AD/CL-600/90 Fuel Line Couplings (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-600/90 Fuel Line Couplings 13/2007

Applicability:

Bombardier Inc. Model CL-600-2B19 aircraft, serial numbers 7003 through 7067, and 7069 through 7981.

Requirement:

Replace the fuel tube couplings inside the wing and centre fuel tanks with redesigned couplings, according to the Accomplishment Instructions of Bombardier Service Bulletin (SB) 601R-28-054, Revision A, dated 7 August 2006, or later revisions approved by the Chief, Continuing Airworthiness, Transport Canada.

Note:  Transport Canada AD CF-2007-23 dated 18 October 2007 refers.

Compliance:

Within 5000 flight hours after the effective date of this AD.

This Airworthiness Directive becomes effective on 20 December 2007.

Background:

Bombardier Aerospace has completed a system safety review of the CL-600-2B19 aircraft fuel system against new fuel tank safety standards, introduced in Chapter 25 of the Transport Canada Airworthiness Manual through Notice of Proposed Amendment (NPA) 2002-043.  The identified non-compliances were assessed using Transport Canada Policy Letter No. 525-001 to determine if mandatory corrective action is required.

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 or excessive axial clearance at the reducer ferrules of certain 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 AD mandates the replacement of certain fuel tube couplings with redesigned couplings.

David Punshon
Delegate of the Civil Aviation Safety Authority

25 October 2007