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BLADE INSPECTION & REPAIR


FEATURE SPONSOR


HIGHER INTERNAL RATE OF RETURN = LONGER LIFECYCLE


Blades are the turbine component most impacted by age. Coating, lamination, aerodynamics, lightning protection systems all show increasing failures over time – trailing edge, blade shell, spar, root and lightning protection systems are the parts that are most hit by age.


TURBINE DOWNTIME


Turbine downtime doubles over the years: 2.8 days/year in the first 5 years in operations, 5.3 in the last 5 years – blades can contribute to up to 25% of the downtime, particularly in the second half of the normal turbine life-cycle. Aging hits blades harder than natural events and the consequences of failures are becoming more and more critical.


ASSOCIATED COSTS


Inspections on aging turbines report cracks in the trailing edge panels, transverse and longitudinal, split of the trailing edge bond lines, failures of the web bond lines. The rotation of the blades causes undesired deformations, independently from wind – deformations are the root cause for these cracks.


The total associated cost of repair per year on such failures is around 4 thousand € and represents over 60% of the total blade maintenance budget.


OTHER AREAS OF FAILURE Another typical area of failure is the leading edge: when the blade is distorted in transverse shear, stresses increase in the leading edge area. Solutions to reduce the cross-sectional shear distortion are being made available and are aimed at preventing fatigue cracks thus reducing failures.


However, the main part of the blade subject to failures which could be difficult to recover, leading to the need to replace the blade instead than just repairing it, is the fatigue in the root region, mainly due to the higher gravity induced edgewise loads.


REPAIR TIME


One of the most critical issues regards the time needed to do the repair – for non-structural failures, eTa Blades has developed a UV based resin and patch in tailored kits, enabling a 30mins durable repair.


The company is taking the lead on improving wind turbine efficiency, lower the O&M cost and extend the life-cycle of the turbines. They are developing and testing specific repair and improvement solutions for all the issues stated alongside their main business of re-blading.


eTa Blades


44


www.windenergynetwork.co.uk


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