MIL-STD-690D
w/ CHANGE 1
APPENDIX A
A.3.3 Maintenance of FR level qualification. Maintenance of FR level qualification shall be monitored by means of a sampling plan based on a 10 percent confidence level. The sampling plan should provide the necessary number of cumulative unit hours (excluding permitted failures) required over a specified time period to maintain the qualified FR level.
A.3.4 Verification of qualification. Every 6 months the manufacturer shall compile a summary of the results of conformance inspection and extended FR test data, in the form of a verification of qualification report, and forward it to the qualifying activity within 30 days after the end of the reporting period as the basis of continued qualification
approval. In addition, the manufacturer shall immediately notify the qualifying activity whenever the FR data indicates that the manufacturer has failed to maintain the qualified FR level or the periodic inspection data indicates failure of the qualified product to meet the requirements of the specification. Continuation of qualification approval shall be
based on evidence that over the 6 month period, the following has been met:
a. The manufacturer meets the requirements of MIL-STD-790. b. The manufacturer has not modified the design of the item.
c. The specification requirements for the item have not been amended so as to affect the character of the item.
d. Lot rejection under the applicable inspection groups does not exceed the specified percentage or one lot, whichever is greater (see 5.3).
e. Requirements for periodic tests are met, if applicable.
* f. The records of FR tests substantiate that the "L" (specified percentage), "M" (1.0%), or "P" (0.1%) FR level has been maintained or that the manufacturer continues to meet the "R" or "U" (0.01%) or "S" or "V" (see
4.1a) (0.001%) FR level for which qualified although the total component hours testing does not as yet
meets the requirements of 5.3.
When periodic requirements were not met and the manufacturer has taken corrective action satisfactory to the Government, periodic retesting shall be instituted. A summary of the retesting shall be forwarded to the qualifying activity within 30 days after completion of the retest.
A.4. LOT CONFORMANCE FR INSPECTIONS (WHEN SPECIFIED)
A.4.1 Sampling plan. When lot conformance FR inspection is considered necessary, the sampling plans of table VI, provided herein, should be used. They provide reasonable assurance of lot quality and that the lot under inspection is not significantly different from previously accepted lots. In view of the fact that in most ER specifications, 100 percent of the product will have been subjected to burn-in/screening tests which are designed to
eliminate early life failures, the need for lot conformance FR tests should be carefully considered. The effect of these lot-by lot tests on the price and delay in delivery of ER parts should be evaluated against the additional verification
information to be gained.
A.5. GENERAL
A.5.1 Failure criteria. The failure criteria for the relatively "short-time" FR test used for lot conformance inspection may differ from the failure criteria established for the extended FR test. The data resulting from the lot conformance FR inspection test, therefore should be analyzed in two ways for the two different purposes it will be used. First, for purposes of lot conformance FR inspection, the failure criteria established for the "short-time" FR test would be applied. Secondly, for purposes of adding to the FR test data being accumulated for FR determinations, the failure criteria established for the extended FR test would be applied to determine whether a failure occurred with these criteria. Therefore, a failure in the lot conformance FR inspection test may not necessary constitute a failure when the unit hours are recorded for the FR determinations. This is necessarily since, for FR determination, the failure criteria should be the same for all data used. For FR determination a single failure criteria should be specified for all measurements.
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