UK study says effect of offshore platform on flying environment must be accounted for
Helideck integration in the design of offshore platforms can be crucial to the safety of aircraft, according to a study commissioned by the UK Civil Aviation Authority Safety Regulation Group (SRG).
An earlier study by the SRG had discovered a "lack of any guidance on good offshore helideck design practice", but the new report lays down the considerations for designing a helideck into a number of different types of platform, taking into account the effect of the complete installation design on the flying environment.
Entitled Helideck design considerations - environmental effects, and produced by BMT Fluid Mechanics, the study enumerates the aerodynamic hazards created by the relative position of the helideck to the platform superstructure, masts, exhaust vents or stacks, and flares. If the helipad happens to be roughly downwind of any of these, the risks of complex air turbulence patterns are high, but design can still mitigate the problems, the study suggests.
According to the report, the general rule is that a helideck mounted high relative to the main structures will be less affected by downwind turbulence, particularly if it is set up on a frame with an air space beneath it, allowing the airflow over the deck to be laminar rather than turbulent.
Upwind derricks disturb the airflow less if they are "porous" rather than "clad" structures, and turbine exhaust masts or flares should deliver their rising hot gas plume above all the potential helicopter approach paths.
If the platform is floating, designers should consider positioning the helideck so that it is least affected by roll, pitch, yaw and heave - for example near the stern of a ship rather than close to its bow - while still taking into account the airflow factors and providing good visual cues all the way to touchdown.
The report presents examples of good and bad design practice. Taking account of all the variables including wind direction can demand design compromises for the platform, its structures and the helideck location.
DAVID LEARMOUNT / LONDON
Source: Flight International
