Hi khanhhuyen,
You will need to do a root cause analysis as GMO has stated and as per BRCGS clause 1.1.12 this will be checked at your next audit. Whatever the outcome I would expect to see the following actions.
Corrective Action:
Hold and check the product
Investigate the cause of the failure
Fix and validate the metal detector & re-establish verification procedures.
Preventive Action
Retrain staff and evaluate the effectiveness at training
Increase service frequency and validation frequency of metal detector
Review procedures
Note BRCGS Global Standard for Food Safety Issue 9 Section 4.10 Foreign-body detection and removal equipment, second part of Clause 4.10.1.3:
The site shall establish and implement corrective action and reporting procedures in the event of a failure of the foreign-body detector and/or removal equipment. Action shall include a combination of isolation, quarantining and re-inspection of all products produced since the last successful test or inspection.
Kind regards,
Tony