A UK Civil Aviation Authority flight operations department communication (FODCOM) says helicopter pilots should receive more guidance on helideck landings in foul weather. The advice follows an Air Accident Investigation Branch (AAIB) report on a 10 November 2001 accident, in which a Eurocopter AS332L Super Puma rolled over in crosswind when the ship it landed on yawed unexpectedly.

The CHC Scotia helicopter (G-BKZE) was being refuelled on the oil drilling ship's helideck with rotors running, but when it rolled, the co-pilot, who was on the deck to help the ship's crew while the captain stayed at the controls, was badly injured by flying debris.

The helicopter landed on the West Navion, and the crew kept the engines running. It is standard practice for helicopters waiting on ships in high wind as the turning rotors provide a degree of stability. The wind was 35kt (65km/h), gusting 45kt, but the ship's dynamic positioning system had reverted to manual heading control without the crew of the ship or the helicopter noticing, and its heading began to drift right, exposing the helicopter to increasing crosswind from the left. About 7min after the heading drift began, the aircraft rolled to its right, primarily under aerodynamic forces, the report says.

FODCOM says that on landing the helicopter had adopted a 2.5º roll attitude to the right relative to the helideck surface "due to the effect of the landing gear geometry and the normal procedure of landing with the parking brake applied". FODCOM observes that it is now recommended that the helicopter is levelled as near as possible relative to the helideck, and that "releasing and reapplying the handbrake to let the helicopter settle may help to achieve this".

The AAIB recommends that operators conducting flights to and from offshore helidecks, both fixed and moving, should produce guidance for crews covering "at least the following topics" when operating in adverse weather:

 * attitude levelling on deck;

 * crew remaining at controls;

*  procedures for passenger changeover;

*  refuelling.


Source: Flight International