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/B737/230 Engine Fire extinguisher Squib Firing Circuit 11/2004 Applicability: Model 737-600, 737-700, 737-700C, 737-800 and 737-900 series aeroplanes, as listed in Boeing Alert Service Bulletin (ASB) 737-26A1118, Revision 1, dated 8 April 2004. Requirement: 1. Measure the electrical resistance of the dual ground studs of the support brackets for the fire extinguisher bottle located in the left main landing gear wheel well by accomplishing all actions specified in the Accomplishment Instructions of ASB 737-26A1118, Revision 1. 2. Correct any anomalies detected during the Requirement 1 resistance measurements. Actions accomplished before the effective date of this Directive in accordance with either Boeing Telex M-7200-02-01401, dated 9 September 2002 or ASB 737- 26A1118, dated 17 October 2002 are considered acceptable for compliance with the corresponding action specified in this Directive. Note: FAA AD 2004-18-02 Amdt 39-13779 refers. Compliance: For Requirement 1 - Within 90 days after the effective date of this Directive. For Requirement 2 - Before further flight after the Requirement 1 resistance measurements. This Airworthiness Directive becomes effective on 28 October 2004. Boeing 737 Series Aeroplanes AD/B737/230 (continued) Background: This Directive requires the measurement of the electrical resistance of the support bracket for the fire extinguisher bottle located in the left main landing gear wheel well to ensure that it does not exceed the maximum allowed resistance together with any necessary corrective action. This action is necessary to prevent high electrical resistance in the squib firing circuit, which could result in insufficient electrical current to fire the fire extinguisher bottle squib and discharge the fire extinguishing agent, which could lead to an uncontrolled engine fire. James Coyne Delegate of the Civil Aviation Safety Authority 16 September 2004 The above AD is notified in the Commonwealth of Australia Gazette on 6 October 2004.