This appendix discusses two additional elements of productivity and scheduling, namely wrench time in exceptional crafts and plants and blanket work orders in any plant. The Maintenance Planning and Scheduling Handbook addresses these topics in this appendix so as not to distract from the main thrust of the book.

First, wrench time may be higher than the industry norm of 25 to 35% in some maintenance organizations without highly developed planning functions. The preceding two appendices showed two such examples. In App. G, the I&C (instrument and controls) group had a 38% wrench time. This I&C group did not have a planning function assisting it. The industry norm more applies to an overall maintenance force than to a specific craft. I&C and electrical crafts without planning typically should be at the top or slightly over industry norm. These groups are typically not at the desired 55% level, but their existing productivity may warrant placing them behind the mechanical group in priority for implementation of planning. In addition, in plants where I&C and electrical groups mostly support the mechanical groups, the improvement of the mechanical group's wrench time through planning improves these other crafts as well. Appendix H shows a mechanical group with a marginal planning effort. With only planning, but no weekly scheduling, the craft is at the top of the industry norm for wrench time. Certain crafts, most notably machinists, achieve 50% wrench time due to the nature of their close-at-hand work assignments.

Another situation, not...