the surface ad"acent to the defective rivet. Thisis to avoid any surface from damage caused by the defective rivetremoval procedure.

#se appropriate tools and personnel protective e$uipment. Makesure the personnel carrying out the task is well trained.

%arefully mark the centre of the manufactures solid rivet head witha centre punch. This is to mark the centre and start for drilling.

&rill the manufactured rivet head with a drill of the same diameteras the rivet shank. The rivet is drilled to the depth of the manufacturedhead.

%arefully knock o the drilled rivet head with cape chisel and prise

out the rivet head with a pin punch to fully remove the defective rivethead. Make sure not to damage or scratch the ad"acent surface of therivet.

'ith support behind the aircraft sheet metal punch out theremaining defective rivet shank with a parallel pin punch of the samediameter as the rivet shank.

%are needs to be taken during rivet removal to ensure that theleast possible damage is done to the original hole and its surroundingstructure. 'hen removing rivets from bonded assemblies it is essential

not to apply shear loads which are liable to part the bond.

Make sure to observe the utmost care should be taken when drillingand punching to ensure that the original hole is not enlarged.

All maintenance personnel should bear responsibility to properlydetect any damage on the aircraft skin. An early detection on thestructure especially on the rivets can help prevent catastrophe disaster inthe future.


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General Precautions—Working in and Around Aircraft

Aviation industry is a highly ha)ardous environment. Any mistake cancause catastrophic damage to both personnel and e$uipment. There areseveral general precautions that all personnel must observe when workingin and around aircraft.

'ear appropriate clothing. 'ear suitable footwear to avoidscratching surfaces or scu*ng anti+corrosive treatments. &o not wearfootwear with steel tips that could cause sparks. ,nsure that overalls areclean intact and properly fastened and that the pockets are sealed toprevent loose ob"ects dropping into the aircraft structure. &o not carryunnecessary loose ob"ects in pockets. &o not wear "ewellery. &o not carryany means of uncontrolled ignition such as non+safety matches or lightersin or around aircraft. ,nsure you are in the possession of approved eardefenders and are wearing these on the line when auxiliary power units ormain engines are running in the vicinity.

Aircraft must be connected to an eective earth points beforefuelling de+fuelling fuel transfer or work on oxygen systems. Reliance onthe conducting nose or tail wheels is not normally considered su*cient inthese instances. -ther systems work may re$uire that the aircraft is

connected to an eective earth and this will normally be indicated in theAircraft Maintenance Manual.

Approved re extinguishers should be located where they are easilyrecogni)ed and easily accessible. %heck that you know how to operatethem.Aircraft should be correctly chocked. Appropriate clean covers blanks andlocks are tted where necessary.

'hen operating aircraft systems on the ground you need to beaware of the eect this will have on the aircraft and any other systems

that may be activated as a result of your actions.'hen operating /ight controls ensure that their movement is notobstructed by ground e$uipment and they do not present a ha)ard toother personnel.

'hen connecting ground electrical power hydraulic or pneumaticpower to an aircraft ensure that the /ight deck controls are not set to aposition where e$uipment will be activated to move unexpectedly andpose a ha)ard to other personnel or foul ground e$uipment.


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'hen disconnecting a component or system the operation should becarried out in a controlled manner to avoid dust grit etc from entering.Approved clean blanks or caps should be used where appropriate.

Replenishment e$uipment should be kept clean and only used with

the /uid that is dedicated for. All /uid containers should be kept sealedwhen out of use and contents should not be used if contamination issuspected or the identity is in doubt.

Take care not to introduce corrosion or fatigue risks by scratchingthe aircraft paint nish or scoring the aircraft structure through carelessuse of tools and e$uipment.

,nsure that all work areas are clear of tools e$uipment and debrisbefore signing o work. &o include the surrounding /oor areas in yourchecks.

0uel and oil spillages must be cleaned up immediately. Many ofthese /uids present a re risk and also create spongy regions if theyimpregnate the rubber of aircraft tires.

,ster base oils can strip cellulose and acrylic paints and act as anirritant to human skin. %ontact with these oils is a ma"or cause ofdermatitis. 1rolonged contact can lead to more serious long+term healthproblems. 1ersonnel should make use of barrier cream wear protectiveclothing and wash aected areas on the skin.

The maintenance organi)ation should give training to the personnelin term of safety at workplace while the sta should always follow all therules. 2t is the responsibility of all personnel and organi)ation to ensurethat everyone observe the safety precautions when working in and aroundaircraft.


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Storage of Compressed Gas Cylinders

%ompressed gas cylinder is widely used in aviation industry such as3itrogen -xygen or %arbon &ioxide. These compressed gas cylinderspose serious ha)ards and potential for simultaneous exposure to bothmechanical and chemical ha)ards to the personnel and e$uipment aroundthem. 1roper procedure to handle and store compressed gas cylinder mustbe observed at all times.

4as cylinders must be secured at all times to prevent tipping.%ylinders may be attached individually to the wall placed in a holdingcage or have a non+tip base attached. %hains or sturdy straps may be

used to secure them.

%ompressed gas cylinders should be tted with transportation capsover their stop valves and be stored in unheated well+ventilated buildingsand not exposed to direct sunlight. %ylinders containing /ammable gasessuch as hydrogen or acetylene must not be stored in close proximity toopen /ames areas where electrical sparks are generated or where othersources of ignition may be present.

-xygen cylinders full or empty shall not be stored in the samevicinity as /ammable gases. The proper storage for oxygen cylinders

re$uires that a minimum of 56 feet be maintained between /ammable gascylinders and oxygen cylinders or the storage areas be separated at aminimum by a re wall ve feet high with minimum re rating of 785hour.4reasy and oily materials shall never be stored around oxygen9 nor shouldoil or grease be applied to ttings. Aviation breathing oxygen and weldingoxygen cylinders should be segregated.

%ylinders should not be placed on damp ground or exposed to anycorrosive substances or conditions. Acetylene cylinders should always bestored in an upright position. %ylinders with rounded bottoms may be

stacked hori)ontally but no more than four cylinders high and they shouldbe wedged to prevent movement.


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Refer to %ivil Aviation 1rocedure %A1 :;5 %ivil Aircraft Airworthiness2nformation and 1rocedures (%AA21


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should be at a distance from corrosive in/uences e.g. battery chargingrooms.

0ull and empty cylinders should be stored in separate rooms andappropriate notices displayed to prevent confusion.

-xygen and combustible gases such as acetylene should not bestored together.Acetylene cylinders should be stored in the upright position.

-xygen cylinders are generally rounded at the bottom therebymaking it unsafe to store in an upright position without suitable support. 2f cylinders are stacked hori)ontally special wedges should be used toprevent the cylinders rolling and the stack of cylinders should not bemore than four high.

>reathing oxygen and welding oxygen should be segregated andproperly labelled to avoid confusion. 2n some cases welding oxygen maybe used for testing oxygen components not installed in the aircraft butwelding oxygen should not be used in aircraft oxygen systems.

2f cylinders are exposed to heat the gas pressure will increase andthe cylinder walls may be weakened causing a dangerous condition.

%ylinders should be stored at some distance from sources of heat such asfurnaces stoves boilers radiators etc.

-il or grease will ignite in the presence of oxygen and if the latter isunder pressure an explosion may result. %ylinders should be kept awayfrom sources of contamination such as oil barrels overhead shaftinghydraulic components or any container or component that may contain oilor grease.

!moking exposed lights or res should not be allowed in any roomwhere compressed gases are stored and oily or greasy clothes or hands

should be avoided when handling the cylinders. 4rit dirt oil and watershould be prevented from entering the cylinder valves.

'hen returning any cylinder that may have been accidentallydamaged or overheated the supplier should be notied so that anynecessary action may be taken before relling.


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Pipe +ending

1ipes are used widely in aircraft to transfer /uid such as fuel andhydraulics. !ome of these piping needs to be bend to change direction orto pass any obstacle. There are several procedures as laid down in the%ivil Aircraft Airworthiness 2nformation and 1rocedures (%AA21.

'hen manufacturing pipes for use in aircraft systems bendingshould be carried out with the aid of a tube+bending machine. There arethe &raw >ending Machine %ompression >ending Machine and !imple?and >ending Tool.

!ome pipe materials re$uire heat treatment to soften them prior to

bending followed by further heat treatment after bending to relieve stressand restore their properties.

1rior to conducting any heat treatment the pipe should bethoroughly cleaned. The presence of carbon in oils greases anddegreasing agents can lead to serious weld decay problems in somematerials. ?igh+pressure para*n sprays may be used for initial cleaningbut this should be followed by degreasing with an appropriate solventsuch as trichloroethylene and blow+drying in warm air.

Tubing normally re$uires some form of internal support during thebending process to prevent it from /attening in the bend area.


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melting point fusible alloy is used to ll pipes prior to bending in order toprovide support when full+bore bends are being formed. This reduces therisk of fracture wrinkling and kinking. The ller can be easily removedafter bending without aecting the heat treatment state of the pipematerial. 0usible alloys have low melting point that is below 766@% and

can be melted out by immersion in boiling water.

The pipe is oiled rst before lling with ller to prevent the alloyadhering to the tube wall. 0usible alloys have a detrimental eect on hightensile steels and direct contact with them must be avoided. The pipe isthen plugged at one end pre+heated and then lled with the melted alloy.-nce cooled the pipe can then be bent as re$uired. %are needs to betaken not to create air pockets or breaking of the lubrication lm duringthe loading operation.

After bending the pipe should be unloaded by immersing it inboiling water until the entire alloy has run out. The pipe must then becleaned internally to ensure that any alloy adhering to the walls of thepipe is removed. This is accomplished by using a pull throughB with thepipe immersed in boiling water or by using a steam cleaner.

