Overhauling components of aircraft hydraulic equipment
Overview
This standard identifies the competences you need to carry out overhauling activities on aircraft hydraulic equipment and components, in accordance with approved procedures. The equipment to be overhauled will have been removed from the aircraft and the overhauling activities may take place in a workshop or hangar.
It covers both fixed wing and rotary winged aircraft, and covers a range of hydraulic equipment such as landing gear, nose wheel steering, wheel braking systems, flying controls, rotor brakes, arrestor mechanisms, and other aircraft specific equipment. The overhauling activities will include carrying out all necessary safety checks, dismantling the equipment to unit or component level, inspecting and checking all components for damage and wear, replacing all 'lifed' items and worn/faulty components or units, reassembling the equipment and carrying out all necessary tests/checks.
Your responsibilities will require you to comply with organisational policy and procedures for the overhauling activities undertaken, and to report any problems with the overhaul 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, 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 own 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 procedures to aircraft hydraulic equipment. You will understand the dismantling and reassembly methods and procedures used, and their application. You will know how the equipment functions, the common faults encountered, the purpose of the individual components and associated defects, in adequate depth to provide a sound basis for carrying out the overhauling activities, correcting faults and ensuring that the overhauled equipment meets the required specification.
You will understand the safety precautions required when carrying out the overhauling activities, especially those for handling hydraulic fluids. 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 overhaulingschedules to carry out the required work
- carry out the overhauling activities within the limits of your personal authority
- carry out the overhauling activities in the specified sequence and in an agreed timescale
- replace/refit components using appropriate methods and techniques
- carry out checks on the overhauled equipment using correct procedures
report any instances where the overhaulingactivities cannot be fully met or where there are identified defects outside the planned schedule
complete the relevant documentation, n accordance with organisational requirements
dispose of waste materials in accordance with safe working practices and approved procedures
- leave the equipment in a safe and appropriate condition, free from foreign object debris
Knowledge and Understanding
You need to know and understand:
- the safe working practices and procedures and the specific safety precautions to be taken when overhauling aircraft hydraulic equipment (to include wearing protective clothing and equipment; lifting and handling techniques; safe working practices and procedures with regard to working on aircraft hydraulic equipment and when using synthetic oils; procedures and guidelines which satisfy current regulations such as HASAWA, COSHH and other work related legislation and guidelines)
- hazards associated with carrying out overhauling activities on aircraft hydraulic equipment (such as using lifting and handling equipment, handling hydraulic oils, releasing stored pressure/fluids, misuse of tools, using damaged or badly maintained tools and equipment, not following laid-down overhauling procedures) 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 extract and use information from aircraft manuals, history/maintenance reports, aircraft logs, charts, circuit and physical layouts, specifications, symbols used in aircraft hydraulic systems, and other documents needed in the overhauling process
- how to carry out currency/issue checks on the specifications you are working with
- the procedure for obtaining replacement parts, materials and other consumables necessary for the overhaul
- terminology used in aircraft hydraulic systems and the use of fluid power diagrams and associated symbols
- the various types of components that make up the aircraft hydraulic equipment (such as pipes; flexible hoses; valves used for pressure, flow and directional control; double and single action cylinders/actuators; pumps; pressure intensifiers, mechanical and electrical control devices)
- the principles of operation of the hydraulic equipment being worked on, and the performance characteristics and function of the valves, cylinders/actuators within the circuit
- the sequence to be adopted for the dismantling/reassembling of various types of hydraulic assembly
- the techniques used to dismantle the equipment to unit or component level, without damage to the components (such as release of pressures/force, draining of fluids, proof marking/labelling removed components, extraction of components and the need to protect the circuit integrity by fitting blanking plugs/covers)
- the identification and application of different types of valve, sensor and actuator (such as rotary, linear, mechanical, electrical); cylinders (such as single acting, double acting); pumps (such as positive and non-positive displacement); static and dynamic seals
- the various mechanical fasteners to be removed and replaced, and their method of removal and replacement (such as threaded fasteners, special securing devices)
- methods of lifting, handling and supporting the components/equipment during the removal and replacement activities
