Managing defects in a Part 43 aircraft or aeronautical product

Learn more about dealing with defects in aircraft, or in aeronautical products for aircraft, under the proposed general aviation maintenance regulations (Part 43 of the Civil Aviation Safety Regulations 1998 (CASR)) and the Part 43 Manual of Standards.

Who should read this?

  • Registered operators of aircraft that will operate under Part 43 of CASR
  • CAR30 organisations
  • Part 145 Approved Maintenance Organisations
  • Licensed aircraft maintenance engineers
  • Aircraft maintenance technician certificate holders
  • holders of inspection authorisations

What will be classified as a defect under Part 43 of CASR

A defect is generally taken to be any fault or imperfection in an aircraft or aeronautical product for an aircraft that is not within design tolerances. It may be the result of manufacturing fault, wear, misuse, maintenance errors or accidental damage.

A major defect is a defect of such a kind that it may affect the safety of the aircraft or cause the aircraft to become a danger to persons or property.

The role of the registered operator when a defect is identified

A registered operator of an aircraft (RO) is responsible for having defects rectified.

Under the Part 43 Manual of Standards (MOS), if an instrument or item of equipment is not required by the certification basis for the aircraft to be operable and is not required by the regulations or the Part 43 MOS for a flight or type of operation, then the RO may defer rectification until the next scheduled inspection. However, the RO must placard as “INOPERATIVE” the instrument or item of equipment that is inoperable, and its cockpit control. This is to ensure the pilot is then aware of any unserviceabilities.

The RO must also ensure that the maintenance records for the aircraft include information about any rectification of a defect or damage that is not deferred.

The RO must report, in writing, major defects to CASA and the type certificate holder or, if applicable, the supplemental type certificate holder, within 2 days of becoming aware of the major defect.

The role of the maintainer when a defect is identified

If during maintenance, a maintainer finds a major defect, the maintainer must advise the RO.

If a defect is found during a scheduled inspection, the inspection authorisation holder must provide the RO with a signed and dated list of the defects to be rectified before the aircraft may be flown, and with a list of deferrable defects (if any). The maintainer must state in the maintenance records that the RO has been handed a signed and dated list of defects to be rectified before the aircraft is flown and/or deferrable defects.


The content provided in the information sheet is a guide only as to how the rules may work in practice once Part 43 of CASR and the Part 43 Manual of Standards is made and commence.

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