MIL-PRF-39035 Resistor, Variable, Nonwirewound \(Adjustment Type\), Nonestablished Reliability, And Established Reliability, General Specification ForThis specification covers the general requirements for nonestablished reliability \(non-ER\) and established reliability \(ER\), multiturn lead-screw actuated, and single-turn, nonwirewound, variable resistors with a contact bearing uniformly over the surface of the entire resistive element, when positioned by an actuator. These resistors are capable of full-load operation \(when the maximum resistance is engaged\), at a maximum temperature of 150 Degrees C, with a resistance tolerance of ??10 percent. The ER resistors will have life failure rate levels ranging from 1.0 to 0.001 percent per 1,000 hours \(see 1.2.1.5\). These failure rate levels are established at a 60 percent confidence level maintained at 10 percent producer\'s risk on the basis of the life tests.

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MIL-PRF-39035E

3.35 Workmanship. Resistors shall be processed in such a manner as to be uniform in quality, and shall be free

from holes, fissures, chip, corrosion, and malformation. The terminals shall be unbroken and not crushed or nicked;

and the resistors shall be free from other defects that will affect life, serviceability, or appearance.

4. VERIFICATION

4.1 Classification of inspections. Inspection requirements specified herein are classified as follows:

Qualification inspection (see 4.4).

Verification of qualification (see 4.5).

Conformance inspection (see 4.6).

Periodic group B inspection (see 4.7).

4.2 Reliability and quality.

4.2.1 QPL system. The manufacturer shall establish and maintain a QPL system in accordance with 3.3.

Evidence of such compliance is a perquisite for qualification and verification of qualification.

4.2.1 SPC system. The SPC program shall be established and maintained in accordance with EIA-557. Evidence

of such compliance shall be a perquisite for qualification and verification of qualification.

4.3 Inspections, conditions and precautions.

4.3.1 Inspection. Unless otherwise specified herein, all inspections shall be performed in accordance with the test

4.3.2 Precautions. Adequate precautions shall be taken during inspection to prevent condensation of moisture on

resistors. Precautions shall also be taken to prevent damage by heat when soldering resistor leads to terminals.

4.4 Qualification inspection. Qualification inspection shall be performed at a laboratory acceptable to the

Government (see 6.3), on sample units produced with equipment and procedures normally used in production.

4.4.1 Sample. The number of sample units comprising a sample of resistors to be submitted for qualification

inspection shall be as specified in appendix A of this specification. The sample shall be taken at random from a

production run and shall be produced with equipment and procedures normally used in production. Each resistor

style shall be qualified separately.

4.4.2 Test routine (see appendix A). Sample units shall be subjected to the qualification inspection specified in

table VII in the order shown. Sample test routine shall be as indicated in appendix A. The qualification of other than

"P" type terminals shall be only applicable at the time of the original submission (see appendix A). The manufacturer

shall not submit all of one terminal type at original submission and request qualification extension to a different

terminal by partial submission at a later date. The qualification life sample shall be continued on test for 10,000

hours. The requirement of A.3.2 in appendix A shall apply for FR data accumulation.

4.4.3 Defectives. Defective specimens in excess of the quantities allowed in table VI shall be cause for refusal to

grant qualification.