Advisory Circular (AC) No. 500-007 Issue 1

Lightning Protection Of Aircraft Fuel Systems

File No. 5009-6-500 AC No. 500-007
RDIMS No. 528248-V2 Issue No. 01
Issuing Branch National Aircraft Certification Effective Date 2004-12-01

1.0 Introduction

1.1 Purpose
1.2 Guidance Applicability
1.3 Description of Changes
1.4 Termination

2.0 References

2.1 Reference Documents
2.2 Cancelled Document

3.0 Background

4.0 Acceptable Means Of Compliance

5.0 Headquarters Contact

1.0 Introduction

1.1 Purpose

The purpose of this Advisory Circular (AC) is to provide guidance material for an acceptable means, but not the only means, of demonstrating compliance with the lightning strike requirements of sections 523.954, 525.954, 527.954 and 529.954 of the Airworthiness Manual (AWM).

1.2 Guidance Applicability

This document is applicable to all Transport Canada personnel, delegates and industry.

1.3 Description of Changes

This document, formerly AMA No. 500C/6, is reissued as an AC. With the exception of minor editorial changes and updated references, the content is unaltered.

1.4 Termination

This document does not have a terminating action. It will however, be reviewed periodically for suitability of content.

2.0 References

2.1 Reference Documents

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

(a) Chapter 523 of the Airworthiness Manual (AWM) - Normal, Utility, Aerobatic and Commuter Category Aeroplanes;
 
(b) Chapter 525 of the AWM - Transport Category Aeroplanes;
 
(c) Chapter 527 of the AWM - Normal Category Rotorcraft;
 
(d) Chapter 529 of the AWM - Transport Category Rotorcraft;
 
(e) Federal Aviation Administration Advisory Circular (FAA AC) 20-53 - Protection of Aircraft Fuel Systems Against Lightning;
 
(f) FAA AC 20-53A - Protection of Airplane Fuel Systems Against Fuel Vapor Ignition Due to Lightning;
 
(g) U.S. Department of Transportation, Federal Aviation Administration (FAA) Technical Center Report No. DOT/FAA/CT-83/3 - User's Manual for AC 20-53A, Protection of Airplane Fuel Systems Against Fuel Vapor Ignition Due to Lightning; and
 
(h) Society of Automotive Engineers (SAE) Report of SAE Committee AE4L - Lightning Test Waveforms and Techniques for Aerospace Vehicles and Hardware.

2.2 Cancelled Document

As of the effective date of this document, AMA No. 500C/6 dated 27 October 1989 is cancelled.

3.0 Background

The airworthiness standards require that aircraft fuel systems be designed and arranged to prevent the ignition of fuel vapour within the system as a result of a lightning strike. Table 1 of FAA AC 20-53 defined minimum material thickness in areas defined as Zone 1, i.e. areas of probable lightning strike initial attachment. However, Table 1 of FAA AC 20-53 did not make recommendations for minimum material thickness in areas defined as Zone 2, swept stroke zone. As a result, different interpretations were made by airframe manufacturers as to the protection necessary for Zone 2.

4.0 Acceptable Means Of Compliance

FAA AC 20-53A is acceptable for showing compliance with the airworthiness requirements referenced in section 1.1 when applied in accordance with the following conditions:

(a) Integral fuel tanks, located in Zone 2 defined lightning strike areas, having aluminum skin thickness less than .080 inches shall be subject to lightning strike evaluation in accordance with procedures established in the Report of SAE Committee AE4L entitled "Lightning Test Waveforms and Techniques for Aerospace Vehicles and Hardware".
 
The FAA document entitled "User's Manual for AC 20-53A, Protection of Airplane Fuel Systems Against Fuel Vapor Ignition Due to Lightning" is considered to be acceptable guidance material, in accordance with procedures established in Report Number DOT/FAA/CT-83/3, provided that the example for determination of aluminum skin thickness given in 6.1 is strictly followed. Interpolation between curves shown in figure 12 for skin thickness is not acceptable.
 
(b) Lightning protection shall be provided to other components of the fuel system as prescribed by FAA AC 20-53A, supplemented by the FAA "User's Manual for AC 20-53A, Protection of Airplane Fuel Systems Against Fuel Vapor Ignition Due to Lightning".

5.0 Headquarters Contact

For more information please contact:

Policy Standards Coordinator (AARDH/P)
Phone: (613) 990-3923
Facsimile: (613) 996-9178
E-mail: AARDH-P@tc.gc.ca

Original signed by Maher Khouzam

Maher Khouzam
Chief, Regulatory Standards
National Aircraft Certification Branch

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