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 747 Series Aeroplanes AD/B747/312 Fire Extinguisher System Tube 10/2004 Applicability: Model 747-400 and 747-400D series aeroplanes, as listed in Boeing Service Bulletin (SB) 747-26A2270, Revision 2 dated 26 June 2003. Requirement: Either inspect or pressure test the fire extinguishing system tube as detailed in Requirement 1 or 3 of this Directive. 1. Perform a detailed inspection of the fire extinguishing system tube and clamps for correct installation, either using an inspection hole and boroscope or with the floor panel removed, per Boeing SB 747-26A2270 Revision 2. If the fire extinguishing system tube is installed correctly no further action is required by this Directive. 2. If the fire extinguishing system tube is installed incorrectly, remove the fire extinguishing system tube and perform a detailed inspection of the fire extinguishing system tube for chafing/damage per Boeing SB 747-26A2270 Revision 2. 1. If no chafing/damage is found, install the existing fire extinguishing system tube per Figure 3 of Boeing SB 747-26A2270 Revision 2. b. If any chafing/damage is found, replace the fire extinguishing system tube with a new tube or repair the fire extinguishing system tube, per Boeing SB 747-26A2270 Revision 2, and install the new or repaired tube per Figure 3 of Boeing SB 747-26A2270 Revision 2. 3. Perform a pressure test of the fire extinguishing system tube to check for leakage of the fire-extinguishing agent per Boeing SB 747-26A2270 Revision 2. 4. If any leakage is found during the pressure test as detailed in Requirement 3 of this Directive, replace the fire extinguishing system tube with a new tube or repair the fire extinguishing system tube, per Boeing SB 747-26A2270 Revision 2, and install the new or repaired tube per Figure 3 of Boeing SB 747-26A2270 Revision 2. Note: FAA AD 2004-09-33 Amdt 39-13624 refers. Boeing 747 Series Aeroplanes AD/B747/312 (continued) Compliance: For Requirement 1: Unless previously accomplished, within 6,500 flight hours or 18 months from the effective date of this Directive, whichever occurs first. For Requirement 2: Prior to further flight following the completion of Requirement 1 of this Directive. For Requirement 3: Unless previously accomplished the initial inspection is to be carried out within 6,500 flight hours or 18 months from the effective date of this Directive, whichever occurs first, thereafter at intervals not to exceed 6,500 flight hours or 18 months, whichever occurs first, until the actions specified in Requirement 1, 2 or 4 of this Directive have been done. For Requirement 4: Prior to further flight following the completion of Requirement 3 of this Directive. This Airworthiness Directive becomes effective on 30 September 2004. Background: This Directive provides inspection requirements to prevent a chafed hole in the fire extinguishing system tube of the aft cargo compartment, which could result in a lack of fire extinguishing agent and consequent uncontained fire in the aft cargo compartment. Gary J Carr Delegate of the Civil Aviation Safety Authority 5 August 2004 The above AD is notified in the Commonwealth of Australia Gazette on 8 September 2004.