The original design concept of the EH-101 was to do most of the flying on two engines and bring the third engine on line in case of a power loss on one of the operating engines or when extended hovering was required.
On an unrelated matter, when I was supervising the R&M on the EH-101 I noted to my manager that if the helicopter ever landed on the water and took off again they could suffer power loss due to ingestion of water into the fuel tank. He indicated that the helicopter would only land on water in an emergency and when it did it would be towed to safe refuge and recovered or recovered by its’ mother ship. However I do not believe there ever was a note in the maintenance manuals or operations manual to check the fuel tanks for the presence of water. If the helicopter landed because of a mechanical problem then when it was recovered it would be repaired and returned to service with 10-20 gallons of seawater in the tanks.