MIL-STD-690 Failure Rate Sampling Plans And ProceduresThis standard provides procedures for failure rate FR qualification, sampling plans for establishing and maintaining FR levels at selected confidence levels, and lot conformance inspection procedures associated with FR testing for the purpose of direct reference in appropriate military electronic parts established reliability ER specifications. Figures and tables throughout this standard are based on exponential distribution. Weibull distribution will be acceptable in certain components such as capacitors. Use of Weibull distribution for any component must be approved by the qualifying activity. This standard also provides guidance to specification writers in the use of this standard see appendix A and references material for users of ER parts.

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	MIL-STD-690D w/ CHANGE 1
	CONTENTS
PARAGRAPH		PAGE
5.3.4	Sublotting failure rate maintenance procedure, failure rates R and S (optional)	17
5.3.4.1	Failure to meet overall "C" number	18
5.3.4.2	Overall "C" number not exceeded	18
5.3.4.3	Example of sublot calculation	18
5.3.5	Details to be specified	18
5.4	Procedure IV, Lot conformance FR inspection"	19
5.4.1	Sampling plans	19
5.4.2	Extended FR tests	19
5.4.3	Action in case of failure	19
5.4.4	Details to be specified	20
5.5	Procedure for truncation of life test data	20
6.	NOTES	21
6.1	FR level conversion	21
6.2	Computation of the unit-hour requirement	21
6.3	Computation of the true failure rate	21
6.4	Subject term (key word) listing	21
6.5	Changes from previous issue	22

APPENDIX A

A.1	SCOPE	28
A.1.1	Scope	28
A.2	APPLICABLE DOCUMENTS	28
A.2.1	General	28
A.2.2	Government documents	28
A.2.2.1	Specifications, standards, and handbooks	28
A.2.3	Order of precedence	28
A.3	QUALIFICATION	28
A.3.1	Qualification at the initial FR level	28
A.3.2	Extension of qualification to lower FR levels	28
A.3.3	Maintenance of FR level qualification	29
A.3.4	Verification of qualification	29
A.4	LOT CONFORMANCE FR INSPECTION (WHEN SPECIFIED)	29
A.4.1	Sampling plan	29
A.5	GENERAL	29
A.5.1	Failure criteria	29
A.5.2	Duration of failure rate test	30
A.5.3	Screening tests	30
A.5.4	Accelerated FR tests and acceleration factors	30
A.6	FR QUALIFICATION DATA	30
A.6.1	Expanding FR sampling plan	30
A.7	APPLICATION INFORMATION	30
A.7.1	Reliability data	30