AD/B737/236 Centre Fuel Tank FQIS Wire Bundle (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 39.1 (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/B737/236 Centre Fuel Tank FQIS Wire Bundle 2/2005

Applicability:	Boeing Model 737-600, -700, -800 and -900 series aeroplanes, as listed in Boeing Special Attention Service Bulletin (SB) 737-28-1190, Revision 1, dated 27 March 2003.
Requirement:	1.    Replace the centre fuel tank wire support bracket for the Fuel Quantity Indication System (FQIS) wire bundle with a new, improved bracket, in accordance with SB 737-28-1190, Revision 1.
2.    Perform a general visual inspection of the FQIS wire bundle for damage as specified in the Accomplishment Instructions of SB 737-28-1190, Revision 1.
Note 1:  For the purposes of this Directive, a general visual inspection is defined as: "A visual examination of an interior or exterior area, installation, or assembly to detect obvious damage, failure, or irregularity.  This level of inspection is made from within touching distance unless otherwise specified.  A mirror may be necessary to enhance visual access to all exposed surfaces in the inspection area.  This level of inspection is made under normally available lighting conditions such as daylight, hangar lighting, flashlight, or droplight and may require removal or opening of access panels or doors.  Stands, ladders, or platforms may be required to gain proximity to the area being checked."
3.    If any damage to the wire bundle is noted during the Requirement 2 visual inspection, repair or replace the damaged wire bundle in accordance with the Accomplishment Instructions of SB 737-28- 1190, Revision 1.
Actions accomplished before the effective date of this Directive in accordance with Special Attention Service Bulletin 737-28- 1190, dated 16 January 2003, are considered acceptable for compliance with the corresponding action specified in this Directive.
4.    FQIS wire bundle bracket part number 287A9111-3 may not be installed on any aeroplane as a replacement part.
Note 2:  FAA AD 2004-24-07 Amdt 39-13883 refers.
Compliance:	For Requirement 1 - Within 24 months after the effective date of this Directive.

For Requirement 2 - Concurrent with Requirement 1.

For Requirement 3 - Before further flight after the Requirement 2 inspection.

For Requirement 4 - As of the effective date of this Directive.

This Airworthiness Directive becomes effective on 17 February 2005.

Background:

The United States Federal Aviation Administration has found an incorrectly installed FQIS wire bundle during an audit.  This Directive requires the replacement of the bracket for the wire bundle of the FQIS, performance of a general visual inspection of the FQIS wire bundle for damage and, if necessary, any corrective action.

The Directive is issued to prevent chafing of the FQIS wire(s) in the centre fuel tank, which, when combined with a lightning strike or a power wire short to the FQIS wire(s), could result in arcing in the centre fuel tank and consequent fuel tank explosion.

James Coyne
Delegate of the Civil Aviation Safety Authority

23 December 2004

The above AD is notified in the Commonwealth of Australia Gazette on 26 January 2005.