Supplemental Type Certificate
Learn about the Supplemental Type Certificate required for incorporating major modification to aircraft registered in Singapore.
Last updated 14 May 2026
What is a Supplemental Type Certificate
A Supplemental Type Certificate (STC) is issued to approve a major modification to an aircraft’s approved design.
What are major modifications
A major modification to an aircraft is a change to the approved type design that has a significant effect on one or more of the following:
mass and balance limits
structural strength
engine operation
flight characteristics
reliability
operational characteristics
other qualities affecting airworthiness or environmental characteristics
Note: Minor modifications may be approved in accordance with the privileges of CAAS Design Organisation Approval (DOA) holders.
Mutual recognition
CAAS has established bilateral agreements with other Civil Aviation Authorities on the processing of Supplemental Type Certificate (STC) approvals.
Application process
Who can apply
Applications may be submitted by CAAS Design Organisation Approval (DOA) holders with an approved scope to carry out aircraft modification design activities.
How to qualify
Before CAAS can process the application for the STC, the aircraft design must first have been accepted by CAAS through the issuance of the Letter of Acceptance of Type Certificate.
The design changes to the aircraft must meet the applicable airworthiness design standards stated in the Singapore Airworthiness Requirements Part 21 (SAR-21).
Further information on the requirements may be found in Subpart C of the SAR-21.
When to apply
Applications should be made when major modifications are to be incorporated on Singapore-registered aircraft.
You are encouraged to engage CAAS early to facilitate planning and ensure sufficient time for the review and acceptance process.
What are the fees
The fees payable are stated in:
What is the processing time
Processing timelines vary by application type and are set out in IC 6/2025 Information circular on service standards for processing of aviation safety instruments related to airworthiness, flight operations and training organisations.
You are encouraged to engage CAAS early to discuss your STC application to facilitate timely processing.
How to apply
Phase 1: Pre-application
The applicant meets with CAAS to provide modification details and better understand the application process.
Phase 2: Formal application
The applicant submits the application with all the required documents as stated in SAR-21 AMC 21.305(a), which includes:
CAAS(AW)212 application form
the letter of intent from Singapore air operator
certification plan
details of the applicable certification basis
Phase 3: Document evaluation
CAAS reviews the application and supporting documents, and notifies the applicant on the level of CAAS involvement in compliance demonstrations.
Phase 4: Demonstration and inspection
CAAS verifies compliance with the relevant airworthiness design standards through certification activities, such as conformity inspections and test witnessing.
Phase 5: Certification
Once compliance with all applicable airworthiness design requirements has been confirmed, CAAS will issue an invoice for all applicable fees and will issue the STC upon receipt of payment.
Application for STC
To apply, please contact us. An officer will guide you through the application process.
What is the validity period
The STC remains effective until it is surrendered by the holder or cancelled by CAAS.
STCs issued by CAAS
For a list of STCs issued, download Supplemental Type Certificates issued.
Legislation, regulations and resources
Contact information
Flight Standards Division
Contact us using the Enquiries & Feedback Form