ATSB releases final Ansett 767 safety investigation report
The Australian Transport Safety Bureau has released its final report after an almost two-year investigation of the systemic factors behind the groundings of Ansett B767 aircraft.
While Ansett has ceased flying, the ATSB continued its investigation because of the importance of the issues involved for the safety of 'Class A' aircraft around the world.
The ATSB found that in addition to errors and omissions by individuals in Ansett, there were deeper system and resource weaknesses in the airline group and shortcomings by the US regulator of the aircraft type (the FAA) both of which CASA was unaware.
The Boeing 767 aircraft was among the first in the world to be designed and certified under damage tolerance principles. This meant that while some aircraft structural fatigue cracking was expected, a robust system for regular inspection and maintenance was essential to assure continuing airworthiness.
Ansett omitted to action 25,000 flight cycle inspections issued by Boeing in June 1997 and updated in June 2000 to include fatigue crack inspections of the aircraft tail. It also failed to action within the recommended six months a March 2000 Boeing 'Alert' service bulletin relating to possible cracking in B767 engine mount fittings.
The FAA did not mandate Boeing's June 1997 inspections and subsequent service bulletins until after the second Ansett groundings in April 2001. Boeing did not highlight the potential safety significance of the tail cracking issue in its service bulletin until November 2001 - prior to this Boeing's focus was on it being a commercial issue.
The former CAA had reduced the Australian regulator's in-house capacity to review important safety service bulletins and relied on foreign regulators like the FAA and operators like Ansett to do so. CASA was unaware of delays in the FAA and did not appreciate the extent of problems involving Ansett's maintenance. Vulnerability was compounded by weaker than desirable feedback systems for maintenance issues.
The action by Ansett and CASA to ground the B767 aircraft until safety could be assured protected the flying public. The ATSB issued two recommendations in April 2001. CASA also conducted an extensive review and is addressing its findings.
The ATSB is today making a further 11 recommendations to ICAO, the FAA, and CASA designed to augment the safety defences for Class A aircraft such as the B767.
The Ansett 767 maintenance case highlights the need for organisations to be continually mindful of potential threats to aviation safety, particularly when commercial pressures intensify and there are significant changes to structures and the broader environment.Media contact: 1800 020 616 Last update 01 April 2011