Southbound has summated matters very well. Whilst the current definition may have changed to Lean / Pulse, below ifrom whence the concept(s) originated.
Like any theory, it holds great appeal until the point of implementation that is. A very large airline tried this a few years ago, with much heralding of trumpets of course--only for the concept to be quietly dropped albeit with a few token chamges introduced. As far as I am aware, it's never been a success within a maintenance environment due to the variables involved as mentioned by another poster here. Then there is the more pervasive matter of "change management" to consider of course. The "holy grail" of management consultants and beancounters and a very dark area to boot. Possibly not quite as difficult to implement in the military because those little pieces of documentation called QR's / The Air Forc Act etc. Unlike the civilian world where resistance can be nullified, but usually at a greater cost to an organisation than would be wished for in terms of manpower and expediture.
Lots of info below for those who are interested enough to get an idea as to what's involved and the pitfalls that await. More on Google of course.
http://www.lmu.ac.uk/lis/imgtserv/tools/BPR.htm