It will prevent the need for HMG to stump up a really major amount to recapitalise the helicopter fleet by buying new aircraft.
It won't save money over the long term, like all these PFIs and PPPs. You save big blobs of capital investment and pay more in lease costs, including profits for the provider.
And you end up dumping a gold standard, 'money no object' based military service for a lowest cost, lowest bidder commercial one.