Maintaining navigation systems on aircraft
Overview
This standard identifies the competences you need to carry out maintenance activities on aircraft navigation systems, in accordance with the aircraft maintenance manual, approved change documentation (service bulletin) and airworthiness requirements. It covers both fixed wing and rotary winged aircraft, and includes units and components which provide aircraft navigational information, as applicable to the aircraft type. The maintenance activities will include the removal, fitting and testing of a range of navigational components. You will be required to select the correct tools and equipment to use, based on the operations to be performed and the components to be removed or replaced. The aircraft system components will include items such as air data computers, pitot/static, distance measuring equipment (DME), very high frequency omnidirectional range (VOR), instrument landing (ILS), auto direction finder (ADF), global positioning (GPS), Doppler, long range navigation (LORAN), homing, inertial navigation system (INS), compasses and other devices, as applicable to the aircraft type. You will remove the required components and fit approved replacements, as appropriate. You will then need to test and adjust the completed system to meet the aircraft maintenance manual, change documentation (service bulletin) and airworthiness requirements.
Your responsibilities will require you to comply with the specific practices and procedures identified in the aircraft manual, change/service bulletin documentation and airworthiness requirements for the maintenance activities undertaken, and to report any problems with these activities that you cannot personally resolve, or that are outside your permitted authority, to the relevant people. You must ensure that all tools, equipment and materials used are correctly accounted for on completion of the activities, and that all necessary job/task documentation is completed thoroughly, 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 the appropriate maintenance techniques and procedures to aircraft navigational systems. You will understand the removal, fitting and testing methods and procedures, and their application, along with the navigational system maintenance requirements. You will know how the equipment functions, the common problems that can occur, the purpose of the individual components and associated defects, in adequate depth to provide a sound basis for carrying out the maintenance activities, correcting faults and for ensuring that the equipment is maintained to the required standard. You will understand the safety precautions required when working on the aircraft navigational systems, and when using the associated tools and equipment. 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.
Notes:
- This standard is designed to cover the practical experience requirements of the Airline Transport Association (ATA) Chapter 34 Navigation.
- To display competence in this standard, it is necessary to both remove and fit aircraft navigation system components. You must remove components; however, you may fit a replacement component where the original was previously removed by another person. You should also be aware of how to leave a system in a safe condition if maintenance tasks cannot be completed. This covers both the physical systems and the job documentation.
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 maintenance schedules to carry out the required work
- carry out the maintenance activities within the limits of your personal authority
- carry out the maintenance activities, and replace components in the specified sequence and in an agreed timescale
- report any instances where the maintenance activities cannot be fully met or where there are identified defects outside the planned schedule
- complete relevant documentation in accordance with organisational requirements
- dispose of waste materials in accordance with safe working practices and approved procedures
- leave the aircraft and system in a safe and appropriate condition, free from foreign object debris on completion of the activities
Knowledge and Understanding
You need to know and understand:
- the specific safety practices and procedures that you need to observe when working with aircraft navigation systems (including any specific legislation, regulations/codes of practice for the activities, equipment or materials)
- the importance of maintenance on aircraft navigation systems and equipment, and the impact upon Extended Range Twin-Engine Operations Procedures (ETOPS) systems, RVSM requirements, Autoland systems/status requirements, Elementary and Enhanced Mode 'S' Surveillance, Electrical Wiring Interconnect Systems (EWIS), legislation and local/company/customer procedures
- the hazards associated with removing, fitting and testing aircraft navigation system components, and with the tools and equipment used, and how to minimise them and reduce any risk
- 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 protective equipment that you need to use for both personal protection (PPE) and protection of the aircraft
what constitutes a hazardous voltage and how to recognise victims of electric shock
how to reduce the risks of a phase to earth shock (such as insulated tools, rubber matting and isolating transformers)
the importance of aircraft husbandry and of ensuring that, throughout the maintenance activity, the aircraft and work area are maintained free from foreign objects, and the implications of FOD to the safety of the aircraft
