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Maintaining auto flight systems on aircraft

URN: SEMAE3306
Business Sectors (Suites): Aeronautical Engineering Suite 3
Developed by: Enginuity
Approved on: 2021

Overview

This standard identifies the competences you need to carry out maintenance activities on aircraft auto flight systems, in accordance with the approved 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 a means of automatically controlling the flight of the aircraft, including direction, heading, altitude and speed, as applicable to the aircraft type. The maintenance activities will include the removal, fitting and testing of a range of auto flight 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 components will include items such as computers, controllers, air data units, detectors, gyros (rate and vertical), trim units, actuators, stick position cancellers, and angle of attack and stall warning components. 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 requirements 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 auto flight systems. You will understand the removal, fitting and testing methods and procedures, and their application, along with the auto flight 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 auto flight system, 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:

  1. This standard is designed to cover the practical experience requirements of the Airline Transport Association (ATA) Chapter 22 Auto Flight.
  2. To display competence in this standard it is necessary to both remove and fit aircraft auto flight 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:

  1. work safely at all times, complying with health and safety and other relevant regulations, directives and guidelines
  2. follow the relevant maintenance schedules to carry out the required work
  3. carry out the maintenance activities within the limits of your personal authority

  4. carry out the maintenance activities, and replace components in the specified sequence and in an agreed timescale

  5. report any instances where the maintenance activities cannot be fully met or where there are identified defects outside the planned schedule

  6. complete relevant documentation in accordance with organisational requirements
  7. dispose of waste materials in accordance with safe working practices and approved procedures
  8. 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:

  1. the specific safety practices and procedures that you need to observe when working with aircraft auto flight systems (including any specific legislation, regulations/codes of practice for the activities, equipment or materials)
  2. the importance of maintenance on auto flight systems, and impact upon Extended Range Twin-Engine Operations Procedures (ETOPS) systems, RVSM operations, Electrical Wiring Interconnect Systems (EWIS), Autoland system status and legislation and local procedures
  3. the hazards associated with removing, fitting and testing aircraft flight control system components, and with the tools and equipment used, and how to minimise them and reduce any risk
  4. 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

  5. the protective equipment that you need to use for both personal protection (PPE) and protection of the aircraft

  6. what constitutes a hazardous voltage and how to recognise victims of electric shock

  7. how to reduce the risks of a phase to earth shock (such as insulated tools, rubber matting and isolating transformers)

  8. 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

  9. how to extract and use information from aircraft manuals, log books, flight logs, charts, circuit and physical layouts, specifications, symbols used in aircraft flight control systems, other documents needed in the maintenance process
  10. how to carry out currency/issue checks on the specifications you are working with
  11. terminology used in aircraft flight control systems, and the use of system diagrams and associated symbols
  12. the principles of operation of the auto flight system being worked on, and the function of the various units within the system
  13. the various mechanical fasteners that are used, and their methods of removal and replacement (such as threaded fasteners, special securing devices)
  14. the importance of using the specified fasteners for the installation and why you must not substitute others
  15. why securing devices need to be locked and labelled, and the different methods that are used to remove and install them
  16. the torque loading requirements on the fasteners and what to do if these loadings are exceeded or not achieved
  17. the various types of electrical connector that are used, methods of unlocking, orientation indicators and locating and locking-in of the connections
  18. the techniques used to remove components from aircraft auto flight 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)
  19. the importance of applying electrostatic discharge (ESD) avoidance procedures when working on sensitive equipment or devices
  20. 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
  21. the techniques used to position, align, adjust and secure the replaced components to the aircraft without damage to the components or surrounding structure
  22. methods of lifting, handling and supporting the components/equipment during the removal and fitting activities
  23. why electrical bonding is critical, and why it must be both mechanically and electrically secure
  24. the tools and equipment used in the maintenance activities, and their calibration/care and control procedures
  25. 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
  26. how to recognise defects (such as incorrectly seated plugs and sockets, ineffective fasteners, foreign object damage or contamination)
  27. how to carry out routine servicing of the aircraft auto flight system
  28. 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)
  29. the types of test to be carried out on the aircraft auto flight system, and the test equipment to be used
  30. the methods and procedures to be used to carry out the various tests on the auto flight system
  31. the importance of carrying out the tests in the specified sequence, checking readings/movements at each stage
  32. how to record the results of each individual test and the documentation that must be used
  33. how to analyse the test results and make valid decisions about the acceptability of the aircraft auto flight systems
  34. the procedures to be followed if the equipment or system fails to meet the test specification
  35. the problems that can occur with the auto flight system maintenance operations, and how these can be overcome
  36. 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
  37. the procedure for the safe disposal of waste materials and scrap components
  38. the extent of your own authority, and to whom you should report if you have problems that you cannot resolve

