FRST 557
Aerial Harvesting: Helilogging
Lesson Overview:
Helicopter Logging (Helilogging) was first introduced into British Columbia as an alternative yarding method for areas that were physically, environmentally, or economically inaccessible to conventional methods. This accessibility was, for many years, measured in terms of development costs for roads.
As resource objectives have become more complex, conventional harvesting methods have sometimes been physically and/or economically inadaptable for meeting objectives or prescriptions. Helicopters have often served to maintain a harvest in these circumstances.
Lesson References:
MacDonald, A.J. 1999. Harvesting Systems and Equipment in British Columbia. Forest Engineering Research Institute of Canada Handbook No. HB-12. BC Ministry of Forests. Victoria. • Available through Crown Publications http://www.crownpub.bc.ca • Download from: http://www.for.gov.bc.ca/hfd/pubs/docs/sil/sil468.htm
Worker's Compensation Board of British Columbia, Helicopter Operations in the Forest Industry, (Reference No: BK 13) http://www.worksafebc.com/publications/health_and_safety/by_topic/assets/pdf/helicopter_ops.pdf
Credits
This lesson has been enhanced with photographs, illustrations, and information from: Michelle Dunham, Forest Engineering Research Institute of Canada (FERIC) Philip Jarman, (standing stem information)
FRST 557 - Aerial Harvesting
Lesson Objective:
Upon completion of this lesson you will be able to: 1. Describe the advantages and disadvantages of helicopter logging 2. Recognize different types of helicopters & configurations currently used in B.C. 3. Plan for helicopter logging, including patch cutting, selection cutting, and standing stem cutting.
Why Helilog?
The use of helicopters has possibly been the most physically dramatic and cost significant change that has ever happened in timber harvesting methods. The system carries positive and negative factors at the extreme ends of operational decision making. It also presents a number of ethical challenges to the planning forester which are not discussed here.
Advantages
1. Expanded operable forest land base 2. Reduced road building 3. Reduced or eliminated yarding related disturbance 4. Flexibility in block design to address non-timber objectives 5. Improved log quality recovery 6. Quick mobilization to respond to short term opportunities such as damaged timber or market opportunities
Disadvantages
1. Cost Typical tree to truck cost ranges: Ground-based systems: $12/m3 to $20/m3 Cable systems: $30/m3 to $45/m3 Heli-logging systems: $50 / m3 to $80 / m3 2. Ethical Issues Helilogging planning presents many contradictions within ethical standards for a professional forester
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FRST 557 - Aerial Harvesting
Types of Helicopters
Helicopters used in logging are divided into three types based on their lifting capacity. The actual amount of payload lift will vary depending on the amount of fuel carried and air temperature (which affects air density).
Light-lift (rated payload < 10,000 pounds)
Helicopter Rated Payload (lbs.) Bell 204B 4 000 Bell 205A 5 000 Bell 212 5 000 Bell 214B 8 000 SA-315 Lama 2 500 K-1200 K-Max 6 000 Sikorsky S-58T 5 000
K–1200 K-Max Rated Payload of 6,000 pounds
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FRST 557 - Aerial Harvesting
Bell 214B Rated Payload of 8,000 pounds
Medium-lift (rated payload 10,000 pounds to 15,000 pounds)
Helicopter Rated Payload (lbs.)
Boeing V-107II 10 500
Kamov KA-32T 11 000
Sikorsky S-61 10 000 Sikorsky S-61 11 000 “Shortsky”
Sikorsky S-61N Rated Payload of 10,000 pounds
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FRST 557 - Aerial Harvesting
Kamov KA-32T Rated Payload of 11,000 pounds
The counter-rotating blades of the Kamov and the smaller K-Max allow for the elimination of the tail rotor.
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FRST 557 - Aerial Harvesting
Heavy-lift (rated payload >15,000 pounds)
Helicopter Rated Payload (lbs.)
Boeing CH-234 28 000
Sikorsky S-64E 20 000
Sikorsky S-64F 25 000
Sikorsky S-64E Rated payload of 20,000 pounds
Sikorsky S-64F Rated payload of 25,000 pounds
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Boeing CH-234 Chinook Rated Payload of 28,000 pounds
Support Helicopters
Support helicopters are used to “ferry” crews and supplies around the work area.