The complete removal of the fusible alloy from the pipe is extremelyimportant as its presence may lead to blockages or corrosion and in steeltubes which may be subse$uently heat+treated the presence of any alloywould cause inter+crystalline cracking.

0ollowing the correct procedure from approved manuals will ensure thelong serviceability of the manufactured pipe used in aircraft thismaintaining its airworthiness.

C"emical Corrosion Removal ,et"od -n Aluminium Alloy

%orrosion on aircraft structure can widely aect its structural integrity.

1repare the area before attempting any corrosion removal procedure bycarring out the followingC

1osition the aircraft in an area with washing facilities for rapid rinsing of allsurfaces.>ond the aircraft to the ground.Remove the battery if corrosion is in that area.%over pitot static heads static vents and engine openings. 1rotect aircraftinterior from moisture and chemicals.1rotect surfaces ad"acent to the working area from chemical paintstrippers corrosion removal agents and surface treatment materials.>efore commencing corrosion rectication reference must be made to theaircraft structural repair manual. The following notes are of a generalnature only. !A0,TD 1R,%A#T2-3!


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The following are general safety precautions which should be observedwhen handling solvents special cleaners paint strippers etchants andsurface conversion chemicalsC

>arrier cream must be rubbed on the hands before starting work.Avoid prolonged breathing of solvent or acid vapours and do not use themin conned spaces without ade$uate ventilation or approved respirator.3ever add water to acid. Always add acid to water.Always mix chemicals using the approved procedure with containerswhich will withstand heat.,nsure that a supply of clean water and eye irrigator bottles foremergency use is available in the immediate area.#se rubber or pvc gloves goggles or plastic face shields and suitableprotective clothing.2mmediately wash any harmful material from body skin or clothing.?armful materials splashed in the eyes must be immediately /ushed outwith water and medical aid obtained.&o not eat or keep food in work areas and always wash hands beforeeating or smoking.%lean all e$uipment after work has been completed.Many chemicals employed in remedial or corrosion preventativeprocedures can cause pollution if discharged into a waterway via a surfacewater drainage system. efore attempting to remove corrosion from any metal surface it must becleaned and degreased. There are a number of solvents and solvent cleaning processes used in

aircraft and component maintenance. !ome of these solvents andprocesses may have a denigrating eect on aircraft materials or pose athreat to health. Therefore the use of solvents and processes such asimmersion spraying and vapour bath cleaning etc. should be carried outstrictly in accordance with the procedure stated in the AircraftMaintenance Manual or Maintenance 1rocess !pecication. 1A23T R,M-FA<

Approved non+/ammable paint strippers should be used to remove paints.

The surrounding areas should be masked o or covered with suitableprotective material eg. polyurethane sheet. The strippers should be


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brushed over the paint left on the surface for a few minutes and thesoftened paint then removed using a non+metallic scraper. After the painthas been removed all traces of the stripper must also be removed. %hemical Methods %orrosion Removal

%hemical methods of neutralising corrosion are used mainly on aluminiumand magnesium alloys. The safety precautions details earlier for handling chemicals etc. must beobserved.'here thickened phosphoric acid (&eoxidine is approved for use onaluminium alloys the following procedure is generally used.&egrease the areaRemove paintRemove as much of the corrosion products as possible by mechanicalmethods. 0eather the edges of surrounding paint.Apply a coat of the specied thickened phosphoric acid (deoxidine bybrush to the corroded area taking care to avoid ingress to crevices or "oints. Avoid contact with ultra+high tensile steels by masking asnecessary. 0resh solution must be used for each application.Allow : to 56 minutes for the solution to act9 agitate with a sti bristlebrush where heavy corrosion is present9 9wipe o and wash the area withclean water.2f necessary repeat the above procedures.&ry all surfaces thoroughly.Apply the alocrom 7566 process and allow to dry for a minimum of two

hours then apply a primer and paint nish scheme within G= hours.&eoxidines M#!T 3-T be used on magnesium alloys. The chemicalmethod used for removing corrosion from magnesium in the sectionheaded Rectication of %orrosion on MagnesiumB

3on+&estructive Testing82nspection (3&T83&2 Techni$ues

!urface damage on aircraft metal structure can lead to catastrophic failuredue to structural fatigue if left untreated. 3on+&estructive Test (3&Tspecically dye penetrant /aw detection is a method that can be carriedout by a licensed aircraft engineer to detect surface damage on metal. There are several process in carrying out dye penetrant /aw detection.

All procedure is laid down in approved maintenance manual and%ivil Aircraft Airworthiness 2nformation and 1rocedure (%AA21 1art G


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1enetrant /aw detection may be used to detect surface+breakingdiscontinuities in any non+porous materials including ceramics metalsand plastics. 2t may also be used to detect porosity in those materials thatshould not be porous leaks in tanks and cracking of internal bores.

>rie/y the steps to be taken when performing a penetrant inspectionareC+ l. Thorough cleaning of the metal surface.5. Applying penetrant.H. Removing penetrant with remover+emulsier or cleaner.G. &rying the part.:. Applying the developer.;. 2nspecting and interpreting results.

