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Elements and Performance Criteria

1. Inspect light aircraft AC instrument systems, power supplies and components
   • Relevant maintenance documentation and modification status, including system defect reports, where relevant, are used to identify specific inspection requirements
   • Isolation tags are checked and aircraft configured for safe system inspection and operation in accordance with the applicable maintenance manual
   • AC instrument system and AC power supply components are visually or physically checked for external signs of defects in accordance with applicable maintenance manual while observing all relevant work health and safety (WHS) requirements
   • Defects are correctly identified and reported
2. Test/adjust light aircraft AC instrument systems, power supplies and components
   • Aircraft and system are prepared in accordance with applicable maintenance manual for the application of power/system operation
   • Instrument system and AC power supply is functionally tested in accordance with maintenance manual for evidence of serviceability or malfunction
   • System calibration or adjustments are performed in accordance with maintenance manual, as appropriate
3. Troubleshoot light aircraft AC instrument systems, power supplies and components
   • Available information from maintenance documentation, inspection and test results is used, where necessary, to assist in fault determination
   • Maintenance manual fault diagnosis guides and logic processes are used to ensure efficient and accurate troubleshooting, using test sets, downloaded maintenance data and fault-finding charts or similar, to line replacement level
   • Specialist advice is obtained, where required, to assist with the troubleshooting process
   • Instrument system or power supply faults are located and the causes of the faults are clearly identified and correctly recorded in maintenance documentation, where required, in accordance with standard enterprise procedures
   • Rectification requirements are determined
4. Remove and install light aircraft AC instrument system, and power supply components
   • System is rendered safe and prepared in accordance with the applicable maintenance manual and isolation tags are fitted, where necessary, to ensure personnel safety
   • Instrument or power supply component removal is carried out in accordance with the applicable maintenance manual while observing all relevant WHS requirements
   • Required maintenance documentation is completed and processed in accordance with standard enterprise procedures
   • Removed components are tagged and packaged in accordance with specified procedures
   • Instrument or power supply components to be installed are checked to confirm correct part numbers, modification status, serviceability and shelf life
   • Physical installation of instrument or power supply components is performed in accordance with the applicable maintenance manual and regulatory requirements, ensuring appropriate adjustment/alignment is carried out
   • System is reinstated to correct operational condition in preparation for testing, as necessary

Range Statement

This field allows for different work environments and conditions that may affect performance. Essential operating conditions that may be present (depending on the work situation, needs of the candidate, accessibility of the item, and local industry and regional contexts) are included.
AC instrument systems and AC power supply components include:	Directional gyro (DG), artificial horizon (AH), attitude heading and reference system (AHRS) and components, servo and encoding altimeters, and remote reading gyro compasses and components Piston engine and gas turbine engine indication system components Fuel quantity indication and flow indication systems and components Transmitter/indicator measuring instrument systems (pressure, temperature and vacuum) and components Inverters and transformer/rectifier units
Procedures and requirements include:	Industry standard procedures specified by manufacturers, regulatory authorities or the enterprise

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Performance Evidence

Evidence required to demonstrate competency in this unit must be relevant to and satisfy all of the requirements of the elements and performance criteria under the specified conditions of assessment, and include:

using approved maintenance documentation and aircraft publications relating to AC instrument systems and related AC power supplies

locating and identifying AC powered instrument system components including:

AH, DG, AHRS, servo and encoding altimeters

engine system temperature, speed, oil pressure, torque and manifold pressure

auxiliary systems, including vacuum, fuel storage quantities and fuel flow

remote reading gyro compasses

locating and identifying AC instrument power supply system components, including:

inverters

transformer/rectifier units

voltage and frequency indication

correctly handling and observing maintenance precautions for gyroscopes and gimbals

recognising system and component defects/external damage, correct installation, connection of plugs, terminations, attaching hardware (including cabling/harnesses) and security in AC powered instruments and related power supply, including:

flight instruments

remote reading gyro compasses

piston engine and gas turbine engine indication systems (indicators and transmitters/sensors)

fuel quantity and flow indication systems (indicators, probes and transmitters)

transmitter/indicator measuring instrument systems (pressure, temperature and vacuum)

AC power supply, including inverters and transformer/rectifier units

applying logic processes, taking and interpreting system measurements, using test equipment and appropriate wiring diagrams and manuals to isolate malfunctions in the above systems

performing system functional tests and checks to isolate system faults and assess post-maintenance serviceability

applying WHS requirements relevant to instrument and electrical system maintenance.

It is essential that system testing procedures, cleanliness requirements and safety precautions applicable to the system being maintained are fully observed, understood and complied with. Ability to interpret inspection procedures and specifications (allowable limits) and apply them in practice across a range of inspection, testing and troubleshooting applications (including the timely involvement of supervisors or other trades) is critical.

Evidence of transferability of skills and knowledge related to inspection, testing and troubleshooting is essential. This is to be demonstrated through application across a range of AC powered aircraft instrument systems, AC power supplies and components listed in the Assessment Conditions.

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Knowledge Evidence

Evidence required to demonstrate competency in this unit must be relevant to and satisfy all of the requirements of the elements and performance criteria and include knowledge of:

component attachment methods

connection of hardware and plugs

handling precautions for electrostatic sensitive devices

relevant WHS practices

AC theory:

calculations and measurement in AC circuits

inductors and inductive reactance

transformer operation

capacitors and capacitive reactance

LCR circuits and resonance

passive filters

power relationship in reactive circuits

the basic layout (block diagram level), function and operation of AC powered:

flight instruments

remote reading gyro compasses

piston engine and gas turbine engine indication systems (indicators and transmitters/sensors)

fuel quantity and flow indication systems (indicators, probes and transmitters)

transmitter/indicator measuring instrument systems (pressure, temperature and vacuum)

AC power supply including AC generators, inverters and transformer/rectifier units

the operating principles of the above systems and associated with:

atmospheric conditions – properties and effects on aircraft instruments and systems

pressure and temperature sensing elements and their use in aircraft instrument systems

gyroscopes and their use in aircraft instrument systems

electrical fundamentals

relevant maintenance documentation and maintenance publications

maintenance requirements and troubleshooting procedures.

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