Bell 206B Jet Ranger
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FRST 557 - Aerial Harvesting
Hughes 369D
Configurations
Like cable yarding, helilogging can use either a cable “choker” or a grapple to attach the system to the log. In either case, a long cable of up to 200 feet (61 m) is attached to the helicopter. This long cable keeps the machine clear of standing trees and obstacles in steep terrain, but it also helps to reduce the impact of the tremendous propeller wash (wind) at ground level. In addition to the lifting cable, there is a hydraulic line which controls the grapple (to open and close) or the hook (which releases the chokers).
Hook and Chokers
Hook Configuration
Long--lineline
Double Hook
Chokers
A ground crew will preset several chokers. When the helicopter lowers the long line with the hook, the crew attaches the chokers to the hook. The helicopter lifts the logs and flies to the drop zone where the hook is activated to release the chokers. The chokers are unhooked after the helicopter has returned to the pick- up area. Chokers are bundled in the drop zone and retuned to the block (usually) with the service helicopter.
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Grapple
Grapple Configuration
Conventional Grapple
Standing Stem Grapple
Using a grapple eliminates the need for a large ground crew and thus reduces worker exposure to safety hazards. The grapple significantly improves cycle time for the helicopter.
Grapples have a disadvantage of limited turn volumes (as compared to chokers) and a limited ability to identify non-merchantable logs. Turn volumes can be optimized through machine bunching (a buncher is flown in) or by pre-setting several chokers in a series to a “pick log” (see photo blow).
A variation to grapple helilogging is standing stem logging, which will be discussed later.
Grapple/Choker Configuration
Grapple
Pick--loglog
Two--belled chokers
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FRST 557 - Aerial Harvesting
Planning and Layout
Selecting the Yarding Helicopter
Because of the very high cost of this system, helicopter logging needs to be an exercise of looking at costs by the minute and considering costs and benefits of every option and variable.
Depending on the species, the size of trees, and potential log grades (which are subject to correct optimum log lengths), the optimum helicopter can be chosen based on its payload capacity. Where bigger and heavier logs are the desired product, a bigger helicopter is desirable.
The target turn (all of the logs lifted at once) weight must align with the rated lift capacity of A common volume to weight conversion used the helicopter. Obviously, when considering the 3 cost, a maximum turn weight is a target. is 1 m = 2000 pounds. Normally however, turns only average 80% to 85% of the rated capacity on choker blocks. This Adjustments are made happens because of the variability in the sizes and based on species, quality weights of logs available to make up a turn. of limbing and topping, Ground crews must select the turn in advance of and time since falling. the helicopter arriving for the pick-up and have all chokers set and ready to attach to the hook when it is dropped. If a turn is too heavy, the entire load is dropped (or “aborted”) and the helicopter will fly to another crew while the overweight turn is reconfigured.
Another problem is “breaking out” a turn. Often logs will be interlocked with other logs (not in the turn) and branches and tops. Although these extras will shake free and be left behind once the turn is lifted, they are part of the initial load.
The challenge of maximizing turns is greater for the grapple systems. Good success has been achieved by lifting bunchers into heli-blocks to assemble optimum weight turns for larger “bunching grapples”.
Topography, length of haul, and slope of haul can also influence the choice of machine.
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FRST 557 - Aerial Harvesting
Landing Location
As with any yarding system, distances will have a direct correlation with cost.
Helilogging blocks most typically have a landing within 1 mile (1.6 km), but this may vary upward if timber quality and other factors are favourable.
Landing Location Factors requiring consideration: •• flightflight distancedistance •• flightflight pathpath slopeslope •• predominant wind directions Cutblock centre •• potential obstructions
Chord distance
Landing Landing FlightFlight pathpath
The actual flight path is rarely a straight line from the pick-up to the landing. Some influences include wind speed and direction, a desired flight slope, location of crews and equipment, and layout of the landing.
Flight path slope is a very important consideration in planning a helicopter operation. Depending on the machine, a favorable glide of 30% to 35% is generally preferred. A greater slope requires extra power to “put on the brakes” while a lesser slope requires extra lifting power.
Flight Path Slope: log hook-up position
drop zone
Yarding productivity can be adversely affected by: • steep flight path slopes (>35%) • flat or nearly flat flight path slopes
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The following table, based on actual observations, gives some idea of the distribution of time for a typical helilogging operation. Note the significance of the fixed times (hook, unhook, and breakout). Any improvement to these functions will have a significant improvement to production.
Examples of Turn Time Break-down Fly loaded Hook/ and Breakout/ Fly empty Unhook Helicopter Prescription (%) (%)
Bell 214B variable retention 41 59
Bell 214B variable retention 49 51
Boeing CH-234 clearcut 45 55
K-1200 K-Max clearcut 47 53
Sikorsky S-64E vr & cc 42 58 Note: Flight distance, flight path slope and rigging configuration vary for each study.
