RULES FOR PLANNED REPLACEMENT OF AIRCRAFT AND MISSILE PARTS

The replacement policies are investigated for aircraft and missile parts. The appropriate policy for a part depends on its failure characteristics and the cost of an in-service failure rela ive to the cost of a pla ned replacement. For planned replacement replacement before failure to be worthwhile, the part must display a wear-out characteris ic a failure rate increasing with time and the cost of an in-service failure must be greater than the cost of a planned replacement. The gross savings to be had by following a planned-replacement policy rather than a replacement-at-failure policy are computed for the discrete and for the four continuous distributions. When the relative cost of an in-service failure is large, such s vings can be very significant. Au hor