DOLPHIN EATS SNOW!

In December, 1983, Aerospatiale Helicopter Corporation (AHC) was tasked by one of our customers, the U.S. Coast Guard, with solving an engine surge problem which was occurring during flight in snow. An intensive program during the following 16 months resulted in a satisfactory solution. During this time, the problem was defined, success criteria established, and numerous candidate fixes evaluated. Tests were conducted in Texas, France, Stratford Connecticut, Ottawa, Eglin AFB Florida, England, and in snowstorms across the northern U.S. The field was narrowed to two candidate fixes; an Engine Plenum Inlet which added a plenum chamber at the inlet of a modified engine, and an Alternate Air Inlet which took air from the main rotor gearbox compartment during snow operation. After all factors were considered, the Plenum Inlet was selected, and successfully completed snow certification testing on 1 April 1985. AHC believes that the success criteria per FAA Advisory Circular 29-2 Change 2 is inordinately severe and hazardous to demonstrate due to the requirement for sustained hover in "whiteout" conditions. Also. since the required atmospheric conditions are extremely rare in nature, a means should be found for crediting tests conducted with artificially produced snow.