Blade Removal and Leading Edge Tape Replacement -...

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Blade Removal and Leading Edge Tape Replacement

This document describes the process to remove blades, replace leading edge tape and replace the

blades for Excel 5 and Excel 10 turbines.

The time before LE tape will need to be replaced depends on the severity of the environment. In dry

desert like environments the tape may last several years; versus rainy coastal areas may require tape in a

couple of years. Rural farmland areas, where there can be a lot dust in the air will be somewhere in

between.

For further information or materials purchase and warranty support, contact the Service Department at

Bergey Windpower Co. (email: [email protected] or phone: 405-364-4212). If the system is under

warranty, have the system owner’s name, turbine serial number and commissioning date available.

NOTE: Anytime you are up a tower, it is recommended to perform a system inspection,

information on which can be found in the relevant tower installation manual at:

http://www.bergey.com/Technical

Required equipment for blade removal:

- ¾ inch rope, 30ft longer that two times the tower height (e.g. 120ft tower requires minimum 270ft

rope)

- Pulley for the ¾ inch rope, and means of attaching pulley to tower

- Come-along (or ratchet puller/hoist)

- Eye-and-eye lift sling, 8ft long

- 1 1/8 inch (1.125 inch) socket and torque wrench with capacity to 150ft*lbs

- Large carabiner

- Small bungee or small rope or heavy duty zip tie*

- One person on tower

- One person on ground to lift/lower equipment and blades, blades weigh 50lbs/each

Required equipment for LE tape replacement:

- Stands on which to place blades to provide a stable place to work (see Section B of this document)

- LE tape kit

- Fresh razor blades

- Lacquer thinner

- Gloves to protect skin from lacquer thinner

- A measuring tape

- Two cans of protective enamel spray paint and two cans pimer (one can may be sufficient depending

on the painter). Recommendations:

i. Rust-Oleum: Gloss White (#7792) used with either Self –etching Primer (#249322)

or Filler Primer (#249279)

ii. Alternative option: Hammered Paint & Primer in One (Hammered White #265544)

- Scotch Bright 7447 (an abrasive hand pad)

- If there is any erosion in the fiberglass of the blade, you will also need:

- Dynalite by Dynatron (Or equivalent material; this is what our blade techs prefer. May be

found at autoparts store.)

- Straight sander, ideally with varying grits of sandpaper: 36, 80 and 150.


A. Blade Removal

Definition of terms:

Working end: The end of a rope that is active in knot tying.

Standing end: The end of a rope that is not active in knot tying; the end opposite the working

end.

Standing part: Section of rope between the know an the standing end.

1) Short the turbine as described in the tower installation manual.

2) Feed rope through the pulley, and tie a stopper knot 20ft from the working end.

3) Climb the tower with the pulley and working end of the rope.

4) Secure the pulley to the tower just below the tower adapter plate.

5) Lower working end of the rope through the pulley to the ground crew, so they can trolley up the

following gear:

� Lifting sling, come-along, torque wrench, socket, small bungee.

NOTE: Tie the tip of the working end to the carabiner. Then clip the carabiner around

the lift line. This allows the load to “trolley” up the lift line as the ground crew pulls;

keeping the load from contacting the tower.

6) Remove the nose cone (spinner) and attach it to the tower with the small bungee (or small rope

or heavy duty zip tie*). Position the nose cone on the opposite side of the tower, out of the way.

7) Position the lifting sling over the top of the alternator, and connect both eyes of the sling to the

ratcheting end of the come-along.

8) Connect the hook end of the come-along to a secure spot at least 6 feet down the tower.


9) Position the first blade to be removed such that it is pointing straight down, and tighten the come-

along. This will keep the alternator from rotating after you remove this lower blade.

10) Loop the rope around the blade twice immediately under the root pad, and use two opposing half-

hitches to secure the working end to the standing part (The standing part passes through the

pulley and becomes the lift line). This creates a slip knot. Pull on the standing part and work the

slip knot snugly under the step of the root pad.

NOTE: There needs to be greater than 6 inches of slack in the standing part between the

slip knot and the stopper knot. This will allow enough slack to later move the blade out

and over the ends of the blade studs during removal.


11) Run the working end down the length of the blade towards the blade tip; and loop the rope

around the blade two times, ~2feet from the tip. Again secure the working end to this new

standing part with two opposing half hitches.

