TC, I realize the HV chart for a twin is only for one engine out. My statement was that the chart was in the Limitations Section rather than the performance section.
Jim, Thanks for your notes. As for containment rings, I have mixed feeling about them. I have a good friend that had an engine come apart on a S76A. It had the containment ring and the other engine failed soon after. Pieces from the 1st engine FOD'd the 2nd engine. What I heard about the investigation was that at least one piece of first engine entered the second engine and was fed further into the engine causing more damage and the failure of the second engine.
Many years ago, an acquaintance of mine was flying a Beech 99 for a commuter airline. One of the engines came apart and one of the turbine blades entered the cockpit and cut his leg off. The blade was hot enough to cauterize the wound. The aircraft did not have a containment ring. While this sounds bad, it could have been worst. There were discussions between the FAA, NTSB, Beechcraft, PWC and the operator that indicated that if the containment ring was in place, the situation could very possibly been worst. What I was told by my acquaintance was that the piece could have very possibly entered his head or chest cavity. It would have been deflected and reshaped in some manner. Even if it hit his leg at the same spot, the change in velocity and angle could have caused a larger wound and he could have bled to death rather quickly.
And Jim I agree with your comment about engine capacity being a reason for twin engine helicopters. But keep in mind the 214B, it has one BIG engine. Two smaller engines are most likely much less expensive than one BIG engine.