- how to extract and use information from aircraft manuals, log books, flight logs, charts, circuit and physical layouts, specifications and other documents needed in the maintenance process
- how to carry out currency/issue checks on the specifications you are working with
- terminology used in aircraft navigation systems, and the use of system diagrams and associated symbols
- the principles of operation of the aircraft navigation system being worked on, and the function of the various units within the system
- the various mechanical fasteners that are used, and their methods of removal and replacement (such as threaded fasteners, special securing devices)
- the importance of using the specified fasteners for the installation, and why you must not substitute others
- why securing devices need to be locked and labelled, and the different methods that are used to remove and install them
- the torque loading requirements on the fasteners and what to do if these loadings are exceeded or not achieved
- the various types of electrical connector that are used, methods of unlocking, orientation indicators and locating and locking-in of the connections
- the techniques used to remove components from aircraft navigation systems without damage to the components or surrounding structure (such as proof marking, the need to protect the circuit integrity by covering and labelling exposed circuits)
- the importance of applying electrostatic discharge (ESD) avoidance procedures when working on sensitive equipment or devices
- the need to label and store correctly components that require repair or overhaul, and to check that replaced components have the correct part/identification markings and accompanying release documentation
- the techniques used to position, align, adjust and secure the replaced components to the aircraft without damage to the components or surrounding structure
- methods of lifting, handling and supporting the components/equipment during the maintenance activities
- why electrical bonding is critical, and why it must be both mechanically and electrically secure
- the tools and equipment used in the maintenance activities and their calibration/care and control procedures
- why tool/equipment control is critical and what to do if a tool or piece of equipment is unaccounted for on completion of the activities
- how to recognise defects (such as incorrectly seated plugs and sockets, ineffective fasteners, foreign object damage or contamination)
- how to carry out routine checks and servicing of the aircraft navigation system
- the need to check that cabin/cockpit switches, selectors and circuit breakers are in the correct position before applying any form of external power (such as electrical, hydraulic, air or vacuum)
- the types of test to be carried out on the aircraft navigation system and the test equipment to be used
- the methods and procedures to be used to carry out the various tests on the navigation system
- the importance of carrying out the tests in the specified sequence, checking readings/movements at each stage
- how to record the results of each individual test and the documentation that must be used
- how to analyse the test results and make valid decisions about the acceptability of the aircraft navigation systems
- the procedures to be followed if the equipment or system fails to meet the test specification
- the problems that can occur with the aircraft navigation system maintenance operations and how these can be overcome
- 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 procedure for the safe disposal of waste materials and scrap components
- the extent of your own authority and to whom you should report if you have problems that you cannot resolve
Scope/range
Scope Performance
Carry out all of the following during the maintenance of the aircraft navigation system:
- ensure that appropriate authorisation to work on the aircraft is obtained, and observe all relevant isolation and safety procedures
- obtain and use the correct documentation (such as job instructions, technical instructions, aircraft manuals and maintenance documentation)
- obtain the correct tools and equipment for the activity, and check that they are in a safe, tested and usable condition and within current calibration dates
- 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
- ensure that the relevant safety devices and mechanical/physical locks are in place (where appropriate)
- where appropriate, apply electrostatic discharge (ESD) avoidance procedures
- use approved removal, fitting and testing techniques and procedures at all times
- return tools and equipment to the correct storage location on completion of the activities
- ensure that work carried out is correctly documented and recorded
- ensure that any outstanding tests are correctly documented
Carry out maintenance on three of the following parts of aircraft navigation systems:
- flight environment data (such as central air data computers, pitot/static, rate-of-climb, air speed, high speed warning, altitude, altitude reporting, altimeter correction, air disturbance detection, air temperature)
- attitude and direction (such as magnetic compasses, vertical and directional references, magnetic heading systems, attitude director systems, symbol generators, turn and bank, rate of turn)
- landing and taxiing aids (such as localizer, glide slope, instrument landing systems (ILS), markers and paravisual director ground guidance systems, microwave landing systems (MLS), radio altimeter
