AD/B737/345 Fuel Tank Safety (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/B737/345 Fuel Tank Safety 13/2008

Applicability:	Model 737-600, -700, -800 and -900 series aeroplanes, as identified in Boeing Alert Service Bulletin (ASB) 737-28A1221, Revision 1, dated 9 November 2007.
Requirement:	1.    Install the hot short protector (HSP) support brackets and equipment for the fuel quantity indicating system (FQIS) fuel densitometer and do all the other specified actions as applicable, by accomplishing all of the applicable actions specified in the Accomplishment Instructions of ASB 737-28A1221, Revision 1.
Actions accomplished before the effective date of this Directive in accordance with ASB 737-28A1221, dated 14 January 2007, are acceptable for compliance with the Requirement 1.
2. Revise the Airworthiness Limitations (AWL) section of the Instructions for Continued Airworthiness (ICA) by incorporating AWL No. 28-AWL-07 of Subsection F, "AIRWORTHINESS LIMITATIONS-FUEL SYSTEM AWLs,'' of Section 9 of the Boeing 737-600/700/800/900 Maintenance Planning Data (MPD) Document, D626A001-CMR, Revision March 2007 R2 (hereafter referred to as "the MPD'').
Incorporating AWL No. 28-AWL-07 into the AWLs section of the ICA in accordance with Requirement 1.c. of AD/B737/329 (paragraph (g)(3) of United States Federal Aviation Administration (FAA) AD 2008-10-10), terminates the action required by Requirement 2.
3.    No alternative Critical Design Configuration Control Limitations (CDCCL) may be used unless the CDCCLs are approved as an alternative method of compliance (AMOC) by the Manager, Seattle Aircraft Certification Office, FAA.
Later revisions of ASB 737-28A1221, approved by the FAA as an AMOC to FAA AD 2008-17-15, are considered acceptable for compliance with the equivalent Requirements of this Directive.
Note:  FAA AD 2008-17-15 Amdt 39-15653 refers.
Compliance:	For Requirement 1 - Within 60 months after the effective date of this Directive.
For Requirement 2 - Concurrently with accomplishing the Requirement 1 actions.

For Requirement 3 - After accomplishing the action specified in Requirement 2.
This Airworthiness Directive becomes effective on 18 December 2008.
Background:	This Directive results from fuel system reviews conducted by the manufacturer.  The Directive is issued to prevent the centre tank fuel densitometer from overheating and becoming a potential ignition source inside the centre fuel tank which, in combination with flammable fuel vapours, could result in a centre fuel tank explosion and consequent loss of the aeroplane.

James Coyne
Delegate of the Civil Aviation Safety Authority

6 November 2008