COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Boeing 747 Series Aeroplanes AD/B747/175 Amdt 1 Door Switch Replacement 4/98 Applicability: All B747 -100, -200 and -300 series aeroplanes as listed in Boeing Alert Service Bulletin (ASB) 747-33A2252 Revision 2 dated 4 December 1997. Requirement: 1. Replace switches S4 and/or S5 or S7 and S8, as applicable, that are installed in the cabin attendant's panel, at Door 4 right, and the equivalent switches at Door 2 right with new items in accordance with the procedures specified in Boeing ASB 747- 33A2252 Revision 2. 2. Switches, having part numbers identified in the 'Old Switch' column of any table contained in Boeing ASB 747-33A2252 Revision 2 shall not to be installed at Door 2 Right or at Door 4 Right of any aeroplane. Note: FAA AD 97-08-05 Amdt 39-9993 refers. Compliance: 1. Prior to 26 April 1998. 2. Subsequent to 26 March 1998. This amendment becomes effective on 26 March 1998. Background: Amendment 1 to this AD changes the Boeing Service Bulletin reference. The original reference did not detail the procedure for door 2 Right. Reports have been received by the FAA that fires have occurred on some aeroplanes due to the internal failure of some of these switches. The actions specified by this AD are intended to prevent the installation and use of switches that could short circuit when they fail, and consequently cause smoke and fire aboard the aeroplane. The original issue of this airworthiness directive became effective on 19 June 1997.