Nowadays it is state of the art, that manual inspection of random AQL samples is part of the 100% visual inspection. The results are taken into consideration as part of the batch release process. But what happens when the batch fails the AQL test, i.e. the limit has not been adhered to? In this event, it is useful to carry out another 100% visual inspection on the entire batch and do a second AQL inspection. Tighter limits are recommended for the second AQL test. This can be achieved in two ways:
1. Retain the AQL sample number and use the next tighter AQL limit or
2. Retain the AQL limit and use the next higher number of samples.
In any event, the number of possible repetitions of the test must be specified. The ECA Best Practice Guide recommends a maximum of two repetitions. All of the repetitions must be recorded in the batch documentation.
Another frequently asked question in this context is whether the samples for the AQL test can be returned to the batch after a successful test. As a rule, there is no reason why not. The only requirements are that the AQL test must be carried out in the same rooms as the visual inspection of the batch and that the batch remains in the room during the subsequent AQL testing.