Overhauling aircraft piston engines
Overview
This standard identifies the competences you need to carry out a complete overhaul of aircraft piston engines, in accordance with approved procedures. The engine to be overhauled will have been removed from the aircraft and the overhauling activities may take place in a workshop or hangar.
In carrying out the overhauling operations, you will be required to follow laid-down procedures and use specific dismantling and rebuilding techniques. The overhauling activities will involve removing the engine nacelles/outer casing, removing all ancillary equipment and components and dismantling the engine down to the various sub-assembly units, such as cylinder block and cylinder heads. You will be expected to strip the various sub-assemblies down to their component parts. You will then rebuild the engine, which will involve fitting replacement or overhauled sub-assembly units (such as cylinder block, cylinder heads, torque converters, oil pumps) and the replacement of all damaged, worn and `lifed' components. The overhauling activities will include making all necessary checks and adjustments to ensure that components are correctly replaced, positioned, aligned, adjusted, torque loaded, locked and fastened, and that the correct sealants are used.
Your responsibilities will require you to comply with organisational policy and procedures for the overhauling of the aircraft piston engine, and to report any problems with the overhauling activities, or with the tools and equipment used that you cannot personally resolve or that is outside your permitted authority, to the relevant people. You must ensure that all tools, equipment and materials used in the overhauling activities are removed from the work area on completion of the activities, and that all necessary job/task documentation is completed accurately and legibly. You will be expected to work with a minimum of supervision, taking personal responsibility for your actions and for the quality and accuracy of the work that you carry out.
Your underpinning knowledge will provide a good understanding of your work and will provide an informed approach to applying appropriate overhauling techniques and procedures to aircraft piston engines. You will understand the dismantling and reassembly methods and procedures used, and their application. You will know how the engine functions, the purpose of the individual components and associated defects, in adequate depth to provide a sound basis for carrying out the overhauling activities to the required specification. In addition, you will have sufficient knowledge of these components, to ensure that they are fit for purpose and meet the specifications, thus providing a sound basis for carrying out the reassembly.
You will understand the safety precautions required when carrying out the overhauling activities associated with aircraft piston engines, especially those for lifting, handling and supporting the equipment being removed and replaced. You will be required to demonstrate safe working practices throughout and will understand your responsibility for taking the necessary safeguards to protect yourself and others in the workplace.
Performance criteria
You must be able to:
- work safely at all times, complying with health and safety and other relevant regulations, directives and guidelines
- follow the relevant overhauling schedules to carry out the required work
- establish the components to be removed and where appropriate, mark components to aid re-assembly
- ensure that any stored energy or substances are released safely and correctly
- carry out the overhaul to the agreed level, using the correct tools and techniques
- ensure that all removed components are correctly identified and stored in the correct location
- replace/refit components using appropriate methods and techniques
- carry out checks on the overhauled engine using correct procedures
report any instances where the overhauling activities cannot be fully met, or where there are identified defects outside the planned overhauling schedule
complete the relevant documentation, in accordance with organisational requirements
- dispose of unwanted components, waste materials and substances, in accordance with safe working practices and approved procedures
- deal promptly and effectively with problems within your control and report those that cannot be solved
- leave the engine in a safe and appropriate condition, free from foreign object debris and in a condition ready for testing
Knowledge and Understanding
You need to know and understand:
- the specific safety practices and procedures that you need to observe when overhauling aircraft piston engines (including any specific legislation, regulations/codes of practice for the activities, equipment or materials)
- the health and safety requirements of the area in which the overhauling activity is to take place, and the responsibility these requirements place on you
- the hazards associated with overhauling aircraft piston engines (such as such as handling oils, greases, aviation fuel, stored pressure/force, use of power tools, misuse of tools, using damaged or badly maintained tools and equipment, not following laid-down overhauling procedures, lifting and moving large and heavy components) and how to minimise them and reduce any risks
- the requirements and importance of understanding and applying human factors as defined by the regulatory requirements and the potential impact if these are not adhered to
- the importance of wearing protective clothing and other appropriate safety equipment (PPE) during the overhaul
- how to obtain and interpret drawings, specifications, manufacturers' manuals, history/maintenance reports and other documents needed in the overhauling process
- how to carry out currency/issue checks on the specifications you are working with
- the quality control procedures to be followed during the overhauling operations
- the procedure for obtaining replacement parts, materials and other consumables necessary for the overhaul
- company policy on the repair/replacement of components during the overhauling process
- terminology used in aircraft piston engines and engine modules
- the principles of how the engine functions, its operating sequence, the working purpose of individual units/components and how they interact
- the extent to which the equipment is to be dismantled for overhaul
- the sequence to be adopted for the dismantling/reassembling of various types of engine assemblies
- the techniques used to dismantle the aircraft piston engines, without damage to the components or surrounding structure (such as release of energy/pressures/force, draining of fluids, making electrical disconnections, proof marking components to aid reassembly, removing assemblies requiring pressure/force, removing mechanical locking and
securing mechanisms/devices) - the need to protect the system integrity by ensuring that exposed components are correctly covered/protected
- how to lift and move large components and assemblies; the methods and equipment used to transport, handle and lift the components during the overhauling activities
- the need to ensure that lifting and handling equipment is within its current certification dates
- methods of checking that components are fit for purpose, how to identify defects and wear characteristics, and the need to replace `lifed' items (such as seals and gaskets)
- the uses of measuring equipment (such as micrometers, verniers, expansion indicators and other measuring devices)
- methods of reassembling the aircraft piston engine, using new or previously overhauled subassemblies (such as replacing assemblies requiring pressure/force, ensuring correct orientation and location of subassemblies, replacing mechanical locking and securing mechanisms/devices, reconnecting pipes and electrical connectors)
- how to make adjustments to replaced components/assemblies to ensure that they function correctly (such as checking alignment, balancing of rotating components such as flywheels and torque converters, setting working clearance, setting travel, and pre-loading bearings)
- the various mechanical fasteners that are used and their method of removal and replacement (including rivets, threaded fasteners, special securing devices)
- the various types of electrical connector that are used, methods of unlocking, orientation indicators and locating and locking in of the connections
- why electrical bonding is critical and why it must be both mechanically and electrically secure
- the tools and equipment used in the overhauling activities and how to check that they are in a safe, tested and usable condition
- the importance of ensuring that all tools are used correctly and within their permitted operating range
- the importance of ensuring that all tools, equipment and components are accounted for and returned to their correct location on completion of the overhauling activities
- the procedure for the safe disposal of waste materials
- the generation of maintenance documentation and/or reports following the overhauling activity
- the problems that can occur during the overhauling activity and how they can be overcome
- the extent of your own authority and to whom you should report if you have a problem that you cannot resolve
Scope/range
Scope Performance
Carry out all of the following during the overhaul of the aircraft piston engine:
- obtain and use the appropriate documentation (such as job instructions, engine overhauling manuals, engineering drawings, technical instructions, and other relevant maintenance documentation)
- adhere to procedures or systems in place for risk assessment, COSHH, personal protective equipment and other relevant safety regulations and procedures to realise a safe system of work
- provide and maintain safe access and working arrangements for the overhauling area
- obtain the correct tools and equipment for the activity and check that they are in a safe, tested and usable condition and within current certification/calibration date
- ensure that all oils, fluids and fuel have been drained/removed before breaking into the system
- ensure that the piston engine assembly is suitably supported, and that appropriate lifting and handling equipment is available
- carry out the overhauling activities, using approved techniques and procedures at all times
- ensure that components and surrounding structures are maintained free from damage and foreign objects
- return all tools and equipment to the correct location on completion of the activities
Carry out a major overhaul of one of the following types of aircraft piston engine:
- in line engine
- 'vee' engine
- rotary engine
Dismantle aircraft piston engines, to include removing ten of the following:
- cylinder head
- piston assemblies
- valve mechanisms
- carburettor systems
- crank shaft
- cylinder liners
- oil pumps
- manifolds and exhaust systems
- flywheel
- camshaft assemblies
- fuel/injector pumps and mechanisms
- gearbox
- timing mechanisms
- turbo/supercharger
- torque converter
Carry out all of the following activities on the equipment being overhauled:
- pre-disassembly checks
- re-assembling components to sub-assembly level
- removing engine nacelles/outer casing
- disconnecting and removing wires/cables and attaching suitable cable identification markers
- re-assembling sub-assemblies to unit level
- setting and adjusting replaced components
- removing all ancillary components
- disconnecting and removing pipework
- using specialist tooling
- dismantling equipment to unit/sub-assembly level
- making use of ground support equipment
- dismantling units to component level
- supporting the equipment to be removed
- proof-marking/labelling of components to aid reassembly
- electrical bonding of components
- checking components for wear and serviceability
- replacing all damaged or defective components
- applying gaskets and sealant/adhesives
- replacing all 'lifed' items (such as seals, bearings, gaskets)
- tightening fastenings to the required torque
- securing components using mechanical fasteners and threaded devices
- applying bolt locking methods (such as split pins, wire locking, lock nuts, stiff nuts, swage nuts)
Replace a range of piston engine components, to include twelve of the following:
- cylinder head
- camshaft assemblies
- fuel pumps
- manifolds
- crank shaft
- timing mechanisms
- seals and gaskets
- sump pans
- flywheel
- valve mechanisms
- pulleys and sprockets
- exhaust systems
- torque converters
- oil pumps
- belts and chains
- pipes and unions
- cylinder liners
- bearings
- levers and linkages
- turbo/supercharger
- piston assemblies
- injector mechanisms
- sensing devices
- other specific component
Carry out checks and tests on the overhauled equipment, to include seven of the following:
- positional accuracy
- timing (such as valve, ignition fuel injection)
- orientation
- operating/working clearance
- alignment
- visual inspection for completeness and freedom from damage or foreign objects
- freedom of movement
- bearing end float
- boost pressure
- gear backlash
- 'special-to-type' test rig checks
- compression
Overhaul aircraft piston engines in compliance with one of the following:
- Civil Aviation Authority (CAA)/European Aviation Safety Agency (EASA)
- Federal Aviation Authority (FAA)
- Military Aviation Authority (MAA)
- Aerospace Quality Management Standards (AS)
- BS, ISO or BSEN standards and procedures
- customer standards and requirements
- company standards and procedures
- engine manufacturer's requirements
Complete the relevant paperwork, to include one of the following and pass it to the appropriate people:
- job cards
- computer records
- aircraft log books
- engine overhaul logs or reports
- work authorisation documents
- permit to work/formal risk assessment
Scope Knowledge
Values
Behaviours
You will be able to apply the appropriate behaviours required in the workplace to meet the job profile and overall company objectives, such as:
- strong work ethic
- positive attitude
- team player
- dependability
- responsibility
- honesty
- integrity
- motivation
- commitment