Staff Instruction (SI) No. 500-002

Approval of Airworthiness Limitations
- Regional Aircraft Certification Projects

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Issuing Office: Standards
Activity Area: Qualifying SI No.: 500-002
File No.: 5009-32-2 Issue No.: 02
RDIMS No.: 3826711 V6 Effective Date: 2008-02-12


1.1 Purpose

The purpose of this Staff Instruction (SI) is to provide procedural guidelines to be followed with respect to the approval of Airworthiness Limitations (AWL) associated with repairs and modifications.

1.2 Applicability

This document is applicable to Transport Canada Civil Aviation (TCCA) aircraft certification personnel and delegates.

1.3 Description of Changes

This document, formerly Staff Instruction (SI) 500-002 Issue 01, has been reissued as SI 500-002 Issue 02 to:

  1. incorporate changes to paragraph 4.0(a) to clarify the need for a Damage Tolerance Evaluation as per suggestions for amendment to SI 500-002 Issue 01, dated 2007-09-07 as submitted via the Transport Canada Civil Aviation Issues Reporting System (CAIRS) Tracking No. PL-6464;
  2. change Section 5.0 to include Regional Superintendents Aircraft Certification as per Aircraft Certification Management Team Meeting, Agenda Item#: A0801-20; and
  3. make minor editorial changes.


2.1 Reference Documents

It is intended that the following reference materials be used in conjunction with this document:

  1. Chapter 523 of the Airworthiness Manual (AWM) - Normal, Utility, Aerobatic and Commuter Category Aeroplanes;
  2. Chapter 525 of the AWM - Transport Category Aeroplanes;
  3. Chapter 527 of the AWM - Normal Category Rotorcraft;
  4. Chapter 529 of the AWM - Transport Category Rotorcraft;
  5. Chapter 533 of the AWM - Aircraft Engines;
  6. Chapter 535 of the AWM - Propellers;
  7. SI 513-007 - Approval of Modification and Repair Design;and
  8. Federal Aviation Administration Advisory Circular (FAA AC) No. 25-19 - Certification Maintenance Requirements.

2.2 Cancelled Documents

As of the effective date of this document, the following document is cancelled:

  1. Staff Instruction (SI) 500-002 Issue 01, dated 2007-09-07 - Approval of Airworthiness Limitations – Regional Aircraft Certification Projects.

2.3 Definitions and Abbreviations

The following definitions and abbreviations are used in this document:

  1. AWL means Airworthiness Limitations.
  2. CMR means Certification Maintenance Requirements.
  3. ICA means Instructions for Continued Airworthiness.
  4. LSTC means Limited Supplemental Type Certificate.
  5. RDC means Repair Design Certificate.
  6. STC means Supplemental Type Certificate.


  1. Some design change approval projects involve changes to, or the establishment of new, AWL that include mandatory structural inspections, component life limits, and mandatory system maintenance requirements such as CMR. Projects involving repairs or modifications to damage tolerant structures are an example of design changes, which may involve AWL.
  2. Changes to AWL, or the establishment of new AWL, require approval by TCCA. In the past, the Chief of Engineering, National Aircraft Certification was the only individual authorized to approve AWL.
  3. The references applicable to AWL are found in AWM:

    1. Section 523.1529 and Appendix G, Instructions for Continued Airworthiness;
    2. Section 525.1529 and Appendix H, Instructions for Continued Airworthiness;
    3. Section 527.1529 and Appendix A, Instructions for Continued Airworthiness;
    4. Section 529.1529 and Appendix A, Instructions for Continued Airworthiness;
    5. Section 533.4 and Appendix A, Instructions for Continued Airworthiness; and
    6. Section 535.4 and Appendix A, Instructions for Continued Airworthiness.


  1. AWL are established on the basis of approved engineering data. The approval of engineering data is to be done in accordance with the aircraft certification division of responsibilities for the project as established under the procedures of SI 513-007. The following aspects need to be considered when approving AWL:

    1. Certification Basis – New AWL are to be developed with engineering data that is consistent with the basis of certification of the product that is to be modified. In addition, a Damage Tolerance Evaluation may be required for modifications and repairs to fatigue critical baseline structure for transport category aeroplanes regardless whether the basis of the aeroplane pre-dates Federal Aviation Regulations (FAR) Part 25, Amendment 25-45. This would apply to the fatigue critical baseline structure where an Airworthiness Directive, Supplemental Inspection Document and/or Repair Assessment Guidelines is applicable. The Damage Tolerance Evaluation, where developed, would be included in the AWL.
    2. The ICA, including any AWL, need to be generated in a manner consistent with the Type Certification basis of the product as modified. For example, the provision of an AWL section, as part of ICA, was not required prior to FAR Part 25, Amendment 25-54.
    3. Format - AWL shall be contained in a supplement to the ICA in a section titled “Airworthiness Limitations” that is segregated and clearly distinguishable from the rest of the ICA. This section is to set forth each applicable mandatory replacement time, structural inspection interval and related structural inspection procedure, including all CMR associated with the design change. The ICA generated is to be in a format compatible with that published by the original equipment manufacturer.
    4. The AWL document must contain a legible statement in a prominent location that reads: “The Airworthiness Limitations section is approved by the Minister and specifies maintenance required by any applicable airworthiness or operating rule unless an alternative program has been approved by the Minister”. The name and office of the approving authority must appear adjacent to the approval statement.
    5. References - The approval certificate, STC, LSTC or RDC, must clearly reference any ICA and AWL generated for the project and must indicate that compliance with the AWL is mandatory. The approval certificate is the authoritative reference and is to take precedence.


  1. AWL associated with STC, LSTC or RDC projects may be approved by those holding the applicable internal Ministerial Delegation of Authority, which include:

    1. Chief of Engineering, National Aircraft Certification;
    2. Regional Manager Aircraft Certification; or;
    3. Regional Superintendent Aircraft Certification.
  2. The approval of extensions or modifications to existing AWL is subject to the following conditions:

    1. the existence of approved engineering data;
    2. a prior agreement by the Chief of Engineering, National Aircraft Certification, where it involves an extension to any AWL generated by the type certificate holder; and
    3. a prior agreement by the Chief of Continuing Airworthiness, National Aircraft Certification, where it involves AWL related to either mandatory airworthiness action, or an alternate means of compliance with any airworthiness directive.


For more information please contact:
Policy Standards Coordinator (AARTC)

Phone: 613-990-8234
Facsimile: 613-952-3298

Suggestions for amendment to this document are invited and should be submitted via the Transport Canada Civil Aviation Issues Reporting System (CAIRS) at the following Internet address:

or by e-mail at:

Original signed by J.-F. Mathieu

D.B. Sherritt
Director, Standards Branch
Civil Aviation

Date modified: