M7 Maintenance Practices essay (CAT A1)
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The document provides information on various aircraft maintenance procedures and tasks. It discusses rivet replacement, component life control, additional maintenance like washing and painting, quality control inspections, interfacing maintenance with operations, certification and release procedures, storage procedures, modification processes, maintenance planning, abnormal events like heavy landings and lightning strikes, inspection procedures, corrosion control, jacking, towing, taxiing, and aircraft storage. The document serves as a reference for approved technicians to properly perform maintenance in accordance with regulations.
M7 Maintenance Practices essay (CAT A1)
- 1. Module 7 Essay 1.Rivet replace Centre punch on rivet head Drill the rivet head. Use twist drill slightly smaller diameter as rivet shank Remove rivet head use flat chisel or prised out with pin punch Push rivet shank with pin punch with same diameter Ensure least possible damage done to the original hole and its surrounding structure Use a same rivet diameter or bigger if the hole is damage for riveting a new one Use riveting tool 2.Control of life component Life = flying hours, cycles, calendar time, operating hours Correct terminology life is mandatory life limitation. specific length of time in service Technical control/records department monitor all aircraft document and control component replacement on completion of their lives Installed serviced life must not exceed approved service life limit specified in Approved maintenance Programme and Airworthiness Directive If reached, certified life limit or non-repairable defect, shall classified as unsalvageable and not permit to enter component supply system. unless Certified life limit Extended or Repair solution approved Each life component have log card while in Quarantine / bonded store. When installed, log card used in aircraft record.
- 2. 3.Additional Maintenance Procedures Apart from regular maintenance check (MM) there are number of additional maintenance done at irregular intervals o Wash aircraft o De-icing (winter) o Weighing (after certain operation) o Painting Other is o on-going sampling programme o condition monitoring That organized by local CAA office, to comply with airworthiness request from manufacturer 4.Maintenance inspection/ Quality control and assurance Each approved organisation must be monitored their procedures to determine their effectiveness and implement appropriate corrective action. QA=control standard of company QC=continuing analysis and surveillance (AUDIT) EASA Part 145 Quality System All maintenance from pre-departure check to Heavy check D inspection controlled from Maintenance schedule produced by Aircraft manufacturer Light aircraft, maintenance schedule is named Light Aircraft Maintenance Scheduled (LAMS) produced by CAA Maintenance done by approved personnel by CAA or approved by their company(approved CAA) Duplicate inspection needed when it may lead to catastrophic consequences. 5. Interface with aircraft operation link between aircraft maintenance and flying done For larger commercial companies all legislation listed in JAR-OPS by JAA where they obtained their Air operators Certificate JAR-OPS control o how company maintain their aircraft o the documentation o publication record all the info for engineer/ flight crew
- 3. o quality of whole operation on acceptable standard Communication of information between maintenance and flying personnel use o Tech log Flight time, defect, fuel and ground maintenance/replenishment o Log book (aircraft, engine and propeller) Kept within record department. Long term record= total flying hour, engine/prop life, maint. Check on aircraft o Modification record Changed made to aircraft. Refer for different maintenance/ flight operation procedures. o Minimum Equipment List (MEL) Aircraft can be operate with particular equipment inoperative o Configuration Deviation List(CDL) Missing of part and aircraft can be operate 6.Certification/release procedures Any COA aircraft must be certified by approved technician. o Personal certification o Approved by company Need Certificate of Airworthiness (COA) for aircraft to fly Certificate Release To Service (CRS) issued before flight and completion of any maintenance by approved engineer. CRS certifies that the work been done accordance with JAR 145 and aircraft is fit for release back to service 7. Stored procedure All maintenance establishment need Store department purpose: o Ensure all material, parts and component used on aircraft are to the correct specification. o Easily for component to be traced back to its original manufacture and its raw material
