Chopper doomed before crew knew.

SUPER Puma flight 85N was doomed almost three minutes before the 16 men on board knew anything about it.

Investigators yesterday revealed the disaster which killed two crew and 14 oil workers in April might have been avoided.

A flake of metal in the main rotor gearbox was spotted by a detection system. But no alarms went off to let the crew know.

The Air Accident Investigations Board have now called for a review of design and operating parts.

Yesterday, it emerged co-pilot Richard Menzies called Aberdeen airport at 12.54pm reporting the Bond-operated helicopter was in working order and on course to land. Seconds later, he or Captain Paul Burnham made a mayday call.

And 11 miles off Peterhead, the aircraft plummeted into the sea.

The report found that the flake of metal was detected in the gearbox mechanism around 12.51pm.

Over the next minute and 43 seconds, three further fragments were detected. But the report stated: "The design of the chip detection system is such that the flight crew would not have been aware of this."

The black box recorder revealed a warning of low oil pressure in the gearbox and a subsequent drop.

The AAIB said the reason remains "as yet unknown".

The investigation continues.

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WRECKAGE: The doomed Puma