Jet drama over North Shore

A mid-air emergency on a military aircraft over Auckland may delay the return from Afghanistan of more than 100 Defence Force reconstruction staff.

Firefighters and ambulances turned out in strength to the Air Force's Whenuapai base yesterday morning after an engine compressor stalled on a Boeing 757 about 600m above North Shore City.

This caused fuel to build up before back-firing - or "sneezing" in Air Force parlance - sending flames shooting from the rear of one of the Boeing's two Rolls Royce engines.

North Shore residents were alarmed to hear explosions in the sky at 9.10am, about 30 seconds after the aircraft took off with 20 Air Force staff on board, en route to the Middle East via Darwin.

A man walking his dog in Beach Haven told the Herald he heard two sharp bangs, but an Air Force spokesman said there were as many as four in rapid succession.

These were caused by unstable airflow through the compressor, for any of a number of reasons, ranging from atmospheric conditions to a fuel obstruction, during an easing of the aircraft's power settings once it had completed its takeoff.

Six Fire Service vehicles and three St John ambulances rushed to Whenuapai on full alert, to supplement the base's own emergency response teams.

Most of the fire engines, apart from a foam-dispensing tender from central Auckland, were sent from North Shore stations because western suburb appliances were busy at Te Atatu after a truck carrying industrial gases crashed on the Northwestern Motorway at 9.15am.

A hazardous materials appliance also attended the motorway accident after a report of a gas leak.

But supplier BOC said that although a mixture of flammable and non-flammable gases were on the truck, these had all been contained in their storage cylinders.

Motorway traffic was disrupted for about two hours and the truck driver was taken to Waitakere Hospital for medical checks after his eastbound vehicle crashed through two median barriers, ending in a westbound lane.

The 12-year-old Boeing, one of two bought for the Air Force in 2003 to carry troops and VIP parties round the world, flew out to sea to burn off excess fuel, before landing safely back at Whenuapai about 9.45am.

The engine over-heating prompted an intense round of tests to ensure no permanent damage was done.

Wing Commander Tony Davies, head of the Air Force's 40 Squadron of transport aircraft, said high-power engine runs found nothing untoward, indicating that the problem was not as serious as a compression stall, which happened to the other Boeing 757 in Fiji last year.

But these tests would have to be followed by up to 36 hours of a painstaking examination through the bowels of the engine using a fibre-optic camera that the Air Force hoped to borrow from Air New Zealand today.

The aircraft is supposed to collect more than 100 Army, Navy and Air Force staff who have been in Afghanistan for six months on provincial reconstruction projects, and who have been replaced by a sixth New Zealand team.

Wing Commander Davies said the aircraft might be ready for takeoff tomorrow, meaning it could return the team to Auckland on schedule on Tuesday, but it was more likely to be a day late.

The other Boeing 757, which flew Prime Minister Helen Clark to the South Pacific Forum in Samoa last August, was grounded for several days on its homeward journey while a replacement engine was flown to Fiji.

It is now under routine maintenance in the United States, and therefore unavailable to collect the reconstruction team.

Defence Minister Mark Burton said in answer to a parliamentary question from Opposition spokesman John Carter that the cost of the fault in Fiji was estimated at almost $4.9 million.

Wing Commander Davies said compression stalls were not uncommon in such aircraft, but the 757s had otherwise performed "fantastically" since replacing the Air Force's old Boeing 727s.

These were infamous for breaking down on VIP flights, and Mr Carter said yesterday's 757 breakdown continued to highlight a "disgraceful" Government defence record.

But Mr Burton said the Defence Force chief, Air Marshal Bruce Ferguson, had assured him the latest fault appeared unconnected to any lack of technical capability among military staff or the condition of the aircraft.

The aircraft

The Air Force has two Boeing 757-200, which are 12 years old and were bought by the Government in 2003 from the Netherlands, with twin Rolls Royce engines.

Their job is to carry troops and VIP parties round the world at an average cruising speed of 875km/h.

They replaced Boeing 727s, which were too noisy to land at some airports and became notorious for breaking down on international missions.

Both 757s have now suffered engine compression stalls, and one made a emergency landing at Whenuapai early last year after a nose landing gear problem, but the Air Force is pleased with their overall flying performance.