The helicopter pilot stated that he was conducting an aerial application flight before landing due to deteriorating weather. After landing on a wet, elevated platform, he exited the running helicopter, which was a common company practice during refueling and reloading operations. Moments later, the helicopter yawed to the right, slid off the platform and landed on the mast, resulting in substantial damage to the rotor assembly, left side fuselage, and tail boom. The pilot later stated that he did not recall securing the flight controls before exiting the helicopter. A Federal Aviation Administration examination of the accident scene revealed that the flight control friction locks were not tight, and that the landing platform was not level. A representative of the helicopter manufacturer stated that there was nothing published by the company that restricted a pilot from exiting a helicopter while it was running. However, there is a note in the pilot’s operating handbook for the engine shutdown procedure that states, “Pilot -- remain at flight controls until rotor has come to a complete stop.” A representative of the National Agricultural Aviation Association stated that although the practice of hot refueling was common in the industry, the practice of exiting a running helicopter was not.