Boeing refuses comment on warning letters

By MATHEW DEARNALEY

Aircraft manufacturer Boeing will not say whether it sent service advisory notices to Air New Zealand about wing part failures in recent years on 747 jumbo jets.

The company says it circulated two notices to airlines generally in the late 1990s after problems with inboard wing fore-flaps, but stopped short of confirming yesterday whether Air New Zealand was an intended recipient.

Air New Zealand says Boeing has now advised it of three flap failures, but only since a 2m piece broke off a wing of one of its own jumbos a fortnight ago.

The piece plunged into the Manukau Harbour after causing minor damage to the plane's fuselage and tail.

Airline chief technical officer Bill Jacobson insisted at a press briefing in Auckland on Wednesday that it had received no earlier advisory notices, and a search of its records had drawn a blank.

Issuing initial findings of inquiries into the losses of the flap and of a wing panel from another 747 a week earlier, he said configuration control and maintenance practices for the fore-flap assemblies complied fully with Boeing and Civil Aviation Authority requirements.

The failed flap was one of 10 used on the wings of Boeing 747s to increase lift on takeoff and to allow aircraft to slow down for landings without stalling.

Mr Jacobson said tests of a broken lug meant to secure the flap to a load-bearing structure pointed to corrosion, followed by fatigue cracking, as the probable causes.

Boeing had since advised the airline of three similar failures within five years involving "this specific part" on other jumbos.

The manufacturer's Australian and New Zealand regional communications director, Ken Morton, reiterated from Sydney yesterday that Boeing had sent an advisory service letter in 1998 and then an update the next year after flap incidents.

But when asked to confirm that the letters went to Air New Zealand, he said such matters were confidential to Boeing and its customers.

"I couldn't say that, and even if I could, I wouldn't because it is not our place."

Mr Morton said Boeing was waiting for results of an investigation by this country's Transport Accident Investigation Commission before determining any common cause between the latest loss and previous failures.

He would not say what caused the earlier failures, or predict whether the latest incident may lead to a general parts recall, but noted that the loss of a wing flap did not compromise flight safety despite forcing an aircraft to land at a faster speed.

Air New Zealand says it found "signs of corrosion product staining" on the lug of a second 747 during inspections prompted by the flap loss.

It replaced the lug and says it will do the same to the rest of its fleet of eight 747s by the end of this month.

Mr Jacobson said this was purely a precaution.

Transport commission investigator Ken Mathews said he would seek details from Boeing of its earlier advisory notices, and whether these were applicable to Air New Zealand jumbos.

Meanwhile, he is waiting for Government scientists to complete microscopic tests on a remnant of the broken lug and intends sending the results to Boeing so the company can compare these with findings from the earlier wing-flap failures.