MIL-DTL-62542C
Failures are defined as malfunctions or incidents that prevent the BSLA from successfully
completing a mission essential function (see 3.3.6) or as otherwise identified in 4.7.2.2
(see 4.7.2.3).
4.7.2.2 Operational reliability failure (ORF). An ORF is any malfunction that prevents
further operation of a major BLSA component and requires that the component must be replaced
or repaired. The major components are the motor, drivetrain, screw, housing, rod end bearing,
and ball return assembly. An ORF is also any incident or malfunction (actual, intermittent, or
incident) of the BSLA system which causes or could have caused the inability to perform one or
more mission essential functions, or is a critical or catastrophic hazard to personnel or equipment.
4.7.2.3 Maintainability verification. Failure occurs when the total maintenance manhours
expended to perform active scheduled and unscheduled maintenance per BSLA exceeds one
manhour or when safety hazards to personnel/unsafe conditions develop that require corrective
(unscheduled) maintenance action.
4.7.3 Ball screw. The BSLA shall be fully extended and then retracted. The backlash
shall be determined in each position.
4.7.3.1 Ball screw scoring. The test specified in 4.7.1 shall be completed. Subsequently,
the entire length of the ball screw shall be checked for any evidence of scoring using
10X magnification inspection.
4.7.4 Manual override. The BSLA shall be extended and retracted one time and checked
for smooth operation using a standard English size socket wrench which may be attached to a drill
motor.
4.7.5 Water exclusion. Water seal test shall be performed after completion of the
reliability test. The test shall be performed with the BSLA screw extended (exposed) 20 in. from
the rod end of the ball screw actuator. The BSLA shall be placed in a vertical position with the
rod end pointing up with all casting vents, lubrication fittings, plugs and access holes in a closed
position. The BSLA shall be subjected to a constant flow of water running down the screw at a
rate of one gallon per hour for a three hour period. Accumulation of water inside the ball screw
actuator assembly in excess of two ounces is unacceptable. Water accumulation shall be
determined by water extracted from the actuator by removing plugged holes from the chamber
and disassembly of the BSLA.
4.7.6 Actuator lubricant. The zero lubricant leakage shall be verified in conjunction with
the evaluation of the BSLA's reliability (see 4.7.2).
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