Helicopters Magazine

Products
Longline Vs. Shortline

The longer line provides ground personnel more ‘leverage’ pushing on the load to line up the mounting pins.


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.

Advertisment

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.


Print this page

Related



Leave a Reply

Your email address will not be published. Required fields are marked *

*