Over the years, offshore wind turbines have increased significantly in size and power output. Challenging remote areas and increasingly heavy components create great challenges for the [...]
Many flare tips are still replaced by helicopters. A Norwegian contractor has gained a significant market share with this service. The lifting helicopters are sometimes called ‘aerial cranes’ or ‘sky cranes’. A typical crew for a helicopter flare-tip replacement operation consists of one or two pilots and two mechanics acting as load masters / signallers. The aircraft load capacities range from 500 kg (Bell 206 B) to 4000 kg (Super Puma AS332). The pilots use the ‘long-line’ flying technique, which allows the pilot to fly while looking down through a Plexiglas viewing bubble.
Disadvantages of helicopter flare-tip replacement
The industry is reluctant to choose helicopter flare-tip replacement due to its many disadvantages, including:
- The mechanics need to position themselves on the flare-tip access platform to connect the load and guide the helicopter pilot. The platform is small, and there are no rapid-escape possibilities if the load starts to swing.
- From the cockpit, the pilot usually cannot see where the hook is — even with plexiglass side-bubbles or removable doors. The pilot must rely on the signaller’s communication to manoeuvre into position.
- Hovering with a load is a difficult, fatiguing and potentially dangerous activity that requires a high level of pilot concentration and should therefore be limited in time.
- In dangerous situations, the pilot may choose to release the load. For this purpose, the aircrew have a remote electric hook release and access to a manual release at the aircraft end of the load line. The load is irretrievably lost in the sea.
- Rotor downwash causes strong gusts, turning dust, dirt and loose objects into airborne projectiles.
- The helicopter needs a take-off and landing area. If the work site is far offshore, this will probably be the platform’s helideck. For the duration of this risky offshore operation the helideck cannot be used for other helicopter operations.
- Helicopter lifting operations are very expensive.
Advantages of mechanical flare-tip replacement
Conbit’s mechanical flare-tip replacement method is not only more reliable but also much safer than using a helicopter. Although the required shutdown time may be one or sometimes two days longer, the downtime is known in advance and certain. Bringing in mechanical handling tools is much easier than deploying a suitable helicopter. Also, risks are better controlled because the mechanical flare-tip replacement method consists of a series of small, easily manageable steps. As many people in the industry prefer mechanical handling methods, it is easy to convince management to choose this better and safer solution. The required team is smaller than in the case of helicopter flare-tip replacement. For these reasons, many clients prefer to use the mechanical flare-tip replacement method.
Some examples of successful offshore flare tip replacement projects by Conbit: