Joint gap drift during clamping — guide G-18

Defect found during first-article inspection of Guide rail G-18. The J-groove weld showed gap drift under clamping load; joint gap measured at 1.6 mm against a 1.5 mm maximum.

Root cause: the two-point locating scheme allowed the upper flange to rotate under clamping load, opening the gap on the far side of the groove.

Corrective action: Fixture redesign with wider clamp pads.

Disposition: rework and re-inspect. Lesson recorded for drawings using the same locating pattern.