AD/B717/21 Fuel System Lightning Protection (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.

Boeing 717 Series Aeroplanes

AD/B717/21 Fuel System Lightning Protection 8/2007

Applicability:	Model 717-200 aeroplanes, as identified in Boeing Service Bulletin (SB) 717-28-0004, Revision 3, dated 21 June 2006.
Requirement:	1.    Replace the lightning critical clamp bases of the fuel tank vent system with improved clamp bases, in accordance with Table 1 of Figure 1 of the Accomplishment Instructions of SB 717-28-0004, Revision 3.
2.    Check the electrical bond of the modified self-bonding mounting clamps in accordance with the Accomplishment Instructions of the service bulletin.
3.    If any electrical bond fails the check, repair the electrical bond of the mounting clamp in accordance with the SB 717-28-0004, Revision 3; or according to a method approved by the Manager, Los Angeles Aircraft Certification Office (ACO), United States Federal Aviation Administration (FAA).  Chapter 28-00-00 of the Boeing 717 Aircraft Maintenance Manual and Chapter 20-50-01 of the Boeing DC, MD, and 717 Standard Wiring Practices Manual are one approved method.
Actions accomplished before the effective date of this Directive in accordance with Boeing SB 717-28-0004, Revision 2, dated 11 March 2005, are acceptable for compliance with the requirements of this Directive.
Later revisions of the above SB, approved by the FAA as an Alternate Method of Compliance (AMOC) to FAA AD 2006-20-12, are considered acceptable for compliance with the equivalent requirements of this Directive.
Note:  FAA AD 2006-20-12 Amdt 39-14782 refers.
Compliance:	For Requirement 1 - Within 68 months after the effective date of this Directive.
For Requirement 2 - Before further flight after the replacement of the clamp bases.
For Requirement 3 - Before further flight after the Requirement 2 check.
This Airworthiness Directive becomes effective on 2 August 2007.

Background: The FAA has advised that an investigation has revealed the aluminium foil strip on the nylon base of the ground clamps can fracture or separate from the base.  This Directive is issued to ensure that the fuel pipes are properly bonded to the aeroplane structure.  Improper bonding could prevent electrical energy from a lightning strike from dissipating to the aeroplane structure, which could result in a fuel tank explosion.

David Punshon
Delegate of the Civil Aviation Safety Authority

19 June 2007