By MATHEW DEARNALEY
Investigators are about six weeks from issuing their final report into an engine blowout on an Air New Zealand plane above Brisbane.
The Australian Transport Safety Bureau's report on the blowout, which forced a Boeing 767 to return to Brisbane for an emergency landing on December 8, should close off the last of a series of major investigations into incidents involving the airline from May 2001.
It will follow a comparison of results from metallurgical tests conducted both by bureau agents and by United States engine-maker General Electric on surviving parts from a turbine disc which broke free, punching a hole in the engine casing and cutting into an aircraft wing.
A preliminary report in January blamed a 40mm fatigue crack, but it was not known whether it was a design or manufacturing problem.
The Australian agency is being assisted by an inspector from the Transport Accident Investigation Commission, Christchurch-based Ian McClelland, who said yesterday that the final report was likely in about six weeks.
But Air NZ and its Air Nelson subsidiary are conducting their own probes under Civil Aviation Authority oversight into two more scares on domestic flights in recent weeks.
On June 10, an Air Nelson Saab 340 flight from New Plymouth made an emergency landing in Auckland after smoke filled the cabin and the pilot shut one of its two engines.
Just over a week later, on June 18, passengers on an Air New Zealand Boeing 737 flight from Auckland to Wellington were terrified when oxygen masks dropped after a suspected faulty pressure-sensor triggered emergency procedures.
An airline spokesman said yesterday that it had sent a preliminary report to the aviation authority on its investigation into that incident, but was waiting for information from engine repairers to supplement information already gathered on the Saab failure.
One major inquiry was completed this week, when the Transport Accident Investigation Commission confirmed the loss of a 2m wing flap from an Air New Zealand Boeing 747 on August 30 was caused by a stress fracture unlikely to be detected by routine maintenance.
Investigators found that inspection procedures called for by aircraft-maker Boeing were insufficient to ensure any pre-existing cracks would be detected, even though they also noted three earlier fractures of identical parts in planes operated by other airlines.
But the commission said Boeing had since completed a design change to improve resistance to corrosion.
The wing-flap drama, and the engine blowout above Brisbane, were among five incidents which prompted Air New Zealand to commission a "peer review" by Boeing of its safety and maintenance systems.
The airline said in May that the reviewers found human error by its engineers to blame for only one of the five, the loss of a 10kg wing panel which fell from a Boeing 747 into a Manukau carpark on August 24 - less than a week before the flap failure. This was because the aircraft took off with just four screws holding the panel instead of a required 125.
Air NZ said the other four incidents, including the Brisbane engine failure still under investigation, resulted from breakages inside "cycle check times".
Verdict on engine blowout nearing
AdvertisementAdvertise with NZME.