Fleet-Scale Blade NDT Across Mixed Turbine Models

What this stage covers

The scope is a whole fleet rather than a blade. A crawler that deploys in about 15 minutes per blade with one technician turns a farm campaign into a repeatable routine, and a standardised protocol makes a scan on one OEM’s blade comparable with a scan on another. That comparability is what turns a set of readings into fleet trending.

What the inspection includes

• A single technician deploying the crawler in about 15 minutes per blade, so a fleet campaign does not stall on crew waiting
• One scan protocol across mixed OEM blades so the data is comparable rather than machine-specific
• Fleet aggregation into trending dashboards with automated anomaly flagging
• Integration with ERP and CMMS so a flagged blade enters the maintenance plan rather than a separate report

Where the value sits

The value at fleet scale is comparability. Manual readings vary 15-25 % between operators, and across a hundred turbines that variation is larger than most defect growth, so a mixed fleet cannot be trended from hand-held data. A standardised crawler pass repeats within plus or minus 0.5 mm and indexes at plus or minus 0.1 mm, so a blade scanned this year sits on the same basis as one scanned last year and on a different turbine model. The scan protocol is what makes a fleet a dataset rather than a pile of site reports.

How to plan this stage

Run these checks in order. By Step 5 the scan, the threshold and the record are aligned to the stage.

1. Fix the acceptance threshold. Start from the threshold the zone carries, not from the method you happen to own. IEC 61400-5 Section 11 asks for volumetric detection of indications 6 mm and larger in the laminate plane, and DNV-ST-0126 tightens the leading edge to 3 mm, so the threshold is set before the probe is chosen.
2. Read the geometry off the drawing. Measure the thickness and the curvature the probe has to travel. A spar cap up to 80 mm of unidirectional laminate and a root transition of changing radius are two different scan problems, and the radius decides how the array is coupled.
3. Choose the modality pair. Pick modules by defect geometry, not by habit. PAUT images planar separations that lie parallel to the plies, TOFD catches volumetric clusters whatever their orientation, and running both on a 256-channel system puts the two mechanisms in one pass.
4. Automate the scan path. Put the probe on an encoder-driven carriage and let the path, not the technician, set coverage. A 600 mm spar cap falls to one longitudinal pass at 500 mm/s on a linear array, where a single-element probe needs 20 parallel passes and runs about five times longer.
5. Lock the evidence chain. Write the coverage map, the daily calibration and the indication log to the blade serial while the scan is running. It is the difference between a 3-day type-certification audit and a 3-hour document review, and it is what ISO 9712 qualification is there to sign.

Values quoted here come from the same verified data the product pages carry, so this page and its sources agree line for line.