An encounter with a waterspout between storms over the North Sea seriously endangered a Bristow Helicopters Eurocopter AS322L Super Puma with a crew of two and 18 passengers, according to the UK Air Accident Investigation Branch (AAIB).

The 28 February incident, on a flight from the Dunlin A platform to Scatsta in the Shetland Islands north of the Scottish mainland, involved severe turbulence and resulted in damage to the helicopter's tailrotor and tail pylon.

The meteorological phenomenon was not visible to the crew, who were tracking to avoid storm cells, but just before the encounter, the captain saw a disturbance on the water surface that he associated with a developing waterspout. The aircraft then pitched, climbed and rolled dramatically, tripping out the auto-pilot, and the captain managed to recover control. Once out of the area of severe windshear, the crew recovered the flight.

An examination found that the rear rotor blade tips had cut into the tail pylon, causing damage. The AAIB says the rotor, incorporating A9 blades, survived the impact, whereas the earlier A1 standard blades may not have.

Source: Flight International