Calibration Intervals · 5 min read
When an Instrument Comes Back Out of Tolerance
An out-of-tolerance result is not a disaster — but ignoring it is. It is the moment your calibration program proves whether it can protect your product and your quality record.
Part of our guide to Calibration Intervals & Program Scheduling.
The required response
When an instrument is found out of tolerance, standards like AS9100 (7.1.5) and ISO 13485 require you to assess the validity of prior measurements made with it and take action on any affected product. The as-found data tells you how far out it was, which drives how far back and how aggressively you must look. This is "reverse traceability," and it is exactly why as-found data matters.
A workable procedure
Quarantine the instrument, record the as-found condition, identify what it measured since its last good calibration, assess whether the magnitude of the error could have caused nonconforming product to pass, and document the decision and any containment. Then adjust or repair, verify as-left, and feed the event back into interval analysis. A calm, documented process here is what turns an OOT event from a crisis into a controlled record.
Common questions
Do I always have to recall product?
Not necessarily — the impact assessment may show the error was too small to affect conformity given your tolerances. The point is to make and document that determination, not to assume either way.