Post-Assembly Full-Volume Scan: The Last Gate

Author: RAS Thermal Co., Ltd. · Updated 2026-10-07

TL;DR Full-volume scan of the completed shell before painting. Cap, web and trailing-edge results consolidated into one record per blade serial. The same 6 mm volumetric floor from Table G.1 applied across the zones. A traceable record from lay-up to field service, ready for a certification review.

The post-assembly scan is the last gate before the blade is finished and shipped. It is run on the completed shell before painting, and its job is to confirm the whole assembly rather than a single joint. By this stage the coverage from the earlier stations either agrees or it does not, and a gap here is more expensive than a gap found earlier.

What this stage covers

The scope is the assembled shell, scanned as a whole before finishing. The cap, the web joints and the trailing edge are brought together into one dataset per blade serial, and the result is the record the blade carries out of the plant. By the final gate the earlier stations have already produced most of the evidence, and this pass confirms it on the assembled article.

What the inspection includes

Full-volume scan of the completed shell before painting
Cap, web and trailing-edge results consolidated into one record per blade serial
The same 6 mm volumetric floor from Table G.1 applied across the zones
A traceable record from lay-up to field service, ready for a certification review

Where the value sits

The gate is about closing the chain rather than adding a method. By the time the blade reaches it, the cap was scanned within 30 minutes of infusion and the joints were checked on the open shell, so the final pass confirms those results on the assembled article and consolidates them into one record per serial. That consolidation is what a certification review uses, and it is why a chain that agrees end to end can turn a 3-day audit into a 3-hour document review. A blade that leaves with an unbroken record is a blade that can be compared with itself in service.

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.

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.
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.
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.
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.
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.

The numbers below are drawn from the equipment records and field campaigns this site already publishes, not from a generic catalogue.

Frequently Asked Questions

What is the post-assembly scan for?

Confirming the earlier results on the assembled shell and consolidating them into one record per blade serial. By this gate the cap and the joints have already been scanned, so the pass closes the chain rather than opening a method.

Which zones does it cover?

The cap, the web joints and the trailing edge together, judged against the same Table G.1 limits as at the earlier stations. Bringing them into one dataset per serial is what makes the record usable in a review.

Why is this gate more expensive to fail?

Because the blade is almost finished. A gap found here cannot be closed by a station repair the way an early finding can, which is why the earlier stations exist to make this gate a confirmation rather than a discovery.

How does the record help in service?

It gives the blade a baseline. A field scan years later is compared with the as-built record, so a delamination or a crack is measured against a known origin rather than against an assumption about what the blade was like when new.

Bottom line: The post-assembly scan closes the evidence chain rather than adding a method, confirming the earlier stations on the assembled shell. Consolidate cap, web and trailing edge into one record per serial, and the blade leaves the plant with a baseline its field scans can be measured against.