What happened
The FAA’s narrative, in sentence case. The FAA writes it in capitals and removes private details.
At approximately 1027 MST at Earnest a. Love field (kprc), the certified flight instructor and student pilot had been on duty approximately three and one half hours before the accident. The pilots stated they were performing their first traffic pattern at prc after takeoff culminating in a 180˚ autorotation. The maneuver began on the downwind leg at approximately 700 feet above ground level (AGL) and 75 knots airspeed. The student pilot began the maneuver by reducing collective pitch to the bottom stop and then raising collective to arrest the main rotor RPM as it built to the correct upper autorotative limit. Simultaneously, the student reduced engine RPM to approximately 92% and initiated a descending right turn to align the aircