Wind Blade Failure Identification and

PreventionGary Kanaby

Director of Sales/Wind Energy MFG Wind

Molded Fiber Glass Companies

www.compositesshow.org

January 29-31, 2013 Orange County Convention Center, Orlando, Fla.

3

Factory Repairs and 

Reconditioning of  Components

Factory Repairs and 

Reconditioning of  Components

Spare and Replacement 

Parts for Legacy Equipment

Spare and Replacement 

Parts for Legacy Equipment

Field Repairs and 

Maintenance Services

Field Repairs and 

Maintenance Services

Composite Component 

Manufacturing for OEM’s

Composite Component 

Manufacturing for OEM’s

Cradle to Grave Composite Capability for Wind Energy

Field O&M services for wind farm operators• After-market and warranty

work

Engineering Engineering & Research

Lab

Four factories fabricating components for wind energy

Two facilities open to factory repairs

Reverse engineering and custom tooling

Presentation OutlinePrevention of blade problems begins in Design

Carried out in ManufacturingAnd continues through O & M

Size has challenged blade building. Typical blade design and fabrication methods. Blade building challenges. Factory Inspection techniques. On site inspection at delivery and installation. End of Warranty inspection. Regular scheduled maintenance. Blade issues in the field. Repair procedures are carefully pre-planned and

managed.

Design Considerations• Design for manufacturability.• Include up to date technology.

• Advanced materials.• Lightning protection

systems.• Protective coatings (and ice

shedding)• Lessons learned from past

failures.• Rigorous testing.• Designed for proper wind

regime.• Ample design margins.

Wind Technology Testing Center(Boston)

30 Years of Blade Scaling

170 kgs…

10,000 kgs.

75m Blade

Source: Euros

Source: Siemens

Typical Blade Construction

Fiber Placement

Source: Siemens

1.5 - 2 tons of glass placed in mold with proper positioning within ½ shift.

Errors in positioning could result in blade failure.

Infusion

Source MFG South Dakota

• Movement in the glass as vacuum is applied or

• Non infused areas are problems to avoid.

Mold Closing

Source: LM Glasfiber

150 meters or more of controlled bond line.

Robotic Cutting & Drilling

Source MFG South Dakota

• Blade facing and hole positioning within thousands of an inch.

Robotic Paint Booth

Source MFG South Dakota

• Coatings need to last 20+ years.

Incomplete Infusion

• Thermographicimaging can be used to find dry spots in the laminate or voids in the core bonding.

Movement during vacuum

Wrinkles in fabric a big concern.

Ultrasound scanning

Barriers to Entry and Competing in the Market

• Huge capital investment.• Warranty risk.• Absence of long term contracts.• Uncertainty of the market due to short

extensions of tax incentives and lack of a long term energy policy.

• Unfair advantage from foreign suppliers.

Onsite Inspections and Repairs

• New site delivery and construction

• End of warranty

• Last chance for warranty claim.• First chance to find lighting or other damage.• Documentation of blade condition-start of data-base.

• Periodic Scheduled• Blades should be re-inspected & repaired periodically.• After an event.• Sampling or turbines that have had strikes previously.

• Protection for LE after repairs.

• Lightning Protection System (LPS) verification.

New site Transportation and Installation Damage

• First chance for outside inspector to examine the blades.

• Defects are taken care of while blades are on the ground and least costly.

• If defects are not corrected, a small problem can lead to a future failure.

Ground Inspections

• Inspections from the ground save time and money.

• If defects are found uptower inspections can verify damage.

400mm lens from ground

Uptower Inspections/Repairs

• Using suspended work platforms, technicians access the blades up tower.

Inspect at End of Warranty

• Verify condition at end of warranty with ISP.

• Report and database is created.• Warranty repairs are

completed before hand off.• Non-warranty repairs can

also be completed at the time of inspection.

• Suggest that both Dynamic Mass and Aero assessment is made (sampling) Assessment inexpensive Corrections are more costly

Benefits of Scheduled Maintenance • Increased availability.• Reduce/eliminate catastrophic failures. • Reduce/eliminate large repairs .• Reduced crane/mobilization cost.• Increased aerodynamic efficiency.

Leading Edge Erosion

Correct Pitch Angle

What is Scheduled Maintenance?

• Scheduled during non-productive season.

• Inspections from the ground.• Inexpensive and easy.• Use camera to document.

• Up-tower. • Verification of damage.• Repair are completed immediately.

• While up tower. • Check LPS.• Open drain hole.• Protective LE coating.

Leading Edge Erosion• LE erosion is most common blade

aging issue.• Monitor progress.• Decide when to address it.

• Repairs• Easily repaired up tower. • LE shape can be verified with

templates.• While doing the repairs add

protection.• LEP • Open drain hole• Protective LE coating

Lightning Damage

Digital Low Resistance Ohmmeter Test each receptor

Lightning System Testing

Lost Revenue

• Reduced energy as result of poor aerodynamics & pitch errors

• Blade vibrations damage gearbox.• Reduced energy for shut down during icing & high

winds.• Lost revenue due to turbine non-operation while

waiting for repairs to be completed.• Access to the blade using crane/lift.• Actual cost of the needed repair.

Rotor Imbalance

• Dynamic Rotor Balancing can detect and correct mass imbalance.

• Mass imbalance can cause excessive main bearing wear and gearbox problems.• Moment varies due to uneven

blade masses or distribution.• Hub imbalance or flange errors

• Are the tips of the blades equidistant?

• Bent shaft.• Blades have absorbed oil or

water.

Aerodynamic Imbalance

• Blades are producing varying power.• Uneven blade profiles.

• Built wrong• Repairs• Erosion

• Coning angle errors.• Pitch angle varies from blade to blade.

Aero-Dynamic Blade Balancing

Condition Monitoring

Active Condition Monitoring• “Smart” blades send information to the controller• If strains are too high, angle of attack can be

adjusted.• Detection of major degradation of laminate or bond

can shutdown machine.• Fiber- optic strain gauges run span wise.

• Shutdown and start up during icing is controlled, minimizing downtime.

• Sensors in root detect imbalance.

Service Challenges

• Safety.• Qualification and Acceptance by wind farm own• Training extensive.• Managing from afar.• Quality Control.• Engineering support.• Retention of technicians during slow season

Summary• Blade failure prevention begins at the design• Through factory inspections defects can be

found and corrected-or the blade is rejected.• Upon delivery third party inspections & repairs

can find & remedy defects before operation.• End of warranty reveals the blade’s state after

two years.• Inspections throughout the life of the rotor will

identify defects that can be addressed before they progress to catastrophic failure.

• A fully functional LPS will limit lightning damage.

• Rotor mass & aerodynamic balance can prevent premature failures.

The End

www.compositesshow.org

January 29-31, 2013 Orange County Convention Center, Orlando, Fla.

Gary KanabyMolded Fiber Glass CompaniesWind Energy Services Companygkanaby@moldedfiberglass.com619-778-7213www.moldedfiberglass.comwww.windenergyservicesusa.com