Accident
A Bell 206B helicopter was conducting a sightseeing flight around the island of Manhattan when it encountered a low rotor rpm situation. The pilot reported being unable to recover rotor rpm and executed a forced landing in the East River.
Following the landing, the pilot and three passengers exited the aircraft and clung to the floats, which had inflated and then separated from the helicopter. One passenger did not escape and was found inside the aircraft approximately one and a half hours later; that passenger died of drowning.
Investigation
Investigators found a fatigue crack on the power turbine governor near the PY port. The crack would cause the engine to lose power. The low rotor rpm warning horn sounded throughout the descent, as designed. No evidence of any collective control problem was found, and the pilot did not mention a jammed collective.
Probable Cause
The National Transportation Safety Board determined the probable cause to be a fatigue crack on the power turbine governor near the PY port, which caused the engine to lose power, leading to a low rotor rpm condition and subsequent forced landing.