2nterpretation of Results

7. The success and reliability of a penetrant inspection depends uponthe thoroughness with which the part was prepared.5. The penentrant must enter the defect in order to form andindication. 2t is important to allow su*cient time so the penetrant can llthe defect. The defect must be clean and free of contaminating materialsso that the penetrant is free to enter. H. The smaller the defect the longer the penetrating time. 0ine crack+like apertures re$uire a longer penetrating time than defects such aspores.

G. The si)e of the indication or accumulation of penetrant will showthe extent of the defect and the brilliance will be a measure of its depth.&eep cracks will hold more penetrant and therefore will be broader andmore brilliant. Fery ne openings can hold only small amounts ofpenetrant and therefore will appear as ne lines.

0alse 2ndications There is a condition which may create accumulations of penetrant that aresometimes confused with true cracks and discontinuities. This condition is caused by poor washing. 2f the surface penetrant is notcompletely removed during washing or rinsing operation the unremovedpenetrant will be visible. ,vidences of incomplete washing are usuallyeasy to identify since the penetrant is in broad areas rather than in thesharp patterns found with true indications. 'hen accumulations ofunwashed penetrant are found on a part the part should be completelyreprocessed. &egreasing is recommended for removal of all traces of thepenetrant.


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Advantages and disadvantages The main advantages of &12 are the speed of the test and the low cost.&isadvantages include the detection of only surface /aws skin irritationand the inspection should be on a smooth clean surface where excessivepenetrant can be removed prior to being developed. %onducting the test

on rough surfaces such+as Ias+weldedI welds will make it di*cult toremove any excessive penetrant and could result in false indications.'ater+washable penetrant should be considered here if no other option isavailable. Also on certain surfaces a great enough color contrast cannotbe achieved or the dye will stain the workpiece.

CAP 56 Civil Aircraft Air!ort"iness #nformation and Procedures$CAA#P%&ea'et .) Penetrant Dye Processes

!urface 1reparation2solate the ad"acent surface to the inspection area to avoid anycontamination. Make sure the surface protection and paint is removed. The surface of the inspection area is cleaned from grease dirt oil or anycontaminants that can aect the results by using an approved cleaningsolvent. !u*cient time should be allowed after cleaning for drying outotherwise the e*ciency of the penetrant dye may be aected.

Application of the &ye The penetrant dye can be applied to the surface by dipping spraying orbrushing depending on the si)e and type of surface to be inspected. The

surface must be dry before the dye is applied and make sure an evendistribution of the dye on the surface to be inspected.

1enetration TimeAllow some dwell timeB or penetration time for the dye to penetrateeectively into the defects usually in the range of : minutes to 7 hour thesmaller the defect the longer the time necessary. Temperatures andhumidity such as below 7:@% (;6@0 will retard the penetrant action of thedye thus the penetration time should be extended proportionately.

Removal of ,xcess &ye

Any dye remaining on the surfaces of the parts after expiry of thepenetration time should be removed as thoroughly as possible but withoutdisturbing the dye which would have found its way into any defectspresent. ,xcessive cleaning however may result in the dilution of the dyeor its complete removal from defects.

!urface &rying1rior to applying the developer it should be ensured that the surfacesofthe part under test is completely dry.

Application of the &eveloper


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The developer usually consists of a very ne absorbent white powderwhich may be applied in form of spray or dipping. Make sure to apply thedeveloper evenly as a too thin application will make it hard to observe themarks and too thick can mask out the penetrant appearing.

2nterpretation of &efectsAllow some time for the red indication to appear as a ne cack may take alonger time to appear compared to visible crack. Magnifying glass can beused to assist in detecting ne defects on the surface. Mark and identifythe defect appearing and refer to the approved manuals for its limitations.

Return back the parts where the inspection and rectication has beencarried out to its original condition and issue the certicate release toservice.

&anding Gear -leo /0tension 1ound &o!


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oleo is found low there are several steps to be taken to rectify theproblem.

&ebrief with the pilot on the condition of the landing gear shockstrut. Refer to any entries on the landing gear shock strut in the aircraft

techlog.

Make sure the landing gear ground lockpin is installed beforecarrying any task.2nspect the landing gear oleo for any damage. %heck the nitrogenpressure of the oleo strut by using the pressure gauge. %harge the oleowith approved nitrogen cart if the pressure os found low by referring tothe approved maintenance manual and the landing gear oleo servicingchart.

2nspect the landing gear shock strut oleo for any damage and leak.2f hydraulic leak is found on the oleo there might be damage on thedynamic seal of the oleo. %arry out oleo seal replacement and service thelanding gear shock strut with correct amount of oil and nitrogen gas byreferring to the approved maintenance manual.

&issimilar loading of the aircraft can cause some of the landing gearshock strut oleo to be compressed more than the other causing it toappear low. ,xtra fuel on one wing due to faulty fuel transfer valve cancause the oleo on that side of the wing to be compressed and appear lowmore than the other side.