12) ~1ft from this new knot, tie a loop in the working end. Clip the carabineer around this loop and

around the lift line. This secures the tip of the blade to the lift line, and allow the tip to “trolley”

down the ground crew as they lower the blade.


13) Remove blade from the alternator, the ground crew must leave slack in the line during removal.

Then allow the ground crew to lower it to the ground.

14) Gently loosen the come-along, keeping some tension. Allow the alternator to slowly rotate until

the next blade is pointing down. Then tighten the come-along again.

15) Repeat steps 10 through 14 to remove and lower the two remaining blades.

16) Once the third blade is on the ground, before the knots are untied, mark with tape the location of

the stopper knot (that runs into the pulley) and the slip knot (immediately under the root pad).

After the LE tape is repaired for all three blades, these knots and the distance between them will

need to be recreated. The knots do not have to be untied. The two slip knots can be loosened

and slipped off.


B. Leading Edge Tape Replacement

NOTE: Carefully maintaining blade balance is a necessity throughout this process.

Ensure that your process is repeatable from blade to blade.

1) Set up the leading edge replacement workstation with the following:

a. Two sawhorses: one with padding on the crosspiece and one with two scrap pieces of

lumber screwed vertically to the crosspiece about 6inches apart.

b. A leading edge tape replacement kit (which includes three strips of leading edge tape, cut

to 8.5ft).

c. Fresh razor blades.

d. Lacquer thinner.


e. Gloves to prevent skin irritation from the lacquer thinner.

f. A measuring tape

g. Two cans of outdoor enamel spray paint (one can may be sufficient depending on the

painter)

h. Scotch Brite 7447 (an abrasive hand pad)

i. If there is any erosion in the fiberglass of the blade, you will also need:

i. Dynalite by Dynatron (Or equivalent material; this is what our blade techs prefer.

May be found at autoparts store.)

ii. Straight sander, ideally with varying grits of sandpaper: 36, 80 and 150.

2) Set the blade up on the sawhorses so that the root end of the blade is resting between the two

vertical peices; the trailing edge should be pointing to the ground and gently resting on the

padding of the second sawhorse.

3) Find the root end of the leading edge tape, and peel it off the blade. All leading edge tape needs

to be removed before it is replaced.


4) Once the tape is removed, you will notice some adhesive residue left behind on the blade. This

should be removed using denatured alcohol and the Scotch Brite 7447 pads. Apply the lacquer

thinner along the entire length of the blade where the leading edge tape was used, using the pads

to rub off the adhesive.

NOTE: Lacquer thinner may damage blade paint. Minimizing this damage will save you

additional painting later.

5) Pay special attention to the tip end of the blade when removing adhesive. This area must be

quite clean. If necessary, use a razor to help remove adhesive and smooth the blade tip.


6) You will notice a small ridge where the existing paint stands above the bare fiberglass. Using a

razor, scrape down the edge so that the transition between painted blade and bare fiberglass is

smooth.

NOTE: Hold the razor blade so that it is perpendicular to the blade. You want scrape

along the blade, not slice into it.

7) If the fiberglass of the blade has some minor damage/pitting from erosion, you can use Dynalite

by Dynatron (or equivalent material, this is the stuff our blade techs like) to fill in the damaged

areas. Once cured, you can use a straight sander in "parallel to blade length" motions to smooth

the material to the original leading edge shape. Start with a rough grit, like 36, and very lightly

remove the bulk of the material. Then switch the 80 grit, and then 150 grit, to attain a smooth

finish to which the tape can adhere. Once you are finished sanding, you will need to clean the

surface with lacquer thinner once more.


8) Measure 102 inches from the blade tip towards the root, and lightly mark the blade. In the next

step, you will start attaching the tape at this point, and work towards the tip.

NOTE: On some older blades, you will replace more leading edge tape than was

removed.

9) Taking care not to touch the sticky side of the tape in any way, peel back approximately 2 inches

of the tape backing paper. Adhere the new tape beginning at the mark from Step 8. Apply only a

straight, narrow strip of the middle of the tape to the leading edge of the blade. Do not fold either

side of the tape down until the entire length of tape has been applied to the blade, just allow the

edges of the tape to hang in air above the windward and leeward sides of the blade.


10) Once the initial portion of tape has been secured (only adhering the center strip of the tape), peel

back about one foot of tape, and apply in the same manner; again, just the center strip. Be very

careful to avoid air bubbles while applying tape. Maintain as little tension as possible on the tape.

