Jez,
We make our blades at Sikorsky, of three types. The Aluminum blades for the H-3/S-61 and 53, the Titanuim blades for the H-60/S-76 and the Composite blads for the S/H-92 and H-60.
It is Sikorsky's philosophy to design, research and make all the rotating stuff, transmissions, blades heads and the like. It is the essence of the helicopter, and the "family jewels" so to speak. We do farm out gears and of course buy the bearings from the houses that specialize in that stuff (Lord elastomers, for example).
We do not make blades for anyone else's machines.
I know that kaman made blades for Cobras for a while (they gave lots more performance than the older Bell design) and Bell, Boeing Philly and McD/Boeing make their own blades, as far as I know. So does Robinson.
Carson Helicopters just certified a new composite blade for the S-61 which has a new airfoil that significantly improves performance over the old 0012 airfoil on the original blades.