A repair is the one moment a blade is guaranteed to be touched. And the one moment nobody measures it.
Measuring the blade before, during and after the repair you have already scheduled. A structural signature either side, and a physical record of what the blade experienced in between.
A blade is flagged for repair. Then what?
Most repairs never leave the turbine, and those are the frequent ones: rope access or platform, repaired in place. The repairs that do come down are rarer and carry far more handling. Dismount, lower, move, repair, move, lift, remount, with the steps and the order varying by job. Neither route is measured, before, during or after.
Before the campaign
- The inspection tells you what the surface looks like. It does not tell you how the blade behaves.
- So there is no measured reference point that exists before anyone touches the blade.
- If something looks different at the next inspection, there is nothing to reason with about when it started.
During the campaign
- Dismount, lowering, transport, workshop handling, lift and remount.
- Each is a high-consequence operation on a fifty to hundred metre composite structure.
- None of it is recorded in a form anyone can point to afterwards.
Without detailed measurements, potentially damaging load events can go unnoticed.Fraunhofer IWES on blade transport and handling, February 2026
It is a recurring claim category
Handling damage during lifting and transport turns up repeatedly in insurance claims across the industry. It is not an exotic failure mode, and it is not confined to one contractor or one region.
The range of damage is wide
Recorded damage runs from surface scratches through to primary structural members requiring blade replacement. Damage that starts small during handling can grow in operation.
Today it is settled on paper
Contract wording, an independent surveyor, a joint survey once the disagreement has already started, photographs and expert opinion. All of it useful. None of it measures the blade.
Most of the published evidence concerns new blades in transport rather than repair-driven handling. We have not documented a repair-driven case of our own, and we would rather establish that with an operator than imply we already have.
One story about one repair
Structural signature
How the blade behaves compared with its two siblings on the same turbine, in the months between the finding and the repair.
Physical record
Shock, orientation and movement through dismount, lowering, transport, repair, lift and remount, mapped onto the phases of the job.
Structural signature again
The same measurement once the blade is back in service and has run long enough, compared with the picture from before.
Two modules. Take one, or both.
Module A measures the blade. Module B measures what happened to it. Where a blade comes down, both apply. Where it is repaired up-tower, Module A alone still answers the before-and-after question.
Condition comparison
A structural signature either side of the repair, built during the wait you already have.
- Installed during the waitOptical accelerometers retrofitted into the blades, connected by fibre to a unit in the hub. A category 3 or 4 finding typically leaves three to twelve months before the repair.
- One score per blade per weekFrequency drift and vibration energy, always compared at the same rotor speed, computed on a fixed weekly cycle.
- Referenced three waysAgainst the blade's own history where we have it, against its two siblings on the same turbine, and against peers in the same farm.
- Repeated after the repairOnce the blade is back in service and has run long enough, the same score is produced and compared with the picture from before.
Handling record
A factual record of what the blade physically experienced during the campaign.
- Placed before the blade comes downBattery-powered units inside the blade, so the record starts before the highest-risk step rather than after it.
- Recording through the whole operationShock and impact with peak value, axis and time. Orientation and movement. Sustained vibration in transport.
- Mapped onto the phases of the jobAn exceedance is attributed to the lowering, to road transport or to the lift, rather than to somewhere in the process.
- Removed and reusedThe hardware comes out after remounting and goes to the next campaign. It is never a capital purchase for you.
Four questions nobody can answer today
Blade or rotor engineer
Did the blade come back behaving like a normal blade of its type, or is it still an outlier?
Campaign manager
Can I show that this campaign was executed within limits, and where the process can be improved next time?
Health and safety
Every precaution on my lifting risk assessment is procedural. Can any of them actually measure something?
Technical asset management
After a repair, what is this blade now worth, and what did the repair actually restore?
A detective control on a document that has almost none
On the pre-campaign risk assessment, the lifting rows carry the highest remaining risk on the page. Every precaution available today is procedural, and none of them measures anything.
Today's precautions
- Use certified lifting equipment
- Work to the lifting plan
- Follow the rigging plan
- Keep personnel out of the drop zone
What we add
- A threshold agreed before the job, in writing
- A measurement during the operation
- A defined response if the threshold is exceeded
- Evidence that feeds the next assessment
What we claim, and what we do not
Tarucca does not decide whether a blade is damaged, safe or fit for service, and does not issue a go or no-go. That stays with you and with the people who inspect and certify. We measure, and we report what changed.