- independent position determining (such as inertial guidance systems, weather radar, Doppler, enhanced ground proximity warning system (EGPWS), traffic collision avoidance system (TCAS))
- dependant position determining (such as distant measuring equipment (DME), long range navigation (LORAN), very high frequency omnidirectional range (VOR), auto direction finder (ADF), global positioning system (GPS)
- flight management computing (such as course computers, flight management, performance data computers)
Remove and fit six different aircraft navigation system components (at least four must be from group A):
Group A
1. airspeed indicator
2. air data computer
3. analogue/digital converters (A-D/D-A)
4. altimeter
5. VHF nav receiver
6. navigation display units (including head-up)
7. vertical speed indicator
8. ADF receiver
9. horizontal situation indicator unit (HSI)
10. satellite beacons
11. transmitter units
12. computers (such as FMS, EGPWS,TCAS)
13. ATC and DME transponders
14. control units
15. heading and vertical reference gyro
16. compensation units
17. interface units
18. attitude/direction indicator (ADI)
19. compass flux valve
20. DME indicator
21. radio magnetic indicator
22. standby compass
23. receiver units
24. standby/artificial horizon
25. radio altimeter
26. aerials
27. weather radar Tx/Rx
28. pitot/static probes/plates/sensors
29. weather radar antenna
Group B
30. batteries
31. unit trays
32. plugs/sockets
33. switches
34. instruments/gauges/indicators
35. transformers
36. relays
37. wires/cables/antenna
38. line replacement units (LRU)
39. circuit breakers
40. feeder/waveguide
41. other specific components
Carry out fifteen of the following maintenance activities:
- removing access panels and covers to expose components to be removed
- carrying out fault diagnosis and system checks
- preparing the system for maintenance (such as isolating)
- disconnecting electrical connections
- refitting components in the correct position, orientation and alignment
- removal of bonding
- removing cable securing devices
- setting and adjusting/tuning replaced components (such as power output, voltage)
- removing securing devices and mechanical fasteners
- supporting equipment to be removed
- making mechanical connections
- dismantling equipment to an appropriate level
- making electrical connections
- covering (protecting) exposed components, wires,
- carrying out bonding pipework or vents
- installing cable securing devices
- checking components for serviceability
- torque loading as required
- replacing damaged/defective components
- checking the function of equipment
- ensuring that replacement components have the correct part numbers
- labelling (and storing in the correct location) components that require repair or overhaul
- applying bolt locking methods (such as split pins, wire locking, lock nuts)
Service/check aircraft navigation systems, to include carrying out six of the following:
- checking calibration of magnetic direction indicator
- functional check weather radar
- checking pitot static system for leaks
- functional check Doppler
- checking of pitot static instruments
- functional check TCAS
- checking operation of directional directional/vertical reference gyros and indication systems
- functional check DME
- functional check of VOR
- checking calibration of pressure altitude reporting system
- functional check ATC transponder
- checking instrument landing systems
- functional check stand-alone flight director system
- checking marker systems
- checking the satcom system
- functional check inertial navigation/reference system
- checking GPS
- checking of radar altimeter
- carrying out FMS/ EGPWS database update
- functional check FMS
- functional check ADF
Carry out four of the following types of test/check on aircraft navigation systems:
- functional check
- built in test equipment BITE test
- signal-to-noise checks
- bonding tests
- power output
- continuity checks
- standard serviceability checks
- compass swing
- 'special-to-type' tests
- applying a dummy load
- distant object test
- time-domain reflectometer (TDR) checks
- voltage standing wave ratio (VSWR) checks
- signal injection tests
- receiver sensitivity
- distortion checks
Using four of the following:
17. multimeter
18. headset
19. bonding tester
20. oscilloscope
21. 'special to type' test equipment
22. reference gyros
23. radio frequency (RF) signal generators
24. delay lines
25. external power source (electrical/hydraulic)
26. time-domain reflectometer (TDR) equipment
27. aircraft power source (electrical/hydraulic)
28. voltage standing wave ratio (VSWR) equipment
29. vacuum systems
Complete the relevant paperwork, to include one from the following and pass it to the appropriate people:
- job cards/work sheets
- aircraft cabin log
- computer records
- aircraft log book
- aircraft technical log
Carry out maintenance on aircraft navigation systems in compliance with one of the following:
- Civil Aviation Authority (CAA)/European Aviation Safety Agency (EASA)
- Extended Range Twin-Engine Operations Procedures (ETOPS) (where appropriate)
- Ministry of Defence (MoD)
- Military Aviation Authority (MAA)
- Aerospace Quality Management Standards (AS)
- Federal Aviation Authority (FAA)
- aircraft maintenance manual/approved change documentation (service bulletin)
- manufacturers standards and procedures
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