- 4. Approved store is approved by CAA. there are 3 main department o Quarantine store= accept item from other companies and check that they are satisfactory o Bonded Store = take item from quarantine store after approval and when requested, issues those component to servicing technician o Office / administration centre = Keep files and record for cross checking of any transaction through store system 8.Modification procedures Modification are changed made to aircraft which CAA agree and accordance with JAR OPS Medication must be approved by CAA or approved organization carrying out modification programme Must be classified as minor or major modification MAJOR = organization send AD282 to CAA . when approved, approval note send to organization MINOR= organization write to caa requesting modification . when approved, CAA send AD261 form o If organization approved by CAA, can approve its own modification and keep record in aircraft documentation 9.Maintenance planning A maintenance schedule tell the operator and maintenance organization what and when thing have to be done on aircraft. The period of maintenance can be small or large depending on type of aircraft Maintenance programme contain a list of the most significant items and recommendation as to the maintenance action Type Abnormal event Heavy landing Lightning strike Flight in turbulence Tyre burst Mercury spillage Engine seizure
- 5. 10.Heavy landing Landing gear designed to withstand particular aircraft weight and rate of descend. If exceed the parameter, caused damaged to landing gear,structure and airframe. Primary damaged occur to around the landing gear. Which is supporting structures in the wing or fuselage, wing and tailplane attachment and engine mounting. Secondary damage may found on upper and lower fuselage skin and on wing skin and structure. Questioned flight crew o Aircraft weight o Fuel distribution o Landing condition o Unusual noises Post heavy landing Inspection Landing Gear Tyre=creep,damage,cut Wheel & brake= crack or other damage Shock strut = leak, scoring and abnormal extension Gear attachment = crack, damage, movement Structure = vicinity of gear attachment point Door and fairing = Damage Test retraction and steering Mainplane /wing Upper/ lower skin = wrinkles & pulled rivet Fuel leak Root attachment = crack Flying control = function and freedom of movement Check wing spar
- 6. Fuselage Skin = damage & wrinkles Pressure bulkhead Check supporting structure of heavy component (galley, batteries,water tank & APU) Instrument and panel functional Pipes and ducts for security Door and panel fit correctly Engines Check controls for freedom of movement. mountings and pylons = damage and distortion. turbine engines = freedom of rotation. cowlings = wrinkling and distortion. fluid lines, filters and chip detectors. propeller = check for shock-loading, propeller attachments and counterweight installations. Tail Unit flying controls = freedom of movement. hinges = distortion or cracks attachments, fairings and mountings of screw jacks. May need Engine run Aircraft system functional check Rigging and symmetry check 11. Turbulance Damage may occur same as Heavy landing. It is possible that damage can occur on wing,fuselage, tail unit & flying control where greatest bending forces take place Check can be done same as heavy landing
- 7. 12.Lightning Strike Is a discharge of electricity in atmosphere. If hit aircraft, result high voltages and currents passing through the structure All aircraft part need to be bonded together to provide low resistance path to conduct electricity away to prevent damage to aircraft Effect, on Strike damage and Static Discharge damage refer AMM for more information on damaged and inspection. Strike damage o Wing tip o Wing & tail Leading edge o Fuselage nose Static Discharge damage o Wing tip o Trailing edge o Antennae External component o Nose radome o Nacelles o Elevator o Landing gear o Water and waste drain mast o Pitot probe 13. Lightning strike Inspection static discharge damage bonding strips and discharge wicks = burning and disintegration Engine cowl = burning / pitting Fuselage skin rivet = burning / pitting functional check on control system= freedom of movement o radio & radar equipment o Instruments o Compasses o Electrical circuit
- 8. 14. Basic Protection against lightning strike External Surface o The thickness of the metal surface is sufficient to protect the internal spaces from a lightning strike o protection from the entrance of electromagnetic energy into the electrical wires of the aircraft 15. SIGN of lightning strike METAL pits burn mark small circular holes discolored skin Composite burned punctured de-laminated skin plies Aircraft Component (Ferromagneticmaterial) caused magnetization Electrical Component lightning strike hit static discharge wick caused damage or unserviceable if static charge not discharge from aircraft caused disturbance or ‘noise’ in radio
- 9. 16. Examine external surface, functional test, internal component find entrance and exit point look for sign on metal / composite structure use NDT on composite to detect non visible damage 17. High Intensity Radiated Fields (HIRF) electromagnetic interference HIRF environment area o Aircraft structure o Electrical Wiring installation Protection (solid/braided shielding connectors) o Equipment Protection (LRU case) Test HIRF use milliohm meter measure resistance of bonding Protect against HIRF interference o Bonding of aircraft o Correct crimping o Bonding terminal correctly torque loaded 18. Type Of defect Metal Cleanliness and external evidence of damage Leaks and discharge Overheating Fluid ingress Obstruction of drainage Correct seating of panels and fairings and serviceability of fasteners Distortion, dents, scores, and chafing Pulled or missing fasteners, rivets, bolts or screws Evidence of cracks or wear Failures of welds or spot welds Security of attachments, fasteners, connections, locking and bonding.
