This specification covers the general requirements for nonestablished reliability(non-ER) nd established reliability(ER), lead screw actuated; wire wound variable resistors with a contact bearing uniformly over the surface of the entire resistive element, wound linearly, when positioned by a multiturn lead screw actuator. These resistors are capable of full load operation(when the maximum resistance is engaged), at a maximum temperature of 85?C and are capable for continuous operation, when properly derated, at maximum temperature of 150?C(see 3.6), with a resistance tolerance of ±5 percent. The ER resistors have life failure rate(FR) levels ranging from 1.0 percent to 0.001 percent per 1,000 hours(see 1.2.1.4). These FR levels are established at a 60 percent confidence level on the basis of life tests.