The dear old Sea King has done a tremendous job over the years, but being bounced around at high AUM in crappy weather takes its toll on any airframe, especially an old one. If you then slash spares support you get the level of serviceability now being experienced, despite the best efforts of the engineers.
I know that the Sea King has had its OSD shifted off into the distance and senior officers may well be saying RAF SAR is not for sale... BUT the military role of SAR was essentially a cold war task and doesn't fit into todays expeditionary operations terribly well. There is nothing in the role that could not be done by contract crews flying modern civil aircraft. Things to be gained by this change; new, faster, more capable, more serviceable aircraft: a lot less personnel required to manage and run the operation; no military pensions or salaries to pay.
Most important for MoD is the money saved by taking this approach, they may even be able to shift the whole financial burden across to DoT. I know SAR isn't that expensive compared to eurofighter etc but when you're skint if you can save a few million here or there and the job still gets done. It is all slightly sad but this has been on the cards for a long time. I think that when the MCA contracts come up for renewal there could be some serious changes. Also, unlike the military any civil company could ramp up to take it all over within 18 months to 2 years of contract award and that includes getting aircraft and crews ready.