Repair Design Approval
Learn about the Repair Design Approval (RDA) required to design repairs for incorporation on Singapore-registered aircraft, its associated engines, propellers or articles.
Last updated 14 May 2026
What is a Repair Design Approval
A Repair Design Approval (RDA) is issued to approve a major repair design that restores an aircraft, engine, propeller or article to its approved type design and an airworthy condition.
What are major repair designs
A major repair to an aircraft, engine, propeller or article is a repair that has a significant effect on one or more of the following:
mass
balance
structural strength
performance
engine operation
flight characteristics
other qualities affecting airworthiness or environmental characteristics
Note:
Major repair designs to Singapore-registered aircraft must be approved by CAAS through the issuance of a Repair Design Approval (RDA).
Minor repair designs 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 Repair Design Approval.
Application process
Who can apply
Applications may be submitted by CAAS Design Organisation Approval (DOA) holders with an approved scope to carry out aircraft repair design activities.
How to qualify
Before CAAS can process the application for the RDA, the aircraft design must first have been accepted by CAAS through the issuance of the Letter of Acceptance of Type Certificate.
The repair design 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 F of the SAR-21.
When to apply
Applications should be submitted when major repair designs are to be incorporated on Singapore‑registered aircraft or their associated engines, propellers, or articles.
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 RDA application to facilitate timely processing.
How to apply
Phase 1: Pre-application
The applicant meets with CAAS to provide details of the repair design, and better understand the application process.
Phase 2: Formal application
The applicant submits the application with all required supporting documents as stated in SAR-21 AMC 21.505(a), which includes details of:
the aircraft, engine, propeller or article
the damage
the proposed repair design
compliance with the applicable airworthiness design requirements
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 find compliance to the relevant airworthiness design standards through participation in 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 Repair Design Approval upon receipt of payment.
Application for Repair Design Approval
To apply, please contact us. An officer will guide you through the application process.
What is the validity period
The RDA remains effective until it is surrendered by the holder or cancelled by CAAS.
Legislation, regulations and resources
Contact information
Flight Standards Division
Contact us using the Enquiries & Feedback Form.