What a blade claim turns on
Most blade claims resolve around four findings, and the investigation should be scoped to produce all four with a stated level of confidence:
- The initiating cause. What failed first, as distinct from the damage that followed. A spar cap that buckled after a trailing edge opened is a consequence; the trailing edge bond line is the cause.
- When the cause entered the blade. In design, in manufacture, in transport or installation, in operation, or in a prior repair. This is the finding that decides whether a defect exclusion bites and whether the manufacturer's warranty is engaged.
- Whether the cause is isolated or serial. A serial manufacturing defect present across a plant's production is a fleet exposure, not a single loss. It changes reserving, it changes the conversation with the reinsurer, and it changes what the owner can be asked to do about the remaining blades.
- What the evidence supports, suggests and cannot determine. A report that presents everything as established will not survive the manufacturer's expert. One that separates the three is the one the adjuster can rely on.
Cause, defect exclusions and the order of events
Construction and operational policies commonly exclude loss caused by a defect in design, materials or workmanship, in varying forms; the London Engineering Group wording that appears in many construction all risks policies grades the exclusion from the defective part only to all consequential damage. Whichever form applies, the exclusion turns on the same technical facts: was there a defect, what did it consist of, and what damage flowed from it as opposed to from an external event.
The wind turbine blade manufacturing process is manual where it matters, and most structural defects in a blade are manufacturing defects: a laminate wrinkle over a ply drop, dry fibres where the resin front stopped, a starved bond line, a badly cured adhesive. Those are found by reading fracture surfaces and cutting cross-sections near the origin, and by comparing what was built with the design basis and the production records. Lightning, transport damage, an extreme wind event or an operational excursion leave different evidence. The investigation's job is to establish which, and the adjuster's job is to make sure the investigation is scoped to do so before the evidence is disturbed.
The manufacturer's root cause analysis is the first document, not the last
In nearly every blade claim the manufacturer's root cause analysis arrives first. It is written by the party whose product failed, with data nobody else holds, and it will be technically competent. It is also the document the manufacturer will rely on in any warranty or recovery discussion. An insurer who accepts it without independent review has accepted the other side's position on the facts that decide the claim.
An independent blade expert instructed early can attend the forensic inspection of the failed blade, witness the laboratory analysis on which the manufacturer's conclusions rest, and put the technical questions while the samples are still on the bench. In our experience that is the point at which an unchallenged assumption becomes a finding that is hard to unwind later. Reviewing the finished report is useful; being present when it is written is worth more.
What to secure in the first days
The quality of the eventual report is fixed in the first week. Evidence that should be preserved before any repair, clean-up or restart:
- photographs and drone imagery of the blade and the debris field as found
- SCADA data around the event: wind speed, rotor speed, pitch angle, power, alarms and turbine state
- lightning detection records and the strike log for that turbine
- inspection, repair and maintenance records for the failed blade and its two neighbours
- blade serial number, plant, mould, production date and any non-conformance reports
- the fracture surfaces, kept dry, unhandled and photographed before removal
A loss adjuster who asks for this list on day one will be able to instruct an investigation that can answer the cause question. One who receives a blade six weeks later, after it has been cut up for transport, often will not.
The serial defect question and the rest of the fleet
Once a manufacturing defect is established, the next question is exposure. A defect that the process produces will be present in other blades built by the same process, at the same plant, in the same period. The evidence for a serial defect is a repeatable signature: the same location, the same laminate detail, the same load path, and usually the same production window. Confirming it needs the failed blade's cross-sections, the production records, and an inspection of a sample of the population by a method that can actually see the defect. For a wrinkle buried in a spar cap that means ultrasonic testing, not a drone flight.
The commercial consequence for the insurer is that a single claim becomes a fleet position: which turbines may operate, which blades need inspection, and what the manufacturer is being asked to do under warranty. An independent serial defect assessment gives the underwriter, the owner and the lender the same technical basis for those decisions, which is what allows them to be taken quickly.
Recovery and the expert's role in a dispute
Where the cause is a defect, the insurer will usually look to the manufacturer, and sometimes to an installer or a repair contractor. That conversation is technical before it is legal, and it is won or lost on the quality of the investigation. A report written to be understood by non-engineers and to withstand examination by engineers, with the confidence in each conclusion stated, is the document that carries a recovery.
If the matter proceeds to arbitration or litigation, the same expert who attended the inspection and witnessed the laboratory work is the one best placed to give expert evidence. We act for one side of a dispute; where both sides approach us on the same matter, we say so and decline the second instruction.
What underwriters can ask for before the loss
Underwriting blade failure risk is easier when the blade population is understood before a claim. Questions worth asking at placement or renewal:
- which blade type and which manufacturing plant supplied the fleet, and whether that combination has a published or known defect history
- what the inspection regime is, by what method, and how often
- whether any blades have been repaired, by whom, and to what documented method
- whether the inspection reports have been reviewed by anyone independent of the inspection provider
None of this requires the underwriter to become a blade engineer. It requires the questions to be asked and the answers to be read by someone who can.
Frequently asked questions
Does a manufacturing defect always mean the claim is excluded?
No. It depends on the policy wording and on what damage flowed from the defect as opposed to from an external event. The technical investigation establishes the facts; the wording determines what follows from them. The two should not be confused, and the investigation should not be scoped by the hoped-for answer.
How soon should an independent expert be instructed?
Before the failed blade is moved, and before the manufacturer's laboratory work begins. The first days decide what can be established later, and the laboratory analysis is where the mechanism is fixed.
Can one blade failure become a fleet exposure?
Yes, where the cause is a defect the manufacturing process produces. Establishing that requires the failed blade's cross-sections, the production records and an inspection of a sample of the population by a method that can see the defect.
What should the final report contain?
The initiating cause and the sequence of events; when the cause entered the blade; whether it is isolated or serial; a clear separation of what the evidence supports, suggests and cannot determine; and a plain-language summary for the people who will decide the claim.
How Apex Wind can help
We are an independent blade engineering consultancy in Denmark, working for insurers, loss adjusters, brokers, owners and lenders. We are independent of every turbine and blade manufacturer, we sell no repairs, hardware or monitoring products, and we take no referral fees. Our blade failure investigation and root cause analysis covers the forensic inspection on site, attendance at the manufacturer's laboratory analysis, review of their root cause analysis and the serial defect assessment across the fleet. Where a claim becomes a dispute, we provide expert witness and dispute support. If a blade has failed on a risk you write or adjust, contact us while the evidence is still on site.