- recognition of contaminants and the problems they can create; the effects and likely symptoms of contamination in the hydraulic system
- methods of checking that components are fit for purpose and the uses of inspection/measuring equipment (such as gauges, micrometers, Verniers, dial test indicators, mirrors, endoprobes, boroscopes, video probes, scales)
- how to identify defects and wear characteristics, and the need to replace 'lifed' items (such as filters, seals and gaskets)
- how to check that replacement components have the correct part/identification markings
- why electrical bonding is critical and why it must be both mechanically and electrically secure
- how to reassemble the components (such as the use of gaskets and seals, jointing/sealing compounds; ensuring correct tightness of fittings and connections; eliminating stress on pipework/connections; carrying out visual checks of all components; checking security of joints and that the system is safe to re-pressurise)
- why securing devices need to be tightened to the correct torque, locked and labelled and the different methods that are used
- the tools and equipment used in the overhauling activities and their calibration/care and control procedures
- how to make adjustments to components/assemblies to ensure that they function correctly (such as setting working clearance, setting travel)
- the recording documentation to be completed for the activities undertaken and, where appropriate, the importance of marking and identifying specific pieces of work in relation to the documentation
- the need to control and account for all tools and equipment used during the overhauling activity
the procedure for the safe disposal of waste materials, scrap components and used hydraulic fluids
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 overhauling activities:
- obtain and use the appropriate documentation (such as job instructions, aircraft manuals and overhauling documentation, 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 the hydraulic equipment is suitably supported and that appropriate lifting and handling equipment is available
- ensure the safe depressurisation of the hydraulic equipment (where appropriate)
- carry out the overhauling activities, using approved techniques and procedures at all times
- ensure that components and equipment are maintained free from damage and foreign objects
- return all tools and equipment to the correct location on completion of the activities
Carry out the overhauling activities to unit level on three of the following types of aircraft hydraulic equipment:
- main undercarriage
- flying controls
- doors (such as cabin, cargo, hold)
- nose undercarriage
- rotor brakes
- weapon bay doors
- tail undercarriage
- blade fold
- emergency systems
- nose wheel steering
- main rotor control
- utility systems
- main gear steering
- tail rotor control
- ram air turbine (RAT)
- wheel braking system
- spoilers
- damping mechanisms
- outriggers
- other specific hydraulic systems (such as hoists)
Carry out all of the following activities, as applicable to the equipment being overhauled:
- cleaning parts prior to dismantling
- checking components for serviceability (such as visual, measurement, NDT, use of probes/scopes)
- pre-disassembly checks and tests
- releasing stored pressure (where applicable)
- dismantling units to component level
- dismantling equipment to unit/sub-assembly level
- replacing all damaged or defective components
- draining/removing any remaining fluids
- fitting blanks to openings to prevent entry of contaminating debris
- reassembling equipment
- making mechanical connections
- setting and adjusting replaced components
- proof-marking/labelling of components
- tightening fastenings to the required torque
- replacing all 'lifed' items (such as piston seals, dust caps, filters, gaskets)
- securing components using mechanical fasteners and threaded devices
- applying locking and retaining devices (such as circlips, pins, wire locking, lock nuts, stiff nuts, swage nuts)
Carry out overhauling activities to component level on two of the following hydraulic components:
- pumps
- pressure intensifiers
- brake units
- hydraulic motors
- accumulators
- actuators/rams
- oil coolers
- cylinders
- control valves
- reservoirs/tanks
- undercarriage legs
- powered flying control units
- other specific components
Replace a range of hydraulic components, to include eight of the following:
- pipework and hoses
- actuating mechanisms
- spring mechanisms
- pistons
- plungers
- gauges
- spools
- bearings
- gaskets
- valves and seats
- rollers
- sensors
- diaphragms
- regulators
- static and dynamic seals
- filters
- housings
- hydraulic fuses
- other specific components
Carry out checks and tests on the overhauled equipment, to include three of the following:
- visual inspection for completeness and freedom
- range of movement/extension from damage or foreign objects
- standard serviceability test
- leak test
- 'special-to-type' tests
- pressure test
Overhaul aircraft hydraulic equipment in compliance with one of the following:
- Civil Aviation Authority (CAA)/European Aviation Safety Agency (EASA)
- Ministry of Defence (MoD)
- Military Aviation Authority (MAA)
- Aerospace Quality Management Standards (AS)
- Federal Aviation Authority (FAA)
- BS, ISO or BSEN standards and procedures
- customer standards and requirements
- company standards and procedures
- aircraft manufacturer's requirements
Complete the relevant paperwork, to include one from the following and pass it to the appropriate people:
- job cards
- computer records
- aircraft service/flight log
- aircraft log book
- 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