Incident Overview
A helicopter conducting a local sightseeing flight over the East River in New York City experienced a sudden loss of engine power. The pilot immediately deployed the emergency floats and initiated an autorotation, successfully landing the aircraft on the river.
Examination Findings
Subsequent examination of the engine revealed that an O-ring was in an improper position on the turbine splined adapter, which connects the turbine and compressor sections. Additionally, the splined end was found to be dry of lubrication and worn to the point of disengagement between the compressor and turbine.
Assembly Process
According to the Federal Aviation Administration (FAA), during engine assembly, the O-ring is installed and checked to ensure it is in the proper position before the engine halves are assembled. However, during assembly, once the O-ring is no longer visible, it could become rolled out of position or damaged. Such misplacement could prevent lubrication from reaching the splined end, leading to the wear and eventual disengagement observed in this incident.