Longline Vs. Shortline

The importance is knowing when to switch
Ken Armstrong
July 13, 2007
By Ken Armstrong
Sure, heavy, multi engine helicopters engaged in heli-logging will almost always use a long line as many factors dictate the need for their pilots to work high above their loads. These considerations include minimizing rotor wash on personnel below while keeping clear of flying debris such as sawdust, fire ash and objects blown up in the rotor wash. Also, helicopters manoeuvring over steep terrain and tall trees require long lines to avoid chopping up firewood with the rotor blades. Where logs are being dropped into the corrosive ‘salt chuck’ the long line keeps the helicopter out of the splash zone and provides an additional safety margin above obstacles in the event a pilot misjudges his height above glassy water.

For the precision placement of external loads, such as the lineup of a heli-portable drill on its frame, the longer line provides ground personnel more ‘leverage’ pushing on the load to line up the mounting pins. Having said that, a really good pilot can use a short line and – with precision flying – line up the pins. I’ve seen it many times. Other tasks that suggest employing a long line are placement of air-conditioning units on rooftops, and tall loads such as power poles or business signs. Any payload that must be ‘fished out’ or placed between tall trees or surrounded by immovable obstacles also demands a long line. A side benefit of hovering above the trees is the possibility of beneficial winds aiding the rotor in lifting the loads.

One major decision maker for line-length selection is the effect the rotor wash will have on personnel and equipment on the ground. As helicopters work closer to buildings and high-density populations, this requires more thoughtfulness. Of course, there are exceptions dictated by the ambient circumstances. For instance, when communications gear and towers were placed on the CN Tower in Toronto, the S- 64 Skycrane crew opted for a short sling for precision placement.

‘Sling shotting’ requires a long line. While the procedure is arguably risky, some pilots use long lines to lift loads that are too heavy for the helicopter to lift vertically. While it would be unwise to promote this technique, full coverage of the topic dictates providing details. Typically, the pilot moves downwind of the sling load and, facing into the wind, accelerates in a climb hoping to reach translational lift as he comes overhead the payload – pulling it skyward with the extra lift. Not for the timid, not recommended for obvious safety reasons and not effective with a short line.

Another high-risk technique for lifting loads that are too heavy due to hot/high considerations (not over gross – that would be illegal) is the spinning takeoff. In this technique, the pilot applies full power to get the load light and then removes the anti-torque, (tail rotor) input allowing the torque to spin the helicopter around its vertical axis. Unloading the tail rotor provides approximately 10- 16% more torque for vertical lifting. Once the load is 20-30 feet off the ground, the pilot tilts the rotor disk to accelerate through translational lift and then applies anti-torque pedal input to return to balanced flight. However, this is another technique that is frowned on for safety reasons and it can be hard on equipment if not done smoothly. This method can be accomplished with any length of line but is likely safer with a long line as the helicopter will be higher and therefore clear of obstacles as it slowly spins. Sometimes the length-of-line decision may be swayed by customer input. A manager who is familiar with the benefits of long lining for his personnel may request (or demand) the use of a long line. These clients may motivate compliant pilots to leave the short line in the equipment box. The best way to handle this situation might be to educate the boss on the safety and efficiency implications that sometimes dictate shortline use.
More in this category: « No Rotor Unturned  |  Power Vision »

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