Another cause for oleo extension low is because the inner cylinder is "ammed up with the outer cylinder caused by ingression dirt in the oleo. Torectify this "ack the aircraft and clean the inner cylinder with approved/uid.

2nspection


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Precaution !"en !orking !it" o0ygen

-xygen is used in aviation industry as breathing oxygen and gas welding.2t poses a serious ha)ard on personnel and e$uipment as it supportcombustion and mechanical ha)ard due to high pressure. There are

several precautions need to be observed when working with oxygen gas.

3ever charge an air or nitrogen system with oxygen. The mixturewill present a signicant re and explosion risk. These systems havedierent charging connectors to prevent from inadvertently doing this.3ever mix oxygen with other gases.,nsure that you are using the correct specication of oxygen. The bottlesare black with white hemispherical tops and are marked with the word-JD4,3 and the chemical symbol -5 in white lettering. The bottle alsocarries the warning B#!, 3- -2< -R 4R,A!,B in red lettering on a whitebackground. The American use green as the identifying colour for oxygenbottles.

&o not attempt to re+charge an oxygen cylinder that has been fullydischarge (empty. There is a strong possibility that it contains condensedmoisture and it will need purging by the contractor. #sed cylinder shouldhave at least :6psi of oxygen left inside to prevent ingress of air andmoisture.

,nsure that there is no moisture oil or grease on the e$uipment andtools or in the vicinity. This includes your hands and your clothing.

,nsure that clothing worn during oxygen system servicing is keptclean and dry and is only worn for that purpose. 1ersonnel should wearclean lint+free cotton gloves. Remove clothing and hang it in a wellventilated area for at least a $uarter of an hour after completing the task.-xygen will penetrate fabrics and make them highly /ammable.&o not expose oxygen to a source of sparks or re. A small re rapidlybecomes a very big one in the presence of oxygen.

'hen charging aircraft systems ensure that the area is wellventilated and that the aircraft and the charging trolley is earthed. 1lace

3- !M-K234 signs outside the aircraft. Avoid all testing of electrical orradio systems. Appropriate re extinguisher should be positioned where itcan be easily accessed.

>efore connecting hose to a charging point open the regulatingvalve slowly and allow a low /ow of oxygen out of the hose to purge it ofmoisture and air for about H6 sec. Keep the /ow on whilst connecting thehose to avoid introducing air into the system.Always open valves slowly by hand and do not attempt to force them.Keep charging rates low to prevent creating excessive heat.


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'hen charging is complete close the aircraft system charging valveand charging cylinder stop valve before releasing the charging linepressure by closing the regulator valve slowly to prevent a rapid release of pressure.

Always blank o any open ports in oxygen systems and charginghoses when these are not in use.

3ever lubricate the threads of oxygen e$uipment with oil or grease.-xygen that emits a bad smell is most certainly contaminated withmoisture. &o not use it.


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General safety precautions on aircraft to!ing

Towing is necessary to enable the aircraft to be moved without enginepower. The procedure re$uired will vary greatly dependent on the type ofaircraft to be moved.

The relevant maintenance manual will normally specify details ofthe towing arm and any limitations on the towing procedure. -n manyaircraft with nose+wheel steering it is normal practice to disconnect ordepressurise the aircraft steering system before towing.

0or large aircraft the tow bar incorporates a shock absorber system

normally a large spring to avoid snatching movements being transmittedto the aircraft structure. The tow bar also incorporates a shear pintoprevent excessive loads occurring between the tractor and noseundercarriage.

The following precautions must be observed when towing operationsare in progress. Reference must be made to the manual for specicinstructions.

7. Aircraft must not exceed walking pace while being towed (in closedarea.

5. -leo+leg and tyres must be correctly in/ated prior to moving theaircraft and su*cient brake pressure available for an emergency stop.

H. #ndercarriage down locks must be tted prior to towing.G. At night aircraft navigation lights must be -3.:. >y+pas pin or towing pin must be tted before connecting the tow bar.;. A person in+charge with all other team members in his sight.L. 1ersonnel must be stationed on the wing tip and tail to ensure

clearance round obstacles.=. There must be a competent person occupying the pilot seat to operate

the aircraft brakes in case of emergency.

. 'hen manhandling light aircraft by pushing do not push on the /yingcontrol surfaces or other delicate parts such as fabric skin. The leadingedges of the wings are normally the strongest so push the aircraftbackwards.

76. To avoid unnecessary stress to tyres and undercarriage themaximum turning angle should never be exceeded. The manufacturerBsmaximum turning angle is normally painted on the side of the aircraftnose. Try to terminate towing by leaving the aircraft in a straight line. This will prevent side loads remaining on the tyres when the aircraftcomes to a stop.

77. &o not operate the aircraft brakes while the aircraft is being towed.

Allow the tractor or tug to keep the aircraft under control.


