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8.1 Limitation to Approved Quality Control Plans. Approval holders may perform additional
testing and
inspection not listed in their approved quality control plans. Sampling for these
additional inspections is
not required to meet the requirements set forth in 42 CFR Part 84 and this
letter. However, there must
be a reasonable basis for selecting the sampling plans used.
8.2 Limitation to Required Testing. In some cases, applicants may wish to list testing and
inspection in their
quality control plans above that required by NIOSH for effective quality
control of respirator performance.
Sampling done for these additional inspections is not required
to meet the requirements in 42 CFR Part 84
and this letter. Additional testing should be identified
clearly, such as with the notation “additional
inspection,” on documents submitted with the
application to avoid delay and requests for clarification
during processing. Any such testing
listed in the approved quality control plan must be conducted as
required by 42 CFR Section 84.42(c).
9. Common Errors
9.1 Selection of Inadequate Inspection Levels. The minimum acceptable inspection level is
described in
section 3.2 of this letter. If a product quality control plan does not specify
inspection levels, NIOSH assumes
that the level in the “normal” column of the table will be
used. Use of lower levels without specific
approval, whatever the reason, is a failure to conform
to NIOSH requirements and can result in revocation of
approval under 42 CFR Section 84.43(c).
9.2 Selection of Plan Based on Desired Sample Size. It is entirely improper to choose a desired
sample size
and work backwards to identify a proposed AQL and inspection level which will
yield this result. To do so
reflects a fundamental misunderstanding of the basis for sampling
plans. The appropriate AQL and
inspection level are stated in sections 2.2 and 3.2 of this letter.
9.3 Selection of Defect Classification Based on Desired AQL. As in 9.2, the defect classification
drives the
selection of AQL, not the other way around. Each defect must be classified based
solely on the definitions in
42 CFR Section 84.41(d).
9.4 Modification of AQL or Inspection Level Based on Lot Size or Other Factors. The AQL and
inspection level
are chosen by the criteria in sections 2.2 and 3.2 of this letter. Approval holders
are free to use higher
inspection levels if greater discrimination is desired, or to use lower (more
stringent) AQLs if a smaller
percent defective is desired. However, these should not be modified
based on lot size or inspection history,
as provisions already exist to account for those factors.
Changing AQL values or inspection levels is likely to
result in a statistically invalid plan.
9.5 Inappropriate Use of Reduced Inspection. As described in section 4.1 of this letter, reduced
inspection is
permitted only when all conditions of the relevant procedure are met. When there
are significant delays or
changes in production processes, approval holders must revert to normal
inspection. It will be considered a
nonconformance during NIOSH on-site audits if the records
described in section 4.2 of this letter are not
available.
9.6 Incorrect Sample Size When Following Arrows in Sampling Tables. When using attribute
sampling, be
careful when following arrows in the sampling plan tables. A different sample size
must be used to
correspond with the new code letter as described in section 6.1 of this letter.