Staff Instruction (SI) No. 500-001 Issue 2

Approval of Aeroplane Weight Changes

File No.:	5009-32-2	SI No.:	500-001
RDIMS No.:	2063396-V2	Issue No.:	02
Issuing Branch:	Aircraft Certification	Effective Date:	2006-11-15

1.0 Introduction

1.1 Purpose
1.2 Applicability
1.3 Description of Changes

2.0 References and Requirements

2.1 Reference Documents
2.2 Cancelled Documents

3.0 Background

4.0 Application Procedures

4.1 Aircraft Type Certification Holders
4.2 Other Persons
4.3 Required Coordination

5.0 Guidelines

6.0 Ferry Flights

7.0 Contact Office

1.0 Introduction

1.1 Purpose

The purpose of this Staff Instruction (SI) is to:

1. Provide approval procedures for aeroplane weight changes; and

2. Outline the coordination required between the Aircraft Certification and the Aircraft Maintenance and Manufacturing Branches.

1.2 Applicability

This document is applicable to Headquarters (HQ) and Regional Aircraft Certification personnel, including delegates. It is also applicable to the Aircraft Maintenance and Manufacturing Branch.  

1.3 Description of Changes

The content of this issue is unaltered with the exception of minor editorial changes and updated references.

2.0 References and Requirements

2.1 Reference Documents

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

1. Standard 507 of the Canadian Aviation Regulations (CAR)—Flight Authority and Certification of Noise Requirements;

2. Chapter 511 of the Airworthiness Manual (AWM)—Approval of the Type Design of an Aeronautical Product;

3. Chapter 513 of the AWM—Approval of Modification and Repair Designs;

4. Chapter 522 of the AWM—Gliders and Power Gliders;

5. Chapter 523-VLA of the AWM—Very Light Aeroplanes;

6. Chapter 523 of the AWM—Normal, Utility, Aerobatic and Commuter Category Aeroplanes;

7. Aircraft Maintenance and Manufacturing Staff Instruction (MSI) No. 45—Ferry Fuel System—Field Acceptance Criteria; and

8. Federal Aviation Administration (FAA) Advisory Circular (AC) No. 23-19—Airframe Guide for Certification of Part 23 Airplanes.

2.2 Cancelled Documents

Not applicable. 

3.0 Background

1. The approval of aeroplane weight changes above the maximum weight limits specified in their Type Certificate Data Sheet (TCDS) normally requires a multi-disciplinary evaluation.
2. For the purpose of this document the term “weight changes” applies to, but is not necessarily limited to, the following conditions:
    
   1. Maximum take-off weight;
   2. Maximum ramp weight;
   3. Maximum landing weight; and
   4. Maximum zero fuel weight.

4.0 Application Procedures

4.1 Aircraft Type Certification Holders

An application for a change in weight limitations submitted by a type certificate holder would normally be approved as a revision to the applicable TCDS as per Chapter 511 of the AWM.  Notwithstanding, a type certificate holder still has the option to apply for a Supplemental Type Certificate (STC) or a Limited Supplemental Type Certificate (LSTC) in accordance with the procedures in Chapter 513 of the AWM.

4.2 Other Persons

An application submitted by a person other than the type certificate holder is to be reviewed in accordance with the procedures in Chapter 513 of the AWM and, subject to a satisfactory evaluation, may culminate in the issuance of an STC or an LSTC. The application may require engineering support from the responsible type certificate holder.

4.3 Required Coordination

The responsible region should consult the HQ Flight Test Division specialists at the start of a program, where the proposed change in maximum weight will result in a conflict with those operating limitations specified in the aeroplane TCDS.   

5.0 Guidelines

1. Any application for the approval of weight increases above the maximum limits specified in the TCDS requires a comprehensive technical evaluation and substantiation. The evaluation should address:
    
   1. All applicable static and dynamic loads;
   2. Possible changes to controllability, static and dynamic stability, including flutter, must be considered;
   3. Changes in aeroplane performance due to the weight change must be investigated and validated. A flight evaluation is normally required to achieve these objectives;
   4. A fatigue assessment (safe-life, fail-safe, flaw tolerant or damage tolerance or a combination thereof, as applicable) is normally required. The fatigue assessment must take into account any changes in the operational role; and
   5. An analysis of the impact on emergency landing should also be performed based on the weight change.
2. The applicant should define the load spectrum(s) based upon the anticipated usage. The effect of a potential change in load spectra should be evaluated and adjustments to the airframe inspection intervals made accordingly. It is noteworthy that relatively minor changes in spectra stress levels may result in large reductions in the fatigue life or mandatory inspection intervals.
3. Where the aeroplane weight change exceeds the weight limitations specified for the undercarriage, compliance with the applicable requirements for the undercarriage and supporting structure must be shown.  These include, but may not be limited to: 
    
   1. Shock absorption tests, tire rating;
   2. Undercarriage fatigue qualifications;
   3. Brake energy capacity and fatigue spectra changes to the aeroplane structure due to dynamic taxi effects; and
   4. A fatigue assessment (safe-life, fail-safe, flaw tolerant or damage tolerance or a combination thereof, as applicable) is normally required.
4. The impact of weight changes to the Aircraft Flight Manual (AFM), Instructions for Continued Airworthiness and the Weight and Balance Report, among others, should be investigated.
5. Due to the complexity of the requirements associated with a transport category aeroplane, demonstration of compliance is expected to be significantly more involved.  FAA AC No. 23-19 provides guidance on structural substantiation concerning the approval of weight increases on Federal Aviation Regulations Part 23 aeroplanes.

6.0 Ferry Flights

Requests submitted for aeroplane weight increases associated with ferry flights for the purpose of importation or exportation as described in subsection 507.04(3) of the CAR, may be approved by the regions subject to the following conditions:

1. A required gross weight increase above ten percent (10%) for the categories of aeroplane mentioned above or for any other category of aircraft requires an approval by the region subject to prior consultation with the HQ Flight Test Division specialists.
2. The approved weight must be specified on the flight permit, or other approval document (e.g. AFM Supplement).

7.0 Contact Office

For more information please contact:

Policy Standards Coordinator (AARDH/P)
Phone: (613) 990-8234
Facsimile: (613) 996-9178
E-mail: AARDH-P@tc.gc.ca

Original signed by Gilles Morin

Gilles Morin
Chief, Regulatory Standards
Aircraft Certification Branch