frst 557 aerial harvesting:...

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)

http://www.crownpub.bc.ca/

http://www.for.gov.bc.ca/hfd/pubs/docs/sil/sil468.htm

http://www.worksafebc.com/publications/health_and_safety/by_topic/assets/pdf/helicopter_ops.pdf

FRST 557 - Aerial Harvesting

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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


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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


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Bell 214B


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”


10 500

11 000

10 000

11 000

Sikorsky S-61N



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Kamov KA-32T


The counter-rotating blades of the Kamov and the smaller K-Max allow for the

elimination of the tail rotor.


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Heavy-lift (rated payload >15,000 pounds)


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


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Boeing CH-234 Chinook


Support Helicopters

Support helicopters are used to “ferry” crews and supplies around the work area.

Bell 206B Jet Ranger


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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.


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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


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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.


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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


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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

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


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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 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


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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

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.


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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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