frst 557 aerial harvesting:...
TRANSCRIPT
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
Page 2 of 18
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/m
3
Cable systems: $30/m3 to $45/m
3
Heli-logging systems: $50 / m3 to $80 / m
3
2. Ethical Issues
Helilogging planning presents many contradictions within ethical
standards for a professional forester
FRST 557 - Aerial Harvesting
Page 3 of 18
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
Bell 204B
Bell 205A
Bell 212
Bell 214B
SA-315 Lama
K-1200 K-Max
Sikorsky S-58T
Rated Payload (lbs.)
4 000
5 000
5 000
8 000
2 500
6 000
5 000
K–1200 K-Max
Rated Payload of 6,000 pounds
FRST 557 - Aerial Harvesting
Page 4 of 18
Bell 214B
Rated Payload of 8,000 pounds
Medium-lift (rated payload 10,000 pounds to 15,000 pounds)
Helicopter
Boeing V-107II
Kamov KA-32T
Sikorsky S-61
Sikorsky S-61
“Shortsky”
Rated Payload (lbs.)
10 500
11 000
10 000
11 000
Sikorsky S-61N
Rated Payload of 10,000 pounds
FRST 557 - Aerial Harvesting
Page 5 of 18
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.
FRST 557 - Aerial Harvesting
Page 6 of 18
Heavy-lift (rated payload >15,000 pounds)
Rated Payload (lbs.)
28 000
20 000
25 000
Helicopter
Boeing CH-234
Sikorsky S-64E
Sikorsky S-64F
Sikorsky S-64E
Rated payload of 20,000 pounds
Sikorsky S-64F
Rated payload of 25,000 pounds
FRST 557 - Aerial Harvesting
Page 7 of 18
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
FRST 557 - Aerial Harvesting
Page 8 of 18
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 ConfigurationHook Configuration
Double HookDouble Hook
Long-lineLong-line
ChokersChokers
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.
FRST 557 - Aerial Harvesting
Page 9 of 18
Grapple
Grapple ConfigurationGrapple Configuration
Conventional GrappleConventional Grapple
Standing Stem GrappleStanding 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 Grapple
Pick-logPick-log
Two-belled
chokers
Two-belled
chokers
Grapple/Choker ConfigurationGrapple/Choker Configuration
FRST 557 - Aerial Harvesting
Page 10 of 18
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
the helicopter. Obviously, when considering the
cost, a maximum turn weight is a target.
Normally however, turns only average 80% to
85% of the rated capacity on choker blocks. This
happens because of the variability in the sizes and
weights of logs available to make up a turn.
Ground crews must select the turn in advance of
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.
A common volume to
weight conversion used
is 1 m3 = 2000 pounds.
Adjustments are made
based on species, quality
of limbing and topping,
and time since falling.
FRST 557 - Aerial Harvesting
Page 11 of 18
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.
Chord distance
Chord distance
Flight p
ath
Flight p
ath
Cutblock centreCutblock centre
LandingLanding
Landing LocationLanding Location
Factors requiring consideration:
• flight distance
• flight path slope
• predominant wind directions• potential obstructions
Factors requiring consideration:
• flight distance
• flight path slope
• predominant wind directions• potential obstructions
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-upposition
drop zone
Yarding productivity can be adversely affected by:
• steep flight path slopes (>35%)• flat or nearly flat flight path slopes
FRST 557 - Aerial Harvesting
Page 12 of 18
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
Note: Flight distance, flight path slope and rigging configuration vary for each study.
Hook/
Breakout/
Unhook
(%)
59
51
55
53
58
Fly loaded
and
Fly empty
(%)
41
49
45
47
42
Prescription
variable retention
variable retention
clearcut
clearcut
vr & cc
Helicopter
Bell 214B
Bell 214B
Boeing CH-234
K-1200 K-Max
Sikorsky S-64E
Source: Forest Engineering Research Institute of Canada
FRST 557 - Aerial Harvesting
Page 13 of 18
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
FRST 557 - Aerial Harvesting
Page 14 of 18
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 ShapeCutblock 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
FRST 557 - Aerial Harvesting
Page 15 of 18
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
Detail Timing
Fly empty &loaded (min)
Position &hook-up (min)
Break-out (min)
Total turn time (min)
Yarding Productivity
Turns/ flight-h (no.)
Payload/ flight-h (lbs.)
Clearcut
1.18
0.78
0.40
2.36
25.4
381 355
Patch-cut
(25%
removal)
1.18
0.79
0.46
2.43
24.7
370 370
Single tree
(25%
removal)
1.18
0.94
0.53
2.65
22.6
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.
FRST 557 - Aerial Harvesting
Page 16 of 18
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.
FRST 557 - Aerial Harvesting
Page 17 of 18
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…
FRST 557 - Aerial Harvesting
Page 18 of 18
…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.