Scope/range

Scope Performance

​

  1. Carry out all of the following during the maintenance of the aircraft auto flight system:

    1. ensure that appropriate authorisation to work on the aircraft is obtained, and observe all relevant isolation and safety procedures
    2. obtain and use the correct documentation (such as job instructions, technical instructions, aircraft manuals and maintenance documentation)
    3. 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
    4. 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
    5. ensure that the relevant safety devices and mechanical/physical locks are in place (where appropriate)
    6. where appropriate, apply electrostatic discharge (ESD) avoidance procedures
    7. use approved removal, fitting and testing techniques and procedures at all times
    8. return tools and equipment to the correct storage location on completion of the activities
    9. ensure that work carried out is correctly documented and recorded
    10. ensure that any outstanding tests are correctly documented

  2. Carry out maintenance on two of the following parts of the aircraft auto flight system:

    1. autopilot                           
    2. auto pilot system monitoring
    3. mach trim                     
    4. integrated flight director system
    5. auto throttle                               
    6. aerodynamic load alleviating
    7. auto land systems             
    8. command stability and augmentation system

  3. Remove and fit three different aircraft auto flight system components (at least one must be from group A):

Group A

1.  computers                          
2.  trim units
3.  controllers                        
4.  actuators
5.  amplifier                             
6.  transformers
7.  detectors/position sensors     
8.  stick position cancellers
9.  receiver units                         
10.  embedded GPS and INS (EGI)
11.  gyros (rate and vertical)

Group B
12. batteries                 
13. servos      
14. wires/cables
15. switches                   
16. aerials  
17. plugs/sockets
18. relays                   
19. instruments/gauges/indicators   
20. other specific components

  1. Carry out fifteen of the following maintenance activities:

    1. removing access panels and covers to expose components to be removed
    2. carrying out fault diagnosis and system checks
    3. preparing the system for maintenance (such as isolating)
    4. disconnecting electrical connections   
    5. refitting components in the correct position, orientation and alignment
    6. removal of bonding                                                    
    7. removing cable securing devices                
    8. setting and adjusting/tuning replaced components(such as power output, voltage)
    9. removing securing devices and mechanical fasteners                                                       
    10. making mechanical connections
    11. supporting equipment to be removed        
    12. making electrical connections
    13. dismantling equipment to an appropriate level    
    14. carrying out bonding
    15. covering (protecting) exposed components, wires, pipework or vents      
    16. installing cable securing devices
    17. torque loading as required
    18. checking components for serviceability   
    19. carrying out functional checks of systems
    20. replacing damaged/defective components
    21. ensuring that replacement components have the correct part numbers
    22. labelling (and storing in the correct location) components that require repair or overhaul
    23. applying bolt locking methods (such as split pins, wire locking, lock nuts)
    24. carrying out area inspections prior to task close down

  2. Service/check aircraft auto flight systems, to include carrying out four of the following:

    1. check operation of autopilot            
    2. perform autopilot gain adjustments
    3. check operation of auto throttle         
    4. perform mach trim functional check
    5. check operation of yaw damper         
    6. check autoland system
    7. check and adjust servo clutch             
    8. check stability augmentation system
    9. other specific aircraft auto flight checks

  3. Carry out five of the following types of test/check on aircraft auto flight systems:

    1. functional check 
    2. continuity checks  
    3. audio warning
    4. bonding tests     
    5. signal injection tests          
    6. visual warning
    7. BITE test           
    8. rate/range/sense of movement
    9. 'special-to-type' tests
    10. voltage checks

Using four of the following:
11. simulators                  
12. external power source (electrical/hydraulic)
13. oscilloscope
14. clinometers                    
15. aircraft power source (electrical/hydraulic)
16. reference gyros
17. air data test sets         
18. bonding tester
19. tilt tables                   
20. 'special to type' test equipment
21. multimeter                
22. internal aircraft equipment

  1. Complete the relevant paperwork, to include one from the following and pass it to the appropriate people:

    1. job cards/work sheets
    2. computer records
    3. aircraft technical log
    4. aircraft cabin log
    5. aircraft log book

  2. Carry out maintenance on aircraft auto flight systems in compliance with one of the following:

    1. Civil Aviation Authority (CAA)/European Aviation Safety Agency (EASA)
    2. Extended Range Twin-Engine Operations Procedures (ETOPS) (where appropriate)
    3. Ministry of Defence (MoD)
    4. Military Aviation Authority (MAA)
    5. Aerospace Quality Management Standards (AS)
    6. Federal Aviation Authority (FAA)
    7. aircraft maintenance manual/approved change documentation (service bulletin)
    8. 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

Skills

Glossary

Links To Other NOS

External Links

Version Number

3

Indicative Review Date

2024

Validity

Current

Status

Original

Originating Organisation

Enginuity

Original URN

SEMAE3306

Relevant Occupations

Engineer, Engineering, Engineering and Manufacturing Technologies, Engineering Technicians

SOC Code

5234

Keywords

engineering; aeronautical; removal; fitting; testing; auto flight components; computers; controllers; air data units; detectors; gyros; trim units; actuators; stick position cancellers; angle of attack; stall warning