11) Continue applying tape, one foot at a time, until the tip end of the blade has been reached. There

should be enough tape that about 4” to 6” of tape hangs off the tip end of the blade.


12) After the center of the tape is completely attached to the leading edge, fold the tape on the

windward side of the blade down (starting at the root end of the blade), and then the leeward side

down. There must not be any wrinkles in the tape. It is easiest to fold the tape down and rub it

onto the blade using the palm, covered with a shirt sleeve or similar cloth.

13) After the tape has been fully engaged along the length of the blade, you will notice micro-bubbles

under the tape. These must be burnished. Use a hard, smooth object (like a credit card or a

scrap piece of rounded and smooth metal) and rub the tape to remove the micro-bubbles. There

is a noticeable difference between a portion of the blade that has been burnished and one that

has not, as seen above. Make sure to burnish the entire length of the tape to ensure proper

adhesion.


14) Once burnishing is complete, you can use a razor to trim off the overhanging portion of tape at

the tip. Trim using a brand new razor, at a 45° angle to the tip of the blade. This will give a

chamfered edge to the tape at the blade tip.

15) Use canned spray paint to apply a couple of layers of outdoor rated enamel to the new tape.

16) Repeat the leading edge replacement procedure for all three blades.

C. Blade Installation

1. Using the value recording from Step 17 of Section A (probably around 3ft), recreate the knot work

from Steps 10, 11 and 12 of Section A on the first blade to be lifted.

2. The ground crew will trolley the blade up the lift line, in reverse fashion to how it was lowered

previously.

3. Once the man on the tower receives the blade, it is lifted and “hung” on the lower two studs of the

alternator; the upper two studs for this blade are probably not yet making contact (This is due to

the alternator being “tilted back” eight degrees). At this point, pull in with both hands and push

out with the foot. Once the blade is properly aligned it will fall into place. Do not force it.


4. Once the blade is against the alternator, install the two stainless washers and the two blades nuts

on the thin root pad side of the blade only. Snug the two nuts.

5. Untie the rope from the blade.

6. Now you must rotate the alternator; indexing it around so that the next set of empty studs is

towards the bottom and can receive the next blade. The ground crew can carefully apply the

majority necessary force; but not enough to turn the alternator, rather being a counter balance.

This allows the person on the tower to apply the last bit of force and accurately position the

alternator.

a. Run the rope up over the top of the alternator. The rope must be lying on the curved,

side of the alternator and must not overlap the lifting sling (most likely the rope will be

towards the front and the sling towards the back).

b. Run the rope under the alternator, behind the attached blade, and up the side and attach

the rope to one of the studs in the next group.

c. Loosen the come-along, enough to allow rotation but maintain some friction.

d. The ground crew carefully adds their rotational force, as the person on the tower lifts the

attached blade only 1/3 of a rotation. The lifting slip will need to be pulled forward

occasionally, as it will try to slide towards the back edge of alternator during turning.

e. Once the next group of empty studs is in the lower most position, tighten the come-along.

7. Lower the rope to ground, and repeat Step 1 through Step 5 for the second blade.

8. Repeat all of Step 6 to index the alternator around so the final set of empty studs is in the lower

most position. Position the rope around the alternator in same direction as just performed in Step

6, so as to rotate the alternator in the same direction.

NOTE: EXTREME CAUTION AND GOOD COMMUNICATION MUST BE USED WHILE

THE GROUND CREW APPLIES THE COUNTER BALANCING FORCE NOW THAT

TWO BLADES ARE ATTACHED. THE BLADES MUST BE CAREFULLY AND SLOWLY

ROTATED ONLY 1/3 OF A TURN. ONCE BOTH BLADES ARE UP IN THE “Y”

POSITION, THE SYSTEM IS BALANCED AND UNSTABLE. ADDITIONAL

ROTATIONAL FORCE CAN CAUSE THE SYSTEM OVER ROTATE AND SWING

DOWN.

9. Lower the rope to ground, and repeat Step 1 through Step 5 for the final blade.

10. Install the blade clamp plate (may not be present in older systems), and blade nuts on the thick

side of the root pad.

11. Torque all blade nuts to 150ft*lbs.

12. Install spinner.

13. Perform system inspection, per the relevant tower installation manual (see

http://www.bergey.com/Technical ).

14. Use rope/pulley to lower relevant tools.

Date post:	14-Mar-2018
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