AD/B737/239 Engine Fuel Feed System 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.

Boeing 737 Series Aeroplanes

AD/B737/239 Engine Fuel Feed System Electrical Bonding 5/2005

Applicability:	Model 737-100, -200, -200C, -300, -400 and -500 series aeroplanes identified in Boeing Service Bulletin (SB) 737-28A1174, Revision 1, dated 18 July 2002.
Requirement:	1.    Action in accordance with paragraph 3.B. of SB 737-28A1174, Revision 1.
2.    Carry out any necessary corrective actions on deficiencies detected during the accomplishment of Requirement 1.
Note 1:  Operators may use their own CASA accepted equivalent procedures for draining the fuel tanks and gaining access to the fuel tanks.
Note 2:  The marking of the forward surface of the front spar in accordance with SB 737-28A1174, Revision 1, Figures 1 and 2, Step 18, is not required for compliance with this Directive.
Note 3:  Actions accomplished before the effective date of this Directive in accordance with Boeing SB 737-28A1174 dated 20 December 2001 are acceptable for compliance with this Directive.
Note 4:  FAA AD 2005-04-01 Amdt 39-13973 refers.
Compliance:	For Requirement 1 - Before 12 May 2010.
For Requirement 2 - Before further flight after accomplishing Requirement 1.
This Airworthiness Directive becomes effective on 12 May 2005.

Background: The United States Federal Aviation Administration has determined that is necessary to reduce the potential for ignition sources inside fuel tanks.  This Directive is issued to prevent arcing or sparking at the interface between the bulkhead fittings of the engine fuel feed tube and the front spar inside the fuel tank of the wings and between the overwing fuel fill ports and the aeroplane structure during a lightning strike.  Such arcing or sparking could provide a possible ignition source for the fuel vapour inside the fuel tank and cause consequent fuel tank explosions.

James Coyne
Delegate of the Civil Aviation Safety Authority

31 March 2005