If you are still doing time-based or run-time-based
maintenance (Preventive Maintenance or PM) as a primary maintenance strategy
you should be aware of the "Waddington Effect".
20 years before Nowlan and Heap wrote “Reliability Centered Maintenance”, and way before John Moubray wrote RCM2 was work down by a British
scientist named C.H. Waddington who was put in charge of British aircraft
maintenance in WWII.
He stated that unscheduled downtime should be a random
phenomenon. If all unscheduled downtime
events are plotted with respect to the last PM, there should not be any pattern
evident.
Waddington concluded that the scheduled maintenance: “…tends
to increase breakdowns, and this can only be because it is doing positive harm
by disturbing a relatively satisfactory state of affairs. Secondly, there is no
sign that the rate of breakdown is beginning to increase again after the 40-50
flying hours, when the aircraft is coming due for its next [scheduled
preventive maintenance event].”
In other words the Waddington Effect states that scheduled
preventive maintenance was actually doing more harm than good.
Have you formally tracked unplanned downtime that happens
shortly after a scheduled PM at your company?
If you are not ready for more proactive reliability-based
approaches, one thing you can do is to look at increasing the time or operating
hours between PM's - a pretty simply solution if you are stuck in the Waddington Effect.
No comments:
Post a Comment