HELIDECK - OBSTACLE LIMITATION SURFACES
HELIDECK - OBSTACLE LIMITATION SURFACES
A heliport located on a fixed or floating offshore facility such as an exploration and/or production unit used for the exploitation of oil or gas.
Shipboard heliport. A heliport located on a ship that may be purpose or non-purpose-built. A purpose-built shipboard heliport is one designed specifically for helicopter operations. A nonpurpose-built shipboard heliport is one that utilizes an area of the ship that is capable of supporting a helicopter but not designed specifically for that task.
Winching area. An area provided for the transfer by helicopter of personnel or stores to or from a ship. For helidecks that have a 1 D or larger FATO it is presumed that the FATO and the TLOF will always occupy the same space and have the same load bearing characteristics so as to be coincidental. For helidecks that are less than 1 D, the reduction in size is only applied to the TLOF which is a load bearing area. In this case, the FATO remains at 1 D but the portion extending beyond the TLOF perimeter need not be load bearing for helicopters. The TLOF and the FATO may be assumed to be collocated.
HELIDECK
A helideck shall be provided with one FATO and one coincident or collocated TLOF.
A FATO may be any shape but shall be of sufficient size to contain an area within which can be accommodated a circle of diameter of not less than 1 D of the largest helicopter the helideck is intended to serve.
A TLOF may be any shape but shall be of sufficient size to contain:
a) for helicopters with an MTOM of more than 3 175 kg, an area within which can be accommodated a circle of diameter not less than 1 D of the largest helicopter the helideck is intended to serve; and
b) for helicopters with an MTOM of 3 175 kg or less, an area within which can be accommodated a circle of diameter not less than 0.83 D of the largest helicopter the helideck is intended to serve.
For helicopters with a MTOM of 3175 kg or less, the TLOF should be of sufficient size to contain an area within which can be accommodated a circle of diameter of not less than 1 D of the largest helicopter the helideck is intended to serve.
A helideck shall be arranged to ensure that a sufficient and unobstructed air-gap is provided which encompasses the full dimensions of the FATO.
The TLOF shall be dynamic load-bearing. The TLOF shall provide ground effect. No fixed object shall be permitted around the edge of the TLOF except for frangible objects, which, because of their function, must be located thereon.
For any TLOF 1D or greater and any TLOF designed for use by helicopters having a D-value of greater than 16.0 m, objects installed in the obstacle- free sector whose function requires them to be located on the edge of the TLOF shall not exceed a height of 25 cm.
For any TLOF 1D or greater and any TLOF designed for use by helicopters having a D-value of greater than 16.0 m, objects installed in the obstacle-free sector whose function requires them to be located on the edge of the TLOF should be as low as possible and in any case not exceed a height of 15 cm.
For any TLOF designed for use by helicopters having a D-value of 16.0 m or less, and any TLOF having dimensions of less than 1D, objects installed in the obstacle-free sector whose function requires them to be located on the edge of the TLOF, shall not exceed a height of 5 cm.
Lighting that is mounted at a height of less than 25 cm is typically assessed for adequacy of visual cues before and after installation. Objects whose function requires them to be located within the TLOF (such as lighting or nets) shall not exceed a height of 2.5 cm.
Such objects shall only be present if they do not represent a hazard to helicopters. Examples of potential hazards include nets or raised fittings on the deck that might induce dynamic rollover for helicopters equipped with skids. Safety devices such as safety nets or safety shelves shall be located around the edge of a helideck but shall not exceed the height of the TLOF.
The surface of the TLOF shall be skid-resistant to both helicopters and persons and be sloped to prevent pooling of water.
Obstacle-free Sector/Surface - Helidecks
A complex surface originating at and extending from, a reference point on the edge of the FATO of a helideck. In the case of a TLOF of less than 1 D, the reference point shall be located not less than 0.5 D from the centre of the TLOF.
An obstacle-free sector/surface shall subtend an arc of specified angle. A helideck obstacle-free sector shall comprise of two components, one above and one below helideck level:
a) Above helideck level. The surface shall be a horizontal plane level with the elevation of the helideck surface that subtends an arc of at least 210 degrees with the apex located on the periphery of the D circle extending outwards to a distance that will allow for an unobstructed departure path appropriate to the helicopter the helideck is intended to serve.
b) Below helideck level. Within the (minimum) 210-degree arc, the surface shall additionally extend downward from the edge of the FATO below the elevation of the helideck to water level for an arc of not less than 180 degrees that passes through the centre of the FATO and outwards to a distance that will allow for safe clearance from the obstacles below the helideck in the event of an engine failure for the type of helicopter the helideck is intended to serve.
For both the above obstacle-free sectors for helicopters operated in performance class 1 or 2, the horizontal extent of these distances from the helideck will be compatible with the one-engine-inoperative capability of the helicopter type to be used
Where obstacles are necessarily located on the structure, a helideck may have a limited obstacle sector (LOS). A complex surface originating at the reference point for the obstacle-free sector and extending over the arc not covered by the obstacle-free sector within which the height of obstacles above the level of the TLOF will be prescribed.
A limited obstacle sector shall not subtend an arc greater than 150 degrees. Its dimensions and location shall be as indicated in Figure 4-8 for a 1 D FATO with coincidental TLOF and Figure 4-9 for a 0.83 D TLOF.
Comments
Post a Comment