AD/CL-600/100 Fuel Tube Coupling Electrical Bonding (Cth)

AIRWORTHINESS DIRECTIVE

For the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.001(1) of CASR 1998.  The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.

Bombardier (Canadair) CL-600 (Challenger) Series Aeroplanes

AD/CL-600/100 Fuel Tube Coupling - Electrical Bonding 7/2008

Applicability:

Bombardier Inc. Model CL-600-2C10 aircraft, serial numbers 10003 through 10169 and CL-600-2D24 aircraft, serial numbers 15001 through 15025.

Requirement:

1.    For aircraft that have not incorporated the original issue of Bombardier Service Bulletin (SB) 670BA-28-014, replace the fuel tube couplings inside the wing and centre fuel tanks with redesigned couplings, according to Part A of the Accomplishment Instructions of Bombardier SB 670BA-28-014, Revision A, dated 7 May 2007, or later revisions approved by the Chief, Continuing Airworthiness, Transport Canada.

2.    For aircraft that have already incorporated the original issue of Bombardier SB 670BA-28-014, inspect the aft scavenge ejector fuel couplings inside the LH and RH wing fuel tanks and replace with redesigned couplings if necessary, according to Part B of the Accomplishment Instructions of Bombardier SB 670BA-28-014, Revision A, dated 7 May 2007, or later revisions approved by the Chief, Continuing Airworthiness, Transport Canada.

Note:  Transport Canada AD CF-2008-02 dated 3 January 2008 refers.

Compliance:

Within 4500 hours flight time after the effective date of this directive.

This Airworthiness Directive becomes effective on 3 July 2008.

Background:

Bombardier Aerospace has completed a system safety review of the
CL-600-2C10/CL-600-2D24 aircraft fuel system against new fuel tank safety standards.

The assessment and lightning tests showed that certain fuel tube self-bonded couplings do not provide sufficient lightning current capability.  The assessment also showed that single failure of the integral bonding wire of the self-bonded couplings could affect electrical bonding between fuel tubes.

Insufficient electrical bonding between fuel tubes or insufficient current capability of fuel tube couplings, if not corrected, could result in arcing and potential ignition source inside the fuel tank during lightning strikes and consequent fuel tank explosion.  To correct the unsafe condition, this directive mandates the replacement of certain fuel tube couplings with redesigned couplings.

James Coyne
Delegate of the Civil Aviation Safety Authority

22 May 2008