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Civil Aviation Authority of Singapore

Design Organisation Approval

Learn about the approval required to design articles, modifications, and repairs for Singapore registered aircraft.

Last updated 14 May 2026

Who can apply 

Singapore or overseas organisations that want to design articles, modifications or repairs for Singapore-registered aircraft. 

Application process 

How to qualify 

You must meet the requirements under Singapore Airworthiness Requirements (SAR) Part 21, Subpart H. 

For instance, you must: 

  • submit a letter of intent

  • show the need for your services from any one of the following:

    • a Singapore air operator

    • a SAR-145 Approved Maintenance Organisation (AMO)

  • set up a design control system: 

    • how designs and design changes are managed and approved 

    • appointment of design signatories (staff) authorised to certify data 

    • details on how the designs comply with the requirements 

    • quality assurance and internal audit procedures  

  • Collaborate with production organisations to ensure integrity, and provide continued airworthiness instructions where applicable

Design organisations based outside of Singapore

Organisations based outside of Singapore holding design approvals issued by partner Authorities may produce articles for Singapore-registered aircraft under a bilateral arrangement, such as a Technical Arrangement on Airworthiness Certification (TA-AC).

When to apply 

You must apply for approval before:

  • you undertake design activities on Singapore-registered aircraft

  • when entering into a DO-PO arrangement  

Holding a Design Organisation Approval (DOA) is a pre-requisite if you intend to apply for: 

  • Supplemental Type Certificate (STC)

  • Singapore Technical Standard Order (STSO)

  • Repair Design Approval (RDA) 

What are the fees

The fees payable are stated in the Air Navigation Order (ANO) Twelfth Schedule.

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 Design Organisation Approval application to facilitate timely processing.

How to apply 

Phase 1: Pre-application 

  1. Have your Quality Manager (or equivalent) meet with us to learn more about the process before applying. You may contact us using our Enquiries & Feedback Form.

    The application should be made via the online application eSOMS. Forms stated in Phase 2 should only be used in the case of prolonged system downtime of eSOMS

    Note: CAAS will assign an officer to guide you through the application process.

Phase 2: Formal application

  1. Fill in and submit your application on eSOMS together with the required documents. The required documents are:

    • letter of application addressed to CAAS' Director of Flight Standards Division

    • letter of intent (either a Singapore Air Operator or a SAR-145 Approved Maintenance Organisation (AMO))

    • SAR-21 approval application (use Form CAAS(AW)21B if eSOMS is not available)

    • personnel resume of accountable manager, senior person responsible for quality assurance and design signatory (use Form CAAS(AW)22 if eSOMS if not available)

    • nomination form for design signatory (use Form CAAS(AW)102A if eSOMS is not available)

    • proposed Design Organisation Exposition describing your organisation, key personnel, resources, scope of design, conformity methods, and procedures

    • documentation showing that you have obtained the appropriate facilities for the scope of work (e.g. lease agreement)

    • company registration (for Singapore company, please provide ACRA or its equivalent)

    • any proposed manual (as applicable)

    • personnel training programmes 

    • a Statement of Compliance for each applicable paragraph of SAR-21

    • a Schedule of Events with estimated timelines for the approval process 

If eSOMS is not available, download and submit CAAS(AW)21B Application form for SAR-21 Approval Organisation. 

Note: The application process will only start once the complete set of documents is received.

Phase 3: Document evaluation

  1. CAAS reviews your application documents to ensure that your processes and procedures comply with SAR-21. 

    During this phase, CAAS may request for clarifications and amendments of the submitted documents. 

Phase 4: Demonstration and inspection

  1. CAAS interviews your staff and audits your facilities to verify that you have the required staff, resources and processes. 

Phase 5: Certification

  1. You will receive your DOA certificate once CAAS has verified that you comply with all of the requirements under SAR-21, and upon successful completion of payment. 

  2. After certification, CAAS conducts regular inspections to ensure certificate holders continue to meet safety and regulatory standards.

Application for DOA

To apply, please contact us. An officer will be assigned to guide you through the application process.

Contact CAAS

What is the validity period  

An organisation approval is usually valid for 1 year from the date of issue unless surrendered, superseded, suspended or revoked. 

To renew your DOA, submit your application 5 weeks to 2 months before expiry. 

Design organisations  

You can download the following lists which are updated monthly: 

Legislation, circulars and advisories 

Contact information 

Flight Standards Division
Contact us using the Enquiries & Feedback Form.