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75. A propeller must never be used to push or pull the aircraft as theengine should always be regarded as NliveN and a propeller may kick if itis turned.

2acking Procedures 1or &anding Gear Retraction 3est

'hile the following procedures will generally ensure safe and satisfactory "acking of most aircraft precedence must always be given to theprocedures and precautions specied in the relevant Maintenance Manual.

-ne person should co+ordinate the operation and one person shouldcontrol each "acking point. -n larger aircraft a levelling station will alsoneed to be monitored and all members of the team may need to be inradio or telephone communication with the co+ordinator.

%hecks should be made on the aircraft weight its fuel state andcentre of gravity to ensure they are within the specied limits as detailedin the Maintenance Manual. The aircraft should be headed into wind (if it isin the open the main wheels chocked fore and aft the brakes releasedand the undercarriage ground locks installed.

2t is vital that the earth cable be connect to the earth point on theaircraft and it must be ensured that there is ade$uate clearance aboveevery part of the aircraft and that there is clearance for lifting cranes orother e$uipment which may be re$uired. Oacking pads should be attached to the "acking points and adaptersprovided for the "acks as re$uired. efore "acking commences the chocks must be removed and thenthe aircraft should be raised slowly and as evenly as possible. 'hilst "acking is in progress the locking collars should be continually wounddown keeping them close to the body of the "ack. 'hen the aircraft israised to the correct height the locking collar should be fully tighteneddown.


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'hen "acking is complete then supports may be placed under thewings and fuselage as indicated in the Maintenance manual.

A pillar (bottle "ack and an adapter are often used for raising asingle undercarriage for changing a single wheel. Alternatively a trolley

"ack or stirrup "ack may be used. The remaining wheels should be checkedto prevent aircraft movement and it may be specied that a tail supportbe located when raising a nose undercarriage. The "ack should be raisedonly enough to lift the unserviceable wheel clear of the ground.

#nspection on rivet 4oint on aircraft structure

>efore commencing any type of riveting "ob the operator shouldwhenever possible make a dummy runB by forming rivets in some sparepiece of metal of corresponding thickness checking the rivet allowanceand the ability to produce well+set satisfactory rivets.

'hilst in service rivets must be inspected regularly to check for anumber of faults that might have occurred such as corrosion fretting andfatigue. After the rivets have been closed they should be inspected toensure that they are tight and fully formed. Rivet heads must not be

deformed or cracked and the surrounding area should be free fromdistortion and undamaged by the riveting tools.

Rivets which are obviously not performing their function should bereplaced but replacement of rivets which are found to be only slightlybelow standard might do more harm than leaving them in positionparticularly in thin materials. >efore re"ecting such rivets the strengthre$uirements of the particular "oint and the eectiveness of the rivets in$uestion should be considered.

'hen a /ushness tolerance is specied for countersunk rivets this

is normally checked before riveting is commenced9 however the milling of solid rivet heads may sometimes be permitted after riveting to obtain auniform protrusion. 2n this case protective treatments must be re+appliedafter milling.

Type of aircraft "oint normally used is >utt "oint Ooggle "oint


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Procedure and precautions for aircraft parking 'hen an aircraft is out of service and in the open it should be securedagainst inadvertent movement and protected against adverse weatherconditions. The operations recommended in the relevant MaintenanceManual depend on the type of aircraft the length of time it will be out ofservice and the prevailing or forecast weather conditions.

0or short term parking between /ights it is usually su*cient toapply the parking brakes lock the control surfaces and chock the wheels

but in a strong wind light aircraft should be headed into the wind.


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'hen severe weather is anticipated it is recommended that coversfor cockpit canopy and wheel are tted if available. >lanks and coversshould not be left in position when the aircraft is prepared for service.!ervicing instructions should include a pre+/ight check to ensure that allcovers are removed.

2f an aircraft has to be parked overnight or for longer periods in theopen then additional precautions should be taken to guard againstingress of foreign ob"ect damage (0-& and the eects of adverseweather as followsC

7. The undercarriage ground locks must be tted.5. 1itot Tubes Psmall probes which are open to external dynamic

pressure are covered.H. !tatic vents +small holes in the fuselage which are open to external

static pressure are covered.G. ,ngine intakes are covered.:. ,ngine exhausts are covered.;. %ooling air intakes are covered.

Procedures And Precautions During Aircraft Refuelling

2nstructions regarding the responsibilities of the various personnelinvolved in fuelling procedures and these will always take precedence incon"unction with the relevant Maintenance Manual.

1articular care must be taken when fuelling aircraft so that theoperation may be accomplished in the safest possible manner. 'heneverpossible aircraft should be fuelled in the open and not in a hangar. Thiswill minimise the re risk from high concentrations of /ammable vapours.

0ire appliances should be readily available during all fuellingoperations. %arbon dioxide or foam extinguishers are recommended butif there is a perceived increased re risk then re+ghting vehicles shouldbe standing by.

