CASA Regulation CAR 42ZE states that maintenance on aircraft, including NDT, must be certified by a person either using an approved system of certification, and many maintenance organisations have certification systems approved by CASA; or certify in accordance with the CASA system of certification. The person performing the NDT carries the responsibility for the inspection, and may certify for the conduct of the work and the veracity of the test results. However, the licensed aircraft maintenance engineer makes a final airworthiness certification of the maintenance, which will include due consideration of the results of any NDT. An NDT technician approved by a person holding a CASA 42ZC (7) Instrument of Delegation, may certify for an NDT inspection, provided the inspection is within the scope of the approved person, and is done on behalf of the CAR 30 organisation which holds the Instrument. This situation is where an employer is authorised by CASA to approve its own NDT staff. A person holding a valid Airworthiness Authority for NDT issued under part 33B of the Regulations may certify for an NDT inspection, provided the inspection is within the scope of the Authority, and he/she is working under an agreement with a CAR30 maintenance organisation. A CASR Part 145 Approved Maintenance Organistation may authorise those employees to perform and certify for NDT who satisfy the authorisation requirements shown in the organisation's Exposition.

Approved NDT data can come from several sources; the Type Certificate holder (or Supplementary Type Certificate holder), also known as the Original Equipment Manufacturer (OEM), is the prime source of approved NDT data. Additionally, CASA may provide NDT instructions approved under their authority as the Airworthiness Regulator. For NDT inspection instructions which are developed by maintenance organisations or operators, these may be approved by the organisation if they have appropriately authorised engineers, such as CAR 2A or CAR 35. Alternatively NDT inspection instructions may be drafted by a NDT Technician and forwarded to CASA for CAR 2A (4) approval with or without a Level 3 or CAR 35 Engineers input. However, a CAR 2A (4) delegate within CASA is a tertiary qualified engineer. A CASR Part 145 AMO may under certain conditions develop NDT data which must be approved for use by the CASR Part 42 CAMO responsible for the airworthiness management of the aircraft. For more clarity and order of precedence for NDT approved data refer to the CASA AWB 02-060 Issue 1 – 18 September 2017

The responsibility for the provision of NDT data to the NDT technician and the accuracy of that data rests with the maintenance organisation in CAR 30 and the Part 42 CAMO in Part 145. If there are any inconsistencies, errors or ambiguities in NDT data it should be referred to the engineering representative of the maintenance organisation. Reference to AWB 02-060 Issue 1 – 18 September 2017 and CAR 50E may resolve the inconsistency. If not, you may have to consult a CAR 35 delegate or Level 3 for clarification.

CASA is preparing more up to date documents to replace these CAOs. The two CAOs are only used if the OEM data doesn't specify a standard, and even then their use must be approved by either a CAR 35 delegate or a NDT Level 3.

If your organisation conducts NDT on aircraft, engines or components, the NDT staff, whether they be employed or contract staff, must meet minimum requirements set by CASA The requirements for CASA NDT Authorities reflect Level 2 of AS-3669, as do the renewal requirements.CAO 100.27 states the requirements for new or renewal NDT Maintenance Authorities. If your organisation is a Part 145 AMO and conducting NDT its Exposition document will state the standard for NDT qualifications. This will be the standard to be followed.

At this time CASA does not mandate that organisations engage a Level 3. However, there are some processes which will from time to time require input by a NDT Level 3, which may be contracted.

AS 3669 is an employer based approval standard. Only the employer approves NDT staff. The Level 3 has a role in assessing and prescribing NDT training, and assessment of NDT personnel. The Level 3 may recommend but does not approve NDT staff.

The written practice is an exposition which outlines how an organisation implements AS 3669 or alternate standard permitted by CASA.

The exposition for NDT or "written practice" need not be a lengthy document. It should contain sufficient detail for non NDT/Quality personnel to follow. It is not to be a blatant rewrite of the standard.

For any of the standards which apply to NDT, go to the Standards Australia web site www.standards.org.au . If it is not an Australian standard you are seeking, then use the links from that site to the relevant standards organisation which publishes the standard you require.

EN4179 and NAS 410 carry statements that they are technically equivalent to one another, they do not state that they are technically equivalent to AS3669, although AS3669 has a statement that it is technically equivalent to NAS 410 and EN4179. This simply means that neither the EN nor NAS have considered the Australian Standard for equivalence. The 2014 versions of NAS 410 and EN 4179 carry different requirements around the formal training hours required, vision requirements and the re-approval of personnel. They also now recognise Thermography and Sherography as common methods. If your organisation needs to apply either the EN or NAS it should examine the standards carefully and seek interlpretation assistance from a suitable Level 3. In the application of these standards, it will be the various Airworthiness Regulators, or National Airworthiness NDT Boards which will accept or reject the standards as equivalent. Each of these standards describes an employer based approval system for their NDT staff. Accordingly, any person approved under one standard and moving to an employer who uses another, will need to be assessed by that employer against the employer's NDT approval procedures contained in its written practice. Being approved under one standard does not guarantee approval under the other, but it is a valid starting point for an employer to make a judgement of a person's suitability and competence.