I hate to yet again be the gadfly to put pins in Lu's credibility, but on water operations in helicopters is very normal, very natural and very safe. Rotor starts, takeoffs and landings are normal water operations for many helicopters, and gyroscopic precession problems are a mythological problem, like glowing helicopters and 18 degree rigging problems. I have many water landings in boat-hulled helos, and know of lots of normal water-borne operations in many types.
Regarding the original question from Helieng, the several posters who said emergencies only are correct, at least for the Sikorsky S-76 and S-92. They are designed to let folks egress safely, and any more float time is for bragging rights.
Those floats that allow normal operations are so stated in the flight manual as allowing amphibious operations in Chapter 1 of the manual. I know of no pop-out floats that allow amphibious operations.
