.
Purpose made pad eye or ‘floating’ ring fittings welded to the deck.
Ideally the net should be capable of being positioned correctly (centrally over the landing circle) and evenly tensioned from all sides.
Depending on the shape and size of the helideck, this may mean permanently securing the landing net on one or two sides and tensioning from the remaining sides.
(Photo courtesy of John Burt Associates Limited) (Photo courtesy of John Burt Associates Limited)
(Photo courtesy of John Burt Associates Limited) (Photo courtesy of John Burt Associates Limited)
It is best to avoid installing a helideck net fixing system:
.
That has fixings on the helideck surface beyond the perimeter. These will be additional ‘trip hazards’. However, such an arrangement may be unavoidable on very large helidecks
.
That does not allow adjustable strops to be used to tension the net routinely
.
That relies on a rope tensioning arrangement. Routine tensioning will be very difficult and time consuming.
9.7.6 Helideck Landing Net Removal
The removal of helideck nets is not permitted on mobile installations or vessels save in exceptional circumstances and with BHAB Helidecks acceptance. To achieve this acceptance, an assessment may be required in order to demonstrate that the risks are acceptable.
In the case of skidded helicopters, the fitting of nets is subject to the specified requirements of the helicopter operator. Nets may constitute a particularly serious hazard to skidded helicopters.
There are, however, operational disadvantages with installing helideck nets, such as passenger trip hazards, obscuring deck markings, and restricting the clearance of spilt fuel.
These operational disadvantages have prompted owners of fixed installations to move towards providing and maintaining enhanced friction surfaces in lieu of helideck nets. The enhanced friction surfaces may include tiling systems that to some extent still provide visual cues for landing due to the ‘grouting lines’ being visible from the air.
From a flying perspective, there may be a case for retaining nets on some offshore helidecks.
The appearance of the three-dimensional mesh from some distance above, when landing, provides flight crews with a good reference (visual cue) of the height above the helideck and the closure rate, particularly at night when many other visual clues are absent. Net removal will eliminate this valuable visual clue.
Approval to remove the helideck net will only be given if the friction surface achieves average surface friction values (see CAP 437) using an approved testing device. This approval for net removal is generally limited to fixed installations.
After approval has been given to remove a landing net, the surface friction will be subject to routine re-testing, the periodicity will depend on the results achieved from previous friction tests (See CAP 437 – Friction Requirements for Landing Area Net Removal, CAA Paper 98002 [Ref: 42]).
中国航空网 www.aero.cn
航空翻译 www.aviation.cn
本文链接地址：离岸直升机起落甲板设计指南 OFFSHORE HELIDECK DESIGN GUIDELINES 1(56)
