AD/B737/330 Boost Pump Control Relay Ground Block Corrosion (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/B737/330 Boost Pump control Relay
Ground Block Corrosion 7/2008

Applicability:	Model 737-600, -700, -700C, -800 and -900 series aeroplanes, as identified in Boeing Special Attention Service Bulletin 737-28-1257, Revision 1, dated 28 November 2007.
Requirement:	1.    Carry out a general visual inspection of ground blocks GD261 and GD264 for corrosion, measure the electrical bond resistance and separate the ground wires for the fuel boost pump circuit between ground blocks GD261 and GD264 in accordance with the Accomplishment Instructions of Boeing Special Attention Service Bulletin (SB) 737-28-1257, Revision 1, dated 28 November 2007.
2.    Rectify any discrepancies detected during any inspection, measurement or any other action, carried out in accordance with Requirement 1, in accordance with SB 737-28-1257, Revision 1.
Actions accomplished before the effective date of this Directive in accordance with SB 737-28- 1257, dated 26 February 2007, are acceptable for compliance with the corresponding requirements of this Directive.
Later revisions of SB 737-28-1257, approved by the United States Federal Aviation Administration (FAA) as an Alternate Method of Compliance (AMOC) to FAA AD 2008-09-14, are considered acceptable for compliance with the equivalent Requirements of this Directive.
Note:  FAA AD 2008-09-14 Amdt 39-15495 refers.
Compliance:	For Requirement 1 - Within 24 months after the effective date of this Directive.
For Requirement 2 - Before further flight after complying with Requirement 1.
This Airworthiness Directive becomes effective on 3 July 2008.
Background:	The United States Federal Aviation Administration (FAA) has received a report of random flashes of the six fuel pump low pressure lights and intermittent operation of the fuel boost pumps.  We are issuing this AD to prevent the simultaneous malfunction of all six fuel boost pumps, which could cause the engines to operate on suction feed and potentially flame out.

This Directive requires inspecting ground blocks GD261 and GD264 for corrosion, measuring the electrical bond resistance between the ground blocks and the aeroplane structure, separating the ground wires for the fuel boost pump circuit between ground blocks GD261 and GD264 and, if necessary, carrying out corrective actions if necessary.

James Coyne
Delegate of the Civil Aviation Safety Authority

22 May 2008