COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Piper PA-46 (Malibu) Series Aeroplanes AD/PA-46/23 Amdt 1 Vacuum Gauge Marking 10/93 Applicability: PA-46-310P Malibu aircraft serial numbers 46-8408001 to 46-8608067 inclusive and 4608001 to 4608140 inclusive. PA-46-350P Malibu Mirage aircraft serial numbers 4622001 to 4622118 inclusive. Requirement: Install vacuum gauge marking in accordance with Part II of Piper Service Bulletin 947A dated 29 October 1991. Note: FAA AD 92-15-14 refers. Compliance: The previous compliance was within 100 hours time in service from 17 September 1992. The compliance for this issue is within 100 time in service from 16 September 1993. Background: The FAA has received a report of aircraft experiencing in-flight vacuum system failures, the failures went undetected because the low vacuum detector failed to sense a low vacuum and the vacuum gauge did not display a safe operating range. Compliance with this Directive, whilst not preventing in-flight failures of the vacuum system, allows for early detection of the failures, thus preventing failure of the air- driven attitude gyro and autopilot systems caused by undetected low vacuum. This amendment is issued to correct a typographical error in the applicability statement which incorrectly limited the PA-46-310P serial number range.