MIL-PRF-39005 Resistors, Fixed, Wirewound \(Accurate\), Nonestablished Reliability, Established Reliability, General Specification ForThis specification covers the general requirements for nonestablished reliability \(non-ER\), established reliability \(ER\), accurate, wire-wound, fixed resistors that have a maximum resistance tolerance of 1 percent and a high degree of stability with respect to time under specified environmental conditions. The resistors are capable for continuous full-load \(or voltage\) operation at any ambient temperature up to 125??C, and when derated, up to 145??C \(see 6.5\). They are not capable for application where the alternating current \(ac\) characteristics are of critical importance. ER resistors have life failure rates \(FR\) ranging from 1.0 percent to 0.001 percent per 1,000 hours \(see 1.2.1.5\). These FR are established at 60-percent confidence level on the basis of the life tests. The FR, identified by the appropriate symbol, is referred to operation at full rated voltage and temperature.

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MIL-PRF-39005G

4.6.5 Group B inspection. Group B inspection shall consist of the inspections specified in table XIII, in

the order shown, and shall be made on samples from lots which have been subjected to and passed the

group A inspection. Sample units selected for subgroup 1 shall be of the highest resistance value;

subgroup 2 sample units shall be of any value.

4.6.5.1 Sampling plan.

4.6.5.1.1 Subgroup 1. A sample of 13 parts (highest value) shall then be randomly selected. If one or

more defects are found, the lot shall be rescreened and defects removed. If one or more defects are

found, a new sample of 13 parts (highest value) shall then be randomly selected. If one or more defects

are found in the second sample, the lot shall be rejected and shall not be supplied to this specification.

TABLE XIII. Group B inspection (ER only).

Inspection

Requirement

Test method

Number of

Number

paragraph

samples

of failures

Subgroup 1 1/

(highest value)

Resistance temperature characteristic

3.18

4.8.14

Subgroup 2 1/

12 (any value)

Resistance to solvents

3.23

4.8.19

4.6.5.1.2

1/ If the manufacturer can demonstrate that this test has been performed five consecutive times with

zero failures, the frequency of this test, with the approval of the qualifying activity, can be performed

on an annual basis. If the design, material, construction, or processing of the part is changed, or if

there are any quality problems or failures, the qualifying activity may require resumption of the

original test frequency.

4.6.5.1.2 Subgroup 2. A sample of 12 parts (any value) shall then be randomly selected. If one or

more defects are found, the lot shall be rescreened and defects removed. If one or more defects are

found, a new sample of 12 parts (any value) shall then be randomly be selected. If one or more defects

are found in the second sample, the lot shall be rejected and shall not be supplied to this specification.

4.6.5.1.3 Disposition of sample units. Sample units which have been subjected to group B inspection

may be delivered on the contract provided they are within resistance tolerance and meet requirements for

visual and mechanical inspection.

4.7 Periodic group C inspection (ER only). Periodic inspection shall consist of group C inspection,

except where the results of these inspections show noncompliance with the applicable requirements (see

4.7.6), delivery of products which have passed group A and group B shall not be delayed pending the

results of the periodic inspections.

4.7.1 Group C inspection (ER only). Group C inspection shall consist of the inspections specified in

table XIV, in the order shown. Group C inspection shall be made on sample units selected from

inspection lots which have passed the group A and group B inspections.