The crash of a Sea King helicopter that slammed into the deck of HMCS Iroquois last year was caused by two turns of a screw, says a military report obtained by the Canadian Press.

Maj. Paul Dittman, the air force's lead investigator of the crash, said an adjustment to the inlet air vein screw by two full turns is what likely caused the compressor to stall.

The report, which was completed on June 30, states that air force mechanics made an adjustment error in a system that controls how air flows to one of the helicopter's two engines.

Sea King helicopter shown sideways on the deck of HMCS Iroquois, last year.
Sea King helicopter shown sideways on the deck of HMCS Iroquois, last year.

Findings show that on Feb. 27, 2003, as the helicopter lifted off the deck of the warship, the pilot gave the aircraft too much power. Seconds later, the pilot rapidly decelerated.

At this point, the helicopter's air vein inlet systems would normally kick in to compensate for the sudden change. But the minor tuning error was enough to cause an engine to stall and the aircraft to plunge onto the destroyer's deck.

"As the pilot decelerated and decreased the amount of fuel going into the engine, there was too much air flowing still, therefore the fuel-air mixture is poor enough to cause a stall," a source told CP.

Since the accident, procedures have been changed to ensure the same error with the engine tuning won't be repeated, said Dittman

The accident, which slightly injured two people, forced the warship to postpone its mission to the Persian Gulf.