IEC 61400-5 Table G.1: Acceptance Criteria

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

TL;DR Delamination capped at 6 mm in any direction. Porosity cluster capped at 3 mm diameter and under 3 % area. Dry laminate and resin starvation not permitted at any size. Wrinkle capped at 3 degrees from nominal, foreign inclusion not permitted.

Table G.1 is the acceptance table, and it is where a scan result becomes a decision. Each defect class carries a limit, and the limits are not all the same kind of number. Some are sizes, some are angles, and some are absolute. Reading the table correctly is what stops a scan from being interpreted by feel.

What the standard covers

The table covers the laminate defect classes a blade scan will meet, delamination, porosity, dry laminate, wrinkle and foreign inclusion among them. Each carries its own limit and its own basis, so the disposition of an indication depends on which class it belongs to rather than on its amplitude alone.

What it demands

Delamination capped at 6 mm in any direction
Porosity cluster capped at 3 mm diameter and under 3 % area
Dry laminate and resin starvation not permitted at any size
Wrinkle capped at 3 degrees from nominal, foreign inclusion not permitted

How it lands on a blade scan

The limits differ in kind, so the scan has to return the right quantity for each. Delamination needs a size in any direction, porosity needs a diameter and an area, a wrinkle needs an angle from nominal, and dry laminate and foreign inclusions need only a yes. That is why one pass carries several channels, an amplitude map for the planar and dry indications, a volumetric channel for porosity and a ply-boundary reading for waviness. A single 64-element array steering through 40-70° on a 256-channel system collects them together, and the 6 mm squared flat-bottom hole at 20 mm depth is the reference that ties the amplitude channel to a known sensitivity.

How to apply it to a blade

Run these checks in order. By Step 5 the scan plan has the threshold, the geometry and the record it needs.

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 does Table G.1 cap delamination and porosity at?

Delamination is capped at 6 mm in any direction, and a porosity cluster at 3 mm diameter and under 3 % area. The porosity limit is tighter than the delamination floor, so the two are not interchangeable.

Which defects does Table G.1 not permit at all?

Dry laminate or resin starvation, and a foreign inclusion. Both are listed as not permitted, so there is no size below which they become acceptable and no monitoring window for either.

Why does a wrinkle limit read in degrees?

Because a wrinkle is out-of-plane waviness, so its severity is a deviation from nominal rather than a length. Table G.1 caps it at 3 degrees, and the scan has to return an angle from the ply-boundary shift to apply that limit.

How does a scan enforce several limits at once?

By carrying the channels the limits need. An amplitude map serves planar and dry indications, a volumetric channel sizes porosity, and the ply-boundary reading gives the wrinkle angle, all collected in one pass on a 256-channel system.

Bottom line: Table G.1 turns a scan into a decision by giving each defect class its own kind of limit, so the method has to return the right quantity and not just a signal. Size delamination in any direction, size porosity as a diameter, read the wrinkle as an angle, and treat dry laminate and inclusions as absolute.