Airworthiness Regulation

by Lindsay Wise & Phil Vabre

At the conclusion of the Great War in 1919, with the influx of aircraft to be used for civil purposes, the Australian Government introduced a Bill giving effect to the International Convention for the Regulation of Air Navigation (known as ICAN) which was signed in Paris on October 13, 1919. As a result the Air Navigation Act 1920 was passed on December 2, 1920. Regulations were drawn up under the Act to provide for, amongst other things, the periodical inspection of aircraft and the licensing of personnel engaged in the maintenance of aircraft. The Act and associated Regulations came into force on March 28, 1921.


Ground Engineer's Licences were issued under the Air Navigation Regulations in the following categories:

  • Division 'A' - Inspection of aircraft undergoing construction or complete overhaul
  • Division 'B' - Inspection of aero engines undergoing construction or complete overhaul
  • Division 'C' - Inspection of aircraft before flight
  • Division 'D' - Installation and inspection of aero engines before flight
  • Division 'X' - Inspection and certification of other work

To be eligible to sit for examination applicants had to be 21 years of age and have had satisfactory practical experience in the maintenance or overhaul of engines and/or aircraft for which the licence was required. The 'overhaul' licences were cancelled in the mid 1950s and maintenance licences only were issued for aircraft, engines, electrical systems, instrument systems and radio systems. Ratings for each aircraft type for which the individual is qualified to maintain were, and are, endorsed on the licence.

Aircraft Inspectors were appointed to the Civil Aviation Branch and were the fore-runners of the Aircraft Surveyors and Airworthiness Surveyors of later years. Today these people are known as Airworthiness Inspectors and Airworthiness Officers, depending on their role. They are drawn from the aircraft industry and are required to hold licences in a least two categories or similar military standards and demonstrate extensive experience in maintenance of aircraft. Airworthiness Inspectors are responsible for:

  • licensing of Aircraft Maintenance Engineers and the issue of authorisations for various activities not covered by a licence, e.g. welding, weighing of aircraft, non-destructive testing (NDT) procedures
  • monitoring and surveillance of organisations holding Certificates of Approval for various activities associated with the maintenance of aircraft, together with spot checks on aircraft to ensure that a satisfactory standard is being maintained
  • approval of systems of maintenance for aircraft and investigation of aircraft defects

Surveyors also used to be provided with training on new aircraft or equipment introduced by an operator to ensure that their knowledge was continually updated.

Later, Aeronautical Engineers were added to the airworthiness staff. Their responsibility was, and is, approving the manufacture of, and modifications to, aircraft and assessing aircraft performance requirements.

CAB Bristol Tourer G-AUCA - click here for larger From the 28th of June 1921 every aircraft was required to be entered in the Aircraft Register maintained by the Civil Aviation Branch and its sucessors (today the Civil Aviation Safety Authority). Once entered on the Register, an aircraft is issued with an identifying Registration Mark. Originally these were composed of the prefix letter G followed by four individual letters, the first two of which were AU (e.g. G-AUCA). From 1928, all Australian aircraft were required to change their markings to the prefix VH followed by three individual letters (e.g. VH-UAB).

Once added to the Register, a Certificate of Registration (C of R) is also issued. In the past the C of R was issued to a person who may not be the owner but was the person responsible for the continuing airworthiness of the aircraft. From November 2004, new Civil Aviation Safety Regulations in Part 47 require the C of R to be issued to an owner, while a new position of Registered Operator is responsible for the airworthiness of the aircraft.

Following the initial certification of an aircraft type in Australia or overseas, it is issued with a Type Certificate (TC) indicating it conforms to an appropriate design standard. This is usually an international standard, e.g. United States FAA or United Kingdom Civil Aviation Authority.

The process required to operate an aircraft in Australia also includes steps to ensure that the aircraft has been designed and manufactured to appropriate standards Once this is established, by ensuring the aircraft complies with its TC, the aircraft is issued a Certificate of Airworthiness (C of A). Special Certificates of Airworthiness or Experimental Certificates of Airworthiness (and formerly Permits to Fly) may be issued to some aircraft that would not otherwise qualify for a normal C of A. These Certificates or Permits may specify conditions under which the aircraft may be operated. In this context it is also worth noting that there are many aircraft, such as ultralights, that are not registered on the Australian (VH) Register and thus are not covered by the need for a C o f A. They are instead controlled by other bodies such as self-administering sport aviation organisations.

To ensure that it retains an acceptable standard of airworthiness throughout its life, an aircraft is required to be maintained in accordance with an approved Maintenance Schedule or System of Maintenance. The Schedule may be that provided by the manufacturer, one designed by the operator and approved by the civil aviation regulatory authority, or one specified by the authority in regulatory publications. Included in the system are periods at which maintenance, e.g. inspections, tests, component changes, is to be carried out.

To perform major disassembly, periodic or annual inspection on an aircraft a person must hold a Certificate of Approval issued by the Civil Aviation Safety Authority to cover the maintenance in question. All maintenance on aircraft must be performed and certified by appropriately authorised persons. This is usually done by either a Licenced Aircraft Maintenance Engineer (LAME). Pilots are permitted to perform and certify limited maintenance on aircraft for which they are licenced to fly and have the applicable data, tools and training. It is also worth noting that today there are categories of aircraft, for example ultralights and some amateur-built aircraft, which are not required to be maintained by a LAME.

All defects which may significantly affect the airworthiness of an aircraft must be reported to the regulatory authority as soon as possible. In recent times this reporting requirement has also been extended to the TC holder. In the past defects would be investigated by an Airworthiness Surveyor and in consequence might be considered as a basis for promulgation of a mandatory replacement, modification and/or inspection requirement by means of an 'Airworthiness Directive'. These days the TC holder may also promulgate corrective work by means of a Service Bulletin, compliance with which is mandatory. Aircraft and component manufacturers also issue service information such as 'Service Instructions' which contain recommendations as to when certain work should be carried out. In the case of significant items these may be also adopted as an Airworthiness Directive by the regulatory authority.

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