CASR 21M – What exactly is it?

POSTED ON February 28, 2020

The CAR and CASR vest specific regulatory powers which include approvals of designs for aircraft and aeronautical products. The regulations also recognise that in certain circumstances, it may be appropriate for suitable industry personnel to exercise some of these powers, achieved through the issue of Instrument of Appointments (IoAs). These IoAs are issued under CAR 6 and CASR 201.001.

An applicant for an IoA to carry design approval functions may apply for appointment in one or more of the following engineering specialities:

  • Structures
  • System & Equipment (Mechanical)
  • System & Equipment (Electrical)
  • System & Equipment (Avionics)
  • Flight Analyst
  • Powerplant Installation
  • Engines
  • Propellers

CASR Part 21 subpart M replaces the old CAR (1988) Regulations 35 and 36 by codifying in the statutes a number of concepts that were previously expectations of standard practices under the old regulations. These include a number of formal definitions:

  • Design Approval Holder being the person/organisation that is responsible for managing the design data following approval through the life of the product.
  • Technical Data is explicitly defined comprising all the data that is required for defining the design as approved
  • Applicant is explicitly defined as the entity producing the Technical Data for approval. Although this need not be the same as the approver of the data it is the norm for the approving organisation to also produce the design.

The process for approval of a design is now much more rigorously defined in the statutes and closely aligned to the EASA Part 21 Subpart M (and J) requirements.

The following figure illustrates at a very high level the inputs, process and outputs of approval in accordance with CASR 21M:

The key features of the CASR21M approval process are:

  1. There must be a formal application for approval of a design to the approving organisation by the Applicant
  2. The Technical Data is required to define the design and show the design complies with the applicable airworthiness standards.
  3. The Compliance Statement is the controlling document for the approval and identifies:
    1. applicable airworthiness regulations
    2. relevant design requirements
    3. means of showing compliance
  4. Certification of compliance is made using CASA Form 979 or alternative acceptable to CASA

Once approved, the Technical Data is held by the Design Approval Holder for the life of the modification/repair. The DAH has responsibilities to ensure that support is available to the Registered Operators in relation to continued airworthiness of the modification/repair. As it is possible the mod/repair may remain in service longer than the DAH may remain in business, the DAH may enter into a contract with another suitable organisation to transfer that responsibility as defined in CASR 21.450.

The reason for this is that there is only one DAH for a particular design approved under CASR21M and the ‘Owner’ of that design needs to be immediately identifiable to both Registered Operators and CASA. Should there be no organisation acting in the role of DAH then the approval of the design may be suspended.

As is the norm in Europe with approvals made by EASA 21J organisations, the Applicant and Design Approval Holder are generally the same entity for the purposes of applying CASR21M unless there is a contract with a Client specifying otherwise.