Source: Forest Engineering Research Institute of Canada
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Landing Size
Because of the high productivity of helilogging, landing facilities must be large enough, and efficient enough to allow for NO impediments to the helicopter. There can be no delays in landing the logs, but at the same time chokers must be recovered (if used) and logs are processed and loaded. Sometimes, two or more small landings may be used to achieve this. Water drops are preferred wherever available.
Logs may also be inventoried in piles in a landing or at roadside if loading is to be delayed. The grapple is more suited to this than chokers.
Logs piled at roadside for later loading. When selecting a landing, consider: Type of helicopter Type of equipment to be used in the landing Size and functions of landing crew (scaling and bucking on site?) Log lengths Allowance for waste wood storage and handling Total volume serviced by the landing and expected productivities Log inventories
A service landing is also required. This will serve as an operation base for the logging helicopter and for the support helicopter.
Selecting this site must consider: Types of helicopters Fuel storage Facilities for repairs and maintenance Weather protection Distance to the operation Crew facilities
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Block Design
Because helilogging blocks are not restricted to road access, skid trails, or cable yarding conditions there is great flexibility in design. Almost any size or shape is an option, therefore heli block layout can adapt to many unique situations.
If helilogging is planned to use ground crews and chokers, the block must allow for several ground crews working at the same time. Up to five crews may be needed to keep up with the helicopter’s production. As an alternative to a singe block, several small blocks may be worked simultaneously.
Cutblock Size and Shape
Ground crews can safely work several locations simultaneously.
Helicopter logging is not the solution to every access or topographic challenge. Fallers must still be able to access, fall and buck timber to appropriate specifications
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Prescription Selection
Helicopter logging is adaptable to any silvicultural system. As with any yarding system though, productivities tend to decline as the system gets more complex. The following table illustrates this.
Prescription Selection
Patch-cut Single tree Clearcut (25% (25% removal) removal) Detail Timing Fly empty &loaded (min) 1.18 1.18 1.18 Position &hook-up (min) 0.78 0.79 0.94 Break-out (min) 0.40 0.46 0.53 Total turn time (min) 2.36 2.43 2.65
Yarding Productivity Turns/ flight-h (no.) 25.4 24.7 22.6 Payload/ flight-h (lbs.) 381 355 370 370 339 623
Source: Forest Engineering Research Institute of Canada
Weather
Helicopter logging is adversely affected by weather more than any other yarding system. Fog, heavy wind, and snow can fully stop an operation or limit productivity.
When scheduling helilogging, avoid seasons where weather patterns would cause significant and expensive down time.
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FRST 557 - Aerial Harvesting
Standing Stem Selection
Standing stem selection is an adaptation of helilogging to single stem selection. The system was developed in 1998 by helicopter pilot/entrepreneur Philip Jarman along with MacMillan Bloedel Limited and FERIC. Jarman had already patented the helicopter grapple and saw potential to modify it for this application.
Standing stem harvesting requires pre-selection of trees.
Trees are climbed and limbed.
The top is removed, and the tree is cut at the base with two horizontal cuts leaving a prescribed hinge of holding wood. The cuts are wedged during cutting to keep the tree from swaying.
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The cut tree may be left standing for some time to allow it to dry and reduce its weight. Any number of trees can be prepared in an area. The cut trees are remarkably stable because all branches and the top have been removed.
Harvesting is completed with a helicopter equipped with a horizontal oriented grapple.
The grapple is lowered and attached to the tree near the top and then the helicopter forces the top to rock until the tree snaps off at the pre-cut stump.
The full-length log is then lifted clear…
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…and flown to the landing.
Although standing stem harvesting is obviously an expensive system, it has found a niche in harvesting systems. Because the tree is not felled, there is no shatter damage to the wood. In very valuable sawlog timber, customers have been willing to pay enough of a premium to cover the incremental costs.
A Final Word
In the context of physical layout, helicopter logging is a relatively simple harvesting system. It is however, a very complex system in the context of financial and logistic planning.
Helicopter logging can be used wisely, but it is sometimes misused as well. It has been a topic or factor of many ethical challenges such as worker displacement, revenue misrepresentation, high grading, and inappropriate regeneration planning. It has been carefully planned and integrated with conventional systems. It has also been used as an emergency solution to retrieve felled and bucked timber that is out of reach of a yarder due to poor engineering.
It is a system that often leaves a small footprint on the ground but a big impact in the records.
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