'ithin the specied danger area around an aircraft being fuelledno sources of ignition or sparks should be allowed and no electrical powershould be switched on or o during the fuelling operation.

2t is vital that the correct type and grade of fuel is used for thefuelling operation. #se of a turbine fuel in a piston aircraft will certainlycause an engine malfunction or failure that could lead to loss of anaircraft. The correct type and grade of fuel is always detailed in theMaintenance Manual and marked ad"acent to the aircraftBs fuellingpoint(s.


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%are should also be exercised so as to avoid contamination of thefuel system with water or other contaminants. The fuel supply should beregularly checked for water contamination and a sample of fuel drainedo after refuelling so that a water check may be done.

2t will sometimes be necessary to lter the fuel during over+wingrefuelling particularly in dusty climates.

,lectrical bonding of the fuel system is vital during fuellingoperations as when fuel /ows through the refuelling hose staticelectricity may be generated. This may lead to potential dierences atad"acent metal parts and initiate a spark re or explosion.

To minimise this risk the following actions should be completedbefore fuelling operations commenceC

7. The aircraft should be earthed5. The refuelling tanker should be earthedH. The no))le of the fuel hose should be electrically bonded to the

fuelling point.

Precautions 3o Prevent /lectrical 1ire

The human body makes excellent conductors of electricity so it isimportant that safe work processes are adopted when using electrice$uipment. !parks from electrical e$uipment may also create re andexplosion risks when the e$uipment is used in areas containing /ammablegases or substances. 1eople are at risks of becoming over+familiar withthe use of many of the more common portable electrical power tools andoften fail to treat them with proper care.

Always check that the supply voltage is compatible with thee$uipment. ,nsure the current is switched o when connecting or

disconnecting electrical tools and e$uipment from the mains outlets andalso ensure that the tools or e$uipment are selected to o beforeswitching on the mains power to them.

Avoid handling electrical e$uipment when you are standing on wet/oors or you are wearing wet footwear. This will provide a path to earthBand completes the live circuit that you may have become part of. &o nothandle electrical e$uipment with wet hands.

Most 5G6F electrical ground e$uipment is tted with a three+core

cable that includes an earth wire. ,nsure all electrical e$uipment is


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correctly earthed. 3ever connect electrically powered hand tools tolighting sockets because they will not be earthed.

0rayed pulled and badly kinked cables or exposed wires mayproduce a situation where an exposed live conductor contacts the earth

conductor. 'hen this occurs the e$uipment body will become live andcontact with it will put you in the live circuit. !o do not use e$uipmentthat has damaged cables or cracked connectors.

,lectrical current /owing through a cable produces heat inproportion to the resistance of the cable. 2f the current being drawn by thee$uipment is higher than the rating of the cable there is a risk that thecable insulation will overheat melt or burn and the e$uipment body maybecome live as a result. Therefore never use extension leads that containcable that has too low a rating for the e$uipment. &onBt forget to unwindextension leads fully or there is very high risk that the cable insulation willmelt through overheating.

&o not overload power outlet sockets. 2solate e$uipment from thepower source before attempting to dismantle or carry out ad"ustments toe$uipment. &o not hang electrically powered e$uipment from the supplycables.

&o not leave supply cables and extension leads trailing on the /oorwhere they may be run over by e$uipment or pose a trip ha)ard topersonnel.

Report all electrical faults immediately and do not attempt to use ituntil a competent person has properly repaired it.

Always ensure that fuses or circuit breakers are of the correct valueand make sure that the faults that cause them to blow or trip are properlyinvestigated. &o not keep on replacing or re+setting circuit protectiondevices that continue to fail.

,nsure that all electrical e$uipment is inspected before use forobvious damage and that it has been re+inspected at the stipulatedintervals by a competent person.

,lectrical e$uipment should not be used in areas where there are/ammable gases or substances present unless the e$uipment isspecically cleared for use in such areas.

'hen connecting an external electrical power source to an aircraftcheck that the supply voltage fre$uency and phase are compatible withthe aircraft system. The ground supply must be switched o prior toconnection and the connector must be fully mated before the supply isswitched on.


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Precautions "andling synt"etic ester ased engine luricating oil

There is a range of oils on aircraft forC engine lubrication systems ancillarygearboxes oil lled landing gear struts and hydraulic systems.

Turbine engine lubricating oils are low viscosity synthetic ester+baseoils and are formed from a cocktail of chemical compounds that are toxic.0irst generation turbine oils are referred to as Type 7 oils. These do notmeet the operating re$uirements of modern gas turbines. Types 5 oilswere developed to withstand the higher operating temperatures of laterengines. The two types are 3-T compatible with each other and mustnever be mixed together.


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The irritant nature of turbine engine lubricating oils means that it isessential to read the safety instructions. Avoid prolonged skin contact withthese oils and must never inadvertently ingest them. 2n the short termskin contact produces &ermatitis. 2n the long term there is a risk of healthproblems occurring as a result of prolonged contact and absorption

through the skin.

