The availability for offshore going 139's is getting over 96% which is fairly good for a helicopter. Would be nice to match the 99%+ that big fixed wing achieve but that is probably a pipe dream.
FIPS is possibly dragging this figure down for operators with the system but with comments along the lines that "maintenance is just maintenance" I would suggest that there are other issues as well.
Pilots like the 139 as do engineers. Like all helicopters it has it's moments but AW continue to improove the product and I think the sales speak for themselves.
One comment I have heard from a friend working on a single aircraft operation is that it breaks down so infrequently now that fault finding experience is hard to come by.