What happened
The FAA’s narrative, in sentence case. The FAA writes it in capitals and removes private details.
(-23) The instructor was demonstrating 180 degree autorotations. On a north heading at Nephi airport at 700 AGL the power was reduced to idle. At 200 AGL the instructor pilot did a final check. The RPM was 104% at 1400 fpm descent and at 68 KTS. At 100FT the pilot said that the rate of descent increased and he flared to stop the rate of descent to no effect. He then added full power and pushed cyclic forward. He hit the ground hard spreading the landing gear skids horizontally. The main rotor severed the tail boom from the helicopter. The aircraft came to rest just off to the east of the runway pointing south. From first impact on the west side of runway it traveled diagonally across the runway about 80 yds. Various parts of the helicopter were scattered along the path. There were only minor injuries to the student and none to the pilot. Referred to the operations section.
As the FAA filed it
(-23) THE INSTRUCTOR WAS DEMONSTRATING 180 DEGREE AUTOROTATIONS. ON A NORTH HEADING AT NEPHI AIRPORT AT 700 AGL THE POWER WAS REDUCED TO IDLE. AT 200 AGL THE INSTRUCTOR PILOT DID A FINAL CHECK. THE RPM WAS 104% AT 1400 FPM DESCENT AND AT 68 KTS. AT 100FT THE PILOT SAID THAT THE RATE OF DESCENT INCREASED AND HE FLARED TO STOP THE RATE OF DESCENT TO NO EFFECT. HE THEN ADDED FULL POWER AND PUSHED CYCLIC FORWARD. HE HIT THE GROUND HARD SPREADING THE LANDING GEAR SKIDS HORIZONTALLY. THE MAIN ROTOR SEVERED THE TAIL BOOM FROM THE HELICOPTER. THE AIRCRAFT CAME TO REST JUST OFF TO THE EAST OF THE RUNWAY POINTING SOUTH. FROM FIRST IMPACT ON THE WEST SIDE OF RUNWAY IT TRAVELED DIAGONALLY ACROSS THE RUNWAY ABOUT 80 YDS. VARIOUS PARTS OF THE HELICOPTER WERE SCATTERED ALONG THE PATH. THERE WERE ONLY MINOR INJURIES TO THE STUDENT AND NONE TO THE PILOT. REFERRED TO THE OPERATIONS SECTION.
NTSB investigation
The NTSB’s investigation of this event, with its probable cause and findings. Matched to this report by N-number and date.