By Robert A. “Rob” Miller
As described in the earlier segment, Enhanced Reliability Centered Maintenance is a means by which components may be proactively removed prior to failure based upon a statistical analysis of their predicted life cycle. The more time a component has been in use for a certain mission set, the more likely that component will fail within “x” hours. Effectively developed Weibull Analysis and Histogram plots, along with mountains of clean data and serialized tracking of assets are all critical components of big data which separates old-school RCM from the eRCM now used with great effect by such companies as Delta Airlines and is now being rolled into the DoD sustainment infrastructure. Each of these topics are, due to their technical nature, highly encourage as separate activities of study, but outside the scope of this article. What I want to focus on are the initial findings of the C-130 CBM+ eRCM effort, and their eye-opening supportability implications for all logisticians:
1) The level of “Infant Mortality” associated with reparables creating the highest negative impact for supportability was…disturbing. “Infant Mortality” is a term usually utilized in association with new production components. In the sense of a mature platform like the C-130, it refers to components having been recently cycled through a heavy/depot maintenance activity for repair. Items with an advertised A(i) of thousands of hours were only lasting on-wing for 300 or less, while some components seemingly never failed. Although the normal reliability curve dictates failures to mimic this pattern to some degree, the real-world results were far worse than anticipated on an academic plot.
The potential causes of this issue are multiple: Faulty repair components, failure of the “5 T’s” of Maintenance at any level of repair (Time, Tools, Technical Data, Training, Tell if you don’t have them), PHS&T, etc. Each of these root causes is a possibility for each component. The team currently theorizes that due to the age of many reparable components, those components are returned to depot/heavy repair with a range of marginal components, of which only a few (or one) may be addressed during the repair cycle. For example, Navigation Component “A” has one failed and four marginal sub-components inside when returned for repair. The failed sub-component is repaired, while the marginal sub-components remain. The box passes Acceptance Test after repair and makes it back to the field, where one of the remaining sub-components fail after only a few hours of use. The vicious cycle repeats again and again, driving high sustainment cost and, even worse, large amounts of unnecessary, unscheduled maintenance for the operational level maintainers. Lessons learned are twofold: 1) As components age, a change in sustainment philosophy from repair-centric to overhaul-centric will be a vital consideration, 2) There is absolutely no substitute for effective Root Cause Analysis associated with high-failure components. Anything less will drive sub-optimal solutions, high cost, and additional unscheduled maintenance.
2) As night follows the day, the corporate (total supportability vice public/private sector) focus on Ao without concern for MTBMu creates truly awful behavior. We can generate repairs like flapjacks and carry mountains of inventory, but that approach helps neither mission success, nor MTBMu rates—with predictable secondary and tertiary impact. A better focus is “Time on Wing,” supported by the effective Root Cause Analysis mentioned above (it might not be that the actuator needs improving, but rather an associated pump or valve needs a re-design, maintenance practice needs to change, etc.). I’m reminded of the noble young men and women on the flightline at Nellis AFB during a July Red Flag who, while preparing aircraft to launch on an afternoon mission, burn their hands servicing aircraft. Asking those troops to do recreational maintenance is simply unacceptable. Saying “my Ao numbers are good,” or (actually heard during a meeting) “my Inherent Reliability is good, so it’s not my problem” is a mentality that has to change if we are to drive truly effective supportability solutions to our ultimate customers.