That was it. The vial stoppers were micro-deflecting during air freight, opening transient channels—channels that closed before any lab test could catch them.
Her team had followed to the letter. Section 6.2: container-closure integrity testing. Section 7.3: method selection based on product risk. They had chosen helium leak detection, the gold standard. pda technical report 27 pdf
She reopened TR 27 to Chapter 9: Package Integrity Throughout Shelf-Life . Buried in a footnote was a warning she had skimmed past six times: “Leak rates measured under lab vacuum may not predict real-world flexing during transport.” That was it