,ster+base oils are hygroscopic in that they tend to absorb moisturefrom the air. 2t is important that dispensing e$uipment and oil containersare kept clean and sealed. &ispensing e$uipment should be dedicated toone oil specication and never used for anything else. -pen containers ofoil should never be used and they should be disposed of. ,ster+base oilsare also aggressive to most aircraft paint nishes. 1olyurethane paintnishes oer the best protection from them.

3ever mix Type 7 and Type 5 oils together. %heck to make sure you havethe correct specication oil. 2t is in the Aircraft Maintenance Manual andyou can also refer to the information marked close to the replenishmentpoints.

'ear protective gloves apron and face shield when handling theseoils. 'ash hands thoroughly after contact with the oil and do not smokedrink or eat until you have done this. 2f oil enters the eyes seek medicalattention.

Always use the correct dispensing e$uipment and make sure it is

clean. %lean up spillages immediately before they attack surface nishesand correct replenishment procedure is followed.

#nspection 1ollo!ing eavy &andings

A heavy or overweight landing can cause damage to the aircraft bothvisible and hidden. All damage found should be entered in the aircraftBs Technical


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-ver+stressing may occur if the aircraft is not parallel to the runwaywhen it lands or if the nose+ or tail+wheel strikes the runway before themain wheels.

!ome aircraft are provided with heavy landing indicators which give

a visual indication that specied gB forces have been exceeded.


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and turbine blades for freedom of rotation. ,xamine all cowlings forwrinkling and distortion. %heck all /uid lines lters and chip detectors.

There are numerous other checks that need to be done dependingon the damage found during the inspections. This can include engine runs

and functional checks of all the aircraft systems. !igns of some damageand distortion could be a reason to do full rigging and symmetry checks of the airframe.

#nspection 1ollo!ing &ig"tning Strikes


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surface bearings this in turn may cause burning break up or sei)ure dueto welding of the bearings.

This type of damage may result in resistance to movement of thecontrols which can be checked by doing a functional check of the

controls. Additional checks may includeC

7. ,xamine engine cowlings and engines for evidence of burning orpitting. As in control bearings tracking of the engine bearings mayhave occurred. Manufacturers may recommend checking the oillters and chip detectors for signs of contamination. This check mayneed to be repeated for a specied number of running hours afterthe occurrence.

5. ,xamine fuselage skin particularly rivets for burning or pitting.H. 2f the landing gear was extended some damage may have occurred

to the lower parts of the gear. ,xamine for signs of discharge.G. After the structural examination it will be necessary to do functional

checks of the radio radar instruments compasses electricalcircuits and /ying controls. A bonding resistance check should alsobe done.

The aircraft has all the necessary and known lightning strike

protection measures.Most of the external parts of the aircraft are metal structure with su*cientthickness to be resistant to a lightning strike. This metal assembly is itsbasic protection. The thickness of the metal surface is su*cient to protect

the internal spaces from a lightning strike. The metal skin also gives protection from the entrance of electromagneticenergy into the electrical wires of the aircraft. The metal skin does notprevent all electromagnetic energy from going into the electrical wiring9however it does keep the energy to a satisfactory level.

2f lightning strikes the aircraft then all of the aircraft must be fullyexamined to nd the areas of the lightning strike entrance and exitpoints.'hen looking at the areas of entrance and exit this structure should becarefully examined to nd all of the damage that has occurred.


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or de+laminated skin plies. ?idden damage can also exist. This damagecan extend around the visible area. !igns of arcing and burning can alsooccur around the attachments to the supporting structure.Aircraft components made of ferromagnetic material may becomestrongly magnetised when sub"ected to large currents.


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&o an operational test of the trailing edge /aps if there are signs oflightning strike damage to the trailing edge /aps. &o an operational test of the leading edge /ap8slats if there are signs oflightning strike damage to the trailing edge /ap8slats. 2f there are signs of strike damage to the landing gear doors disengage

the main gear door locks and manually move the doors to ensure theymove smoothly. Fisually examine the door linkage hinges bearings andbonding "umpers for strike damage. ,nsure the proximity switch indicationunit gives the correct indication. ,xamination of 2nternal %omponents2f a lightning strike has caused a system malfunction do a fullexamination of the system. &o a check of the stand+by compass system if the /ight crew reported avery large compass deviation. Make sure the fuel $uantity system is accurate. This can be achieved bya >2T, test. ,xamine the air data sensors for signs of strike damage. &o anoperational test of the pitot system if there are signs of damage to theprobes. &o a test of the static system if there are signs of damage nearthe static ports. &o an operational check of any of the following systems that did notoperate following the strike or if the /ight crew reported a problem or ifthere was any damage found near the system antennaCS ?0 communications systemS F?0 communications system

S 2


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usually be in the form of small circular holes usually in clusters andaccompanied by burning or discoloration. !tatic discharge damage at the wing tips trailing edges and antenna. The damage will be in the form of local pitting and burning. >onding stripsand static wicks may also disintegrate due to the high charges.

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