离岸直升机起落甲板设计指南 OFFSHORE HELIDECK DESIGN GUIDELINES 1(50)

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9.3.2  Steel
Older installation and vessel helideck landing surfaces tend to be of traditional steel plated construction.  This material is relatively cheap and simple to fabricate but the final assembly is relatively heavy compared with an aluminium or passive steel deck.
Disadvantages of a steel panelled helideck in service are:
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The surface requires initial and periodic painting and may require the incorporation and maintenance of non-slip aggregate to provide a suitable friction surface, if this is specified

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The helideck surface may be subject to water and fuel puddling due to minor in-service deformation of the panels.

9.3.3  Aluminium
Since the 1980s, aluminium helideck surfaces have tended to be the norm for helidecks in the North Sea.  This is because they have the advantage of being lighter in weight than a comparable steel surface.
Normally, the aluminium surface is constructed from extruded ‘planks’ which are locked into position to form a pancake assembly.
The ‘planks’ have built in friction surfaces formed by ribs on the extrusion surface. Often, however, good friction values are only achieved in one direction (e.g. across the ribs). The designer should therefore specify a requirement for the extrusions to be ‘milled’ across the ribs to obtain adequate friction properties in all directions.
9.3.4  Passive Helideck
A passive type helideck can be fabricated from aluminium or steel.  The surface is perforated to allow liquid to pass through it into drainage trays beneath. There are two types of ‘passive’ system. These are: 
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With the void below the perforated deck surface partially filled with a metal ‘matting’ material.  This prevents any unburned fuel from igniting.  See Figure 9.1

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With a foam spray system installed in channels beneath the open mesh surface to extinguish any burning fuel.

The advantages of specifying a helideck design that offers passive fire safety features should be considered.  Such helidecks can:

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Potentially reduce personnel, helicopter and installation exposure to a major helicopter fire, in the event of an incident

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Provide a highly effective ‘built-in’ non-slip surface and eliminate the need for a helideck net (fixed platforms only)

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Significantly enhance the minimum fire safety provisions provided on normally unattended installations

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Reduce the slipping hazard effects of potential guano accumulations.

Potential disadvantages of perforated surface helidecks can be:

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Loss of performance in the hover in ground effect (HIGE).  This tends to be more noticeable in some helicopters with small hover / thrust margins and this will result in a payload penalty

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