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.