- 10. Rubber, Fabric, Glass Fibre and Plastic Parts Cleanliness Cracks, cuts, chafing, kinking, twisting, crushing Deterioration, crazing, loss of flexibility Overheating Fluid soakage Security of attachment, correct connections and locking. corrosion control Adequate and regular cleaning of the aircraft Periodic lubrication (often after the cleaning) of moving parts Regular and detailed inspection for corrosion and failure of protective treatments Prompt treatment of corrosion and touch-up of damaged paint Keeping of drain holes clear Draining of fuel cell sumps Daily wiping down of most critical areas Sealing of aircraft during foul weather and ventilation on sunny days Use of protective covers and blanks. Corrosion Removal Cleaning and stripping of the protective coating in the corroded area. Removal of as much of the corrosion products as possible. Neutralisation of the remaining residue. Checking if damage is within limits Restoration of protective surface films Application of temporary or permanent coatings or paint finishes. Ferrous metal Mechanically remove by abrasive paper, power buffer, wire brush and steel wool
- 11. Acid / alkali spillage Mop up as much of the spilled acid using wet rags or paper wipes. Try not to spread the acid. If possible, flood the area with large quantities of clean water, taking care that electrical equipment is suitably protected from the water. If flooding is not practical, neutralise the area with a 10% (by weight) solution of bicarbonate of soda (sodium bicarbonate) Alkaline or 5% by weight chromic acid with water. Wash the area using this mixture and rinse with cold water. Test the area, using universal indicating paper (or litmus paper),to check if acid has been cleaned up. Dry the area completely and examine the area for signs of damaged Remove corrosion, repair damage and restore surface protection as appropriate Cleaning and Paint Removal Use water-removeable stripper Adequate ventilation Protect all synthehtic, rubber part Proper PPE rubber glove, acid repellant apron and google Mask the vulnerable area Brush the area with stripper, to a depth of approximately 0.8 mm - 1.6 mm. Ensure that the brush is only used for paint stripping. Allow stripper to remain on the surface long enough for the paint to wrinkle. This may take from 10 minutes to several hours. Re-apply the stripper to those areas which have not stripped. Non-metallic scrapers may be used. Remove the loosened paint and residual stripper by washing and scrubbing the surface with water and a broom or brush. Water spray may assist, or the use of steam cleaning equipment may be necessary.
