What happened
The FAA’s narrative, in sentence case. The FAA writes it in capitals and removes private details.
(-23) The pilot stated that he heard a loud bang and felt a shudder in the airframe shortly after takeoff from an offshore platform. The pilot immediately entered an autorotation with the intent of landing on the water. The pilot was not able to deploy the emergency floats before contacting the water. The aircraft rolled over and became submerged upside down. The pilot and two passengers exited the aircraft without injury. The investigation revealed that the engine compressor had sustained minor foreign object damage (FOD). It could not be determined whether the FOD occurred before the accident or during the impact sequence. The source of the loud bang and shudder is suspected to be a compressor stall. It was also discovered that the emergency float system inflation mechanism was not rigged properly.
As the FAA filed it
(-23) THE PILOT STATED THAT HE HEARD A LOUD BANG AND FELT A SHUDDER IN THE AIRFRAME SHORTLY AFTER TAKEOFF FROM AN OFFSHORE PLATFORM. THE PILOT IMMEDIATELY ENTERED AN AUTOROTATION WITH THE INTENT OF LANDING ON THE WATER. THE PILOT WAS NOT ABLE TO DEPLOY THE EMERGENCY FLOATS BEFORE CONTACTING THE WATER. THE AIRCRAFT ROLLED OVER AND BECAME SUBMERGED UPSIDE DOWN. THE PILOT AND TWO PASSENGERS EXITED THE AIRCRAFT WITHOUT INJURY. THE INVESTIGATION REVEALED THAT THE ENGINE COMPRESSOR HAD SUSTAINED MINOR FOREIGN OBJECT DAMAGE (FOD). IT COULD NOT BE DETERMINED WHETHER THE FOD OCCURRED BEFORE THE ACCIDENT OR DURING THE IMPACT SEQUENCE. THE SOURCE OF THE LOUD BANG AND SHUDDER IS SUSPECTED TO BE A COMPRESSOR STALL. IT WAS ALSO DISCOVERED THAT THE EMERGENCY FLOAT SYSTEM INFLATION MECHANISM WAS NOT RIGGED PROPERLY.
NTSB investigation
The NTSB’s investigation of this event, with its probable cause and findings. Matched to this report by N-number and date.