On September 15, 2002, about 1445 eastern daylight time, a
Hughes 369A helicopter, N336SP, was substantially damaged during
a forced landing to the Rocky Gorge Reservoir, Burtonsville,
Maryland. The certificated private pilot and passenger received
minor injuries. Visual meteorological conditions prevailed, and
no flight plan was filed for the personal flight conducted under
14 CFR Part 91.  According to the pilot, he had alerted a
mechanic that he had felt a shutter on the previous flight, and
requested that work be performed on the tailrotor assembly
during an upcoming annual inspection. When the pilot examined
the helicopter after the annual inspection was completed on
September 13, 2002, he noticed that the rudder pedals "were a
little stiff." The mechanic balanced the tailrotor, and
subsequently signed the maintenance logs.  On the day of the
accident, the pilot preflighted the helicopter and departed on
the helicopters first flight after the annual inspection. About
a minute after liftoff, the pilot exp