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MIL-PRF-22 Resistors, Variable, Wirewound, Power Type, General Specification ForThis specification covers the general requirements for power type variable resistors having a resistance element of wire, wound linear on an insulating strip shaped in an arc, such that a contact bears uniformly on the resistance element when adjusted by a control shaft. The power ratings \(see 3.1\) cover a range from 6.25 watts to 1,000 watts, inclusive \(see 6.2\).

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MIL-PRF-22E

4.5 Retention of qualification. Every 12 months, the manufacturer shall verify the retention of qualification to the

qualifying activity. In addition, the manufacturer shall immediately notify the qualifying activity whenever the group B

inspection results indicate failures of the qualified product to meet the requirements of this specification. Verification

shall be based on meeting the following requirements:

The manufacturer has not modified the design of the item.

The specification requirements for the item have not been amended so far as to affect the character of the

item.

Lot rejection for group A inspection does not exceed the group A sampling plan.

The requirements for group B inspection are met.

When group B requirements were not met and the manufacturer has taken corrective action satisfactory to the

Government, group B inspection retesting shall be instituted. A summary of the retesting shall be forwarded to the

qualifying activity within 30 days after completion of the retest. All reports are to be certified by a responsible

company official and the government inspector.

TABLE IV. Qualification inspection for standard bushing models.

Requirement

Method

Number of

Number of failures

Examination or test

Paragraph

samples

allowed 1/

Group I 2/

Visual and mechanical examination 3/

3.1, 3.3 to 3.4.5,

3.4.6 to 3.4.9.2 inclusive,

4.7.1

3.18 to 3.21 inclusive

Dielectric withstanding voltage

3.5

4.7.2 to 4.7.2.2,

inclusive

DC resistance

3.6

4.7.3 to 4.7.3.2,

inclusive

Torque

3.7

4.7.4 to 4.7.4.3,

inclusive

Low temperature exposure

3.8

4.7.5

Group II

Power rating (when applicable)

3.9

4.7.6 to 4.7.6.2

inclusive

Load life

3.10

4.7.7

Vibration (low frequency) 4/

3.11

4.7.8

Salt spray (corrosion)

3.12

4.7.9

Group III

Humidity (steady state)

3.13

4.7.10

Group IV

Rotational load life

Terminal strength

Shock (specified pulse) 4/

3.16

4.7.13

Group V 5/

Acceleration

3.17

4.7.14 to 4.7.14.4

inclusive

Shock (specified pulse)

3.16

4.7.13

Vibration (high frequency)

3.18

4.7.15

Group VI

Fungus

3.3.1

4.7.16

Failure of a resistor in one or more tests of a group shall be charged as a single defective.

Nondestructive examination and tests.

Marking shall be considered defective only if marking is illegible.

Not applicable to styles RP05, RP06, and RP07 (see 3.1).

Applicable only to RP05, RP06, and RP07 (see 3.1).