- 12. Disassembly and Re-assembly Techniques In event of o Complete airframe disassembly for shipment o Replacement of major components/modules (large maintenance base) o Replacement of minor components/modules (repair bay) o Disassembly & re-assembly of major components o Disassembly & re-assembly of minor components Instruction can found in AMM/ Special dismantling procedure by manufacturer Precaution o dismantled within a hangar. If not possible, level and firm ground will suffice o Sufficient clearance in the hangar for airframe when on jacks allow heavy lifting cranes enough room to manoeuvre over the aircraft o All precautions, in accordance with the manufacturer's instructions, must be taken o When the aircraft is jacked-up, all trestles must also be placed in position and ensures that it will not overbalance when a major part (such as a wing), is removed Order of disassembly o Main plane (wing) o Tail o Undercarriage o Centre o fuselage
- 13. 19. Towing moving aircraft without pilot need tug and towing arm when towing using hand, use proper handling procedure do not push at o control surface o propeller use tow bar to move and steering the aircraft attached to wheel axle do not lock rudder control system do not exceed steering limit marked on nose gear door. Or can disconnect torque link and other attachment person o Qualified tug driver o Supervisor o Brake man , do not try to steer the aircraft, check brake systemand accumulator o Lookout for clearance o Radio to communicate with crew Clearance for towing Speed must be below 5mph All door closed Safety precaution and procedures based on AMM 20. Taxiing Qualified person to do taxiing Check clearance from people or equipment before start engine View from cockpit is limited, need signalman or marshaller to check for any obstruction Make sure marshaller can be view from the cockpit Receive clearance from ground control before taxiing Once aircraft in motion, make sure brake and steering is operate
- 14. 21. Jacking For weighing,maintenance or repair Refer safety procedures and precaution in AMM Check clearance and leveling 1 or 2 person at each jack If jack outside, aircraft nose to wind Jacking surface strong and level Brakes at off position Choke installed, when jacking commence, remove chock When remove wheel or brake, can jack at 1 point only o Attach at jack point that approved my manufacturer only Use proper and serviceable jack and leveling equipment to prevent aircraft move sideway or tilt Attach at proper jack pad refer from AMM Position jack properly at jacking point to prevent slipping Safety collar must be screwed down to prevent collapse or lock pin must be place at lowest position as aircraft raised As aircraft raised, the cg may be forward or backward. Attach ballast or check the fuel load to bring COG to safe limit When jacking complete, install support (tresle) under wing and fuselage Lowering Ensure brake off by rotate the wheel Clearance Lowered jack together straight and level Remove jack pad and adapter Install chock
- 15. 22.Aircraft storage Protect against to deactivated aircraft for an extended time (30 days to 2 years) o corrosion o deterioration o environment condition during storage Refer MM ATA chapter 10 : parking and mooring Chock aircraft Rotate tyre to prevet flat spot every 30 days Change to dummy tyre (not suitable for flight) Tank filled with water Toilet drained Fuel tank part fill Propeller feathered and strap Circulate by open internal door but closed external door and panel Battery removed and store in battery bay Greased or lubricate Blank and cover the hole, pitot and engine intake Perform weekly check or 2 week check such as o Run engine o Reinstall battery o Perform functional test Refuelling/defueling Use of the wrong type, wrong grade, intermixed, or contaminated fuels can lead to engine failure and catastrophe Bonding aircraft to ground, aircraft to fuel truck, fuel truck to ground minimize static electricity because 3 factor caused fire. Fuel, oxygen and heat So use correct procedure and ensure clean supply of fuel Trained personnel in handling fuel. Don’t do in enclosed space (hangar) 2 method, gravity and pressure Check fuel contamination (water, solid, microbial growth, intermixing of fuel) Do not punctured the fuel tank when performing gravity refuelling
- 16. Fuel spilled, wiped or washed away with water ASAP. Don’t swept with broom, static electricity can ignite the vapour Stored fuel in approved container, kept close, cool and isolated area in approved fuel storage 2 method defueling, Gravity and pressure. Pressure use bowser to draws the fuel from the suction point Deicing/ anti-icing procedure Remove ice before flight because it can affect aircraft performance o Decreased aerofoil lift o Increased aerofoil drag o Increased weight o Decreased engine thrust o Freezing of moisture in control hinges o Freezing of micro-switches that affect systems such as the landing gear retraction o Ingestion of ice into the engine. Before aircraft begin take-off, clear the aircraft from ice on critical area o Pitot tubes & heads o Temperature probes o Static ports o Ram air intakes for engine control and flight instruments o Engine inlets o Wings & Tail section o Flight control surface It used fluid that contain Freezing Point Depressant (FPD) which are very soluble in water
- 17. DE-ICING Before spray deice fluid. Remove the snow first using broom or squeegees o Ensure no sharp edge or FOD that can damage aircraft o Push from LE to TE For engine intake, remove by hand with clean brush or gloves Inspect after deicing or anti-icing Make entry on tech log for completion of deicing procedure Hoisting Mooring Picketing