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Supplemental type certificates
What is a supplemental type certificate?
When a person develops the design of a change to a type-certificated aircraft, aircraft engine or propeller, that design must be approved before it can be used. A supplemental type certificate (STC) is one method of obtaining approval.
If you propose to develop the design of a major change to a type-certificated aircraft, aircraft engine or propeller you should seek an STC, especially if you wish to sell your design to multiple customers.
Further information is available in CASA Advisory Circular – Supplemental Type Certificates AC 21-15 (pdf 436.8 KB).
View the Register of Australian supplemental type certificates on our website.
How to apply for a supplemental type certificate
Submit an application for an STC. Your application should be accompanied by extra information that describes your design and shows how you intend to show compliance with the certification basis. The documents required to obtain an STC are described in AC 21-15.
Step 1 - complete the application form
You will need to complete Application for a type certificate or supplemental type certificate form 733 (pdf 132.17 KB) in five parts (A to E).
The form provides guidelines that will assist you in completing the form correctly. Please read these guidelines carefully. If you have any further questions regarding the form or how to fill it out please do not hesitate to phone Aircraft Certification on 131 757.
Part A - Applicant's details
Part A advises us whether you are an individual or company. You will also need to provide your aviation reference number (ARN). If you do not have an ARN you must provide proof of identification or proof of your company's registration (see application guidelines for acceptable forms of identification).
If you are a foreign applicant you must provide your nationally recognised registration record.
Part B - Designation of aircraft, aircraft engine or propeller
Part B contains changes you may be making to the aircraft, the country in which it was manufactured, who manufactured it and its model designation.
Part C - Description of proposed changes
Part C allows you to describe in detail any changes you are making to the aircraft, aircraft engine or propeller you wish to be approved by issue of an STC. It will help us if you provide the objective of your proposed change.
Part D - Declaration
By signing the declaration, you will be indicating to us that you have:
- read the guidelines
- completed the application in full
- supplied all necessary documents to us to process your application.
It also asks if you are happy to correspond with us via email.
Step 2 - Submit application form
The form should be sent to Aircraft Certification at firstname.lastname@example.org.
Step 3 - Review of your application
Aircraft Certification will review the application to ensure that you have answered the relevant questions and provided the necessary documents.
If the application is incomplete, Aircraft Certification will contact you. You will be asked to correct and complete your application. Your application will be returned to you if you do not correct and complete the application within a reasonable period of time.
Step 4 - Estimate of costs
An estimated cost will be forwarded to you. The estimate is based on an hourly rate and will cover our assessment of:
- your certification plan
- witnessing of tests
- review of reports
- other essential activities.
An amount is also included to process and issue the STC. You will be advised at this time if you need to provide any further supporting documentation. You must pay the estimate and provide any further supporting documentation before we can commence work on your application.
A description of the estimate process is in our fees and charges section.
Note: If you wish to cancel the application at any time, notify Aircraft Certification in writing. We will recover costs for work completed up to the date of cancellation.
Step 5 - Assessment
Assessment time frames
The assessment time frames and the proposed certificate issue date is dependent on the:
- payment of the estimate or deposit
- quality of your documentation
- availability of our resources.
Step 6 - Recommendation
Once the assessment is complete, a recommendation to issue or not to issue the STC will be made to the CASA delegate.
If the approval varies from what you have applied for, or if the application is declined, we will discuss this with you.
Step 7 - Certificate issue
Aircraft Certification will reconcile the actual hours against the estimated hours for the assessment and either process a refund or raise an invoice for the additional costs. If approved, the STC will be faxed to you on the same day and the original forwarded by mail.
Our commitment to you
We will advise on:
- specific requirements and explain the application process to you
- proposed completion date
- changes to agreed timings or costs.
We will also keep track of your application from the day it is lodged to the day of the certificate issue.
We are authorised under section 27AA of the Civil Aviation Act 1988 to approve Form 733 and thereby collect the information you supplied in it. All such information received will be treated as being confidential. We are bound by the Privacy Act to safeguard personal information within the terms of that Act. We have a policy of publishing certificates on our website.