Plane caught fire before crash

Electrical fire in a fuel tank: Based on an international alert in 2000 that damaged wiring which could lead to "fire and explosions" had been found in six Metroliner aircraft in New Zealand.

Air accident investigators say the Airworks Metroliner that crashed on Tuesday, killing its two pilots, caught fire and broke up in mid-air.

Other aviation sources have said the fact the landing gear was extended indicated the pilots might have been trying to put out a fire in one of the wheel wells.

"A preliminary look at it suggests the fire has been external to the cargo hold," said Transport Accident Investigation Commission investigator John Goddard.

Although it was certain there had been an in-flight fire, "exactly at what stage of the whole sequence that happened, I don't know at this point", he added.

Commission spokesman Ken Mathews was asked yesterday whether two of the scenarios being looked at were a mid-air fire triggered by faulty wiring in a wing fuel tank, or a fire started by an overheated brake assembly retracted into a wheel well in the wing.

He replied that investigators were looking at all possible causes and it was important not to leap to conclusions.

"With an in-flight break-up - which is evident here - there could be a range of reasons why that has occurred."

A wheel well fire or an electrical fire in a fuel tank were just two possibilities at this stage.

But other aviation sources said the fact that one of the plane's wings fell to earth badly burned with the landing gear lowered was an indication that the pilots had tried to put out a fire in the wheel well.

A similar Metroliner crashed in Canada in 1998 after its pilot took off with a parking brake still partly engaged.

The red hot brake assembly started a fire in the wheel well, which had a rubber fuel line running through it. The wing burned through and fell off, killing the two pilots and nine passengers.

Reports of the accident investigation said that a lack of effective warning systems in the wheel well apparently made it difficult for the pilots to recognise the fire had broken out.

The Airworks Metroliner, carrying courier cargo from Auckland to Blenheim, crashed about 10.15pm on Tuesday, 5km east of Stratford. Both wings, one of them with severe burn marks, came off before the wreckage hit farmland. The plane's wheel wells and fuel tanks are in the wings.

The crash killed Clive Rodger Adamson, 43, of Wellington, and Anthony Brian Arthur Drummond, 41, of Manukau City.

Mr Mathews said a series of airworthiness directives had been passed on to all operators of the aircraft, including ones relevant to overheated brakes on landing gear, protecting fuel lines and hydraulic lines in wheel wells, and replacement of brake master cylinders.

A directive in 2003 called for the inspection and modification of fuel boost pump wiring to correct "chafing that could provide an ignition source inside the fuel tank and consequent fire/explosion".

It stemmed from a warning the Civil Aviation Authority gave its international counterparts in September 2000 that damaged wiring which could lead to "fire and explosions" had been detected in six of 20 Fairchild Metroliner aircraft in New Zealand. The planes, operated by three airlines, had chafed fuel boost pump wiring.

- NZPA

Crash theories

Wheel well fire: Based on a similar Metroliner crashed in Canada in 1998.

Electrical fire in a fuel tank: Based on an international alert in 2000 that damaged wiring which could lead to "fire and explosions" had been found in six Metroliner aircraft in New Zealand.