What happened
The FAA’s narrative, in sentence case. The FAA writes it in capitals and removes private details.
On an approximately 1 mile final, at 500'-600' AGL, pilot performed pre-landing checks and noticed abnormally high oil pressure reading. Oil pressure gauge needle was "pegged" beyond the red line. Stated oil temp gauge was higher than normal but at top of the green arc.
Shortly after, pilot noticed RPM decay (2800-2900 RPM) below the green arc. (Helicopter not equipped with low RPM warning system.) Pilot responded by adding throttle but noticed no change in RPM. Engine and rotor RPM continued to decay. Pilot entered autorotation by rolling throttle off and lowering collective. In attempt to complete ditching procedure, aircraft made hard contact with water.
The pilot and passenger egressed helicopter. The aircraft sank immediately (lake is 400' deep). The pilot and passenger swam towards shore and were picked up by a neighbor in a boat.
As the FAA filed it
ON AN APPROXIMATELY 1 MILE FINAL, AT 500'-600' AGL, PILOT PERFORMED PRE-LANDING CHECKS AND NOTICED ABNORMALLY HIGH OIL PRESSURE READING. OIL PRESSURE GAUGE NEEDLE WAS "PEGGED" BEYOND THE RED LINE. STATED OIL TEMP GAUGE WAS HIGHER THAN NORMAL BUT AT TOP OF THE GREEN ARC.
SHORTLY AFTER, PILOT NOTICED RPM DECAY (2800-2900 RPM) BELOW THE GREEN ARC. (HELICOPTER NOT EQUIPPED WITH LOW RPM WARNING SYSTEM.) PILOT RESPONDED BY ADDING THROTTLE BUT NOTICED NO CHANGE IN RPM. ENGINE AND ROTOR RPM CONTINUED TO DECAY. PILOT ENTERED AUTOROTATION BY ROLLING THROTTLE OFF AND LOWERING COLLECTIVE. IN ATTEMPT TO COMPLETE DITCHING PROCEDURE, AIRCRAFT MADE HARD CONTACT WITH WATER.
THE PILOT AND PASSENGER EGRESSED HELICOPTER. THE AIRCRAFT SANK IMMEDIATELY (LAKE IS 400' DEEP). THE PILOT AND PASSENGER SWAM TOWARDS SHORE AND WERE PICKED UP BY A NEIGHBOR IN A BOAT.
NTSB investigation
The NTSB’s investigation of this event, with its probable cause and findings. Matched to this report by N-number and date.