We do claim
- We can see that a blade's behaviour has moved relative to its own history and its peers.
- We can record what physically happened to the blade during the campaign.
- We can compare the picture after the repair with the picture before it.
- We can do this on a blade we have never measured before, because the siblings provide the reference.
We do not claim
- We cannot say from the measurement what the damage is. We can say that something changed.
- A handling record proves what happened, not what it caused. An exceeded threshold is not proof of damage.
- Monitoring does not prevent a dropped load. The claim is about damage carried forward undetected.
- Module A needs the turbine to run. A stopped or heavily de-rated turbine gives us little or nothing before the repair.
The questions that usually come up
Why not just inspect more often?
Inspection finds and classifies surface damage, documents leading-edge erosion, gives a defensible visual record, and is what your acceptance process is built on. We are not proposing to replace any of that.
What it cannot do is tell you how the blade behaves, be present during the lift and the transport, give you a reference point that existed before the campaign, or compare the blade with its own siblings. We are proposing to measure what inspection cannot see.
Where do the handling thresholds come from?
A handling report is only as good as the limits it is judged against, and we do not invent them. We work from your blade manufacturer's own handling instructions for lifting, clamping and transport, from recognised classification of shock and vibration severity for transported goods, and from published laboratory work on what handling loads do to blade structure.
Once several campaigns have been recorded, your own fleet becomes its own reference. Thresholds are agreed with you in writing before the campaign, and we do not change them afterwards.
Can you even place equipment in the blade? What about warranty?
It may touch your warranty, and your service contract may give the manufacturer's organisation exclusive access to this work. Where that is the case there is more than one route:
- Through you, where you self-perform or have the contractual freedom to bring your own equipment.
- Through your service contractor, with Tarucca as their supplier. You still ask for it and still receive the report.
- Through the repair or transport provider, who has their own interest in showing that their work stayed within limits.
- On the transport frame rather than inside the blade. Fewer obstacles, and we would say plainly what that costs in data quality.
What if the turbine is already stopped?
A category 5 finding leaves no measurement window, and we will say so rather than sell you something that cannot work. The handling record still applies: the blade still has to come down, travel, be repaired and go back up, and that is still unmeasured.
Once the repaired blade is back in service, the score establishes a reference for the future even without a pre-repair picture. What we will not do is claim a before-and-after comparison we cannot produce.
Why optical sensing rather than conventional accelerometers?
Optical accelerometers retrofitted inside each blade, connected by fibre to a single unit in the hub, mean no electronics in the blade and no metal path to the tip. The measurement keeps working through a lightning strike.
Conventional electronic sensing is well proven, widely deployed and lower in unit cost, and we are not claiming better damage detection than a good conventional system. We are claiming a sensing path that survives the electrical environment it sits in.
Who owns the data?
You do. Measurements from your turbines are yours, and we say so in the contract. We may use anonymised, aggregated characteristics only, and only with your written agreement. Storage location, including whether the data stays inside the European Union, is agreed before the campaign. At the end you receive the raw record as well as the report, and only the people you name see it.
What would we recommend after the repair?
Once Module A is installed and the blade is back in service, the sensible thing is to leave it there. No new installation and no new campaign, and you get continuous condition monitoring on all three blades of that turbine, history in place for the next repair on that turbine, and a before-and-after comparison within hours of a lightning strike.
That is a recommendation, not a condition. A first campaign stands on its own.
Advisory alongside your own process, scored against reality
Best fit is a category 3 or 4 finding, a repair three to twelve months out, and a turbine still running.
Agree scope
Thresholds set in writing, access and warranty position confirmed, and the operating window during the wait agreed in advance rather than requested later.
Install
Module A during a planned visit. Module B units placed before the blade comes down.
Measure and report
A weekly score through the wait, a continuous record through the campaign, one report per blade and per campaign, plus a visual replay of the blade's movement.
Score us
At the end we compare what we said with what was actually found, in writing. Then you decide whether to scale it, adjust it or stop.
No interference with your operations, and no change to your existing procedures. Our output sits next to your process and never replaces anyone's judgement.
When is your next scheduled blade repair?
We would like forty-five minutes with your blade engineering and campaign people. We have questions we cannot answer from the outside, about warranty and access, about what your turbines do while they wait, and about how your risk assessments are built. If it goes well, the next step is one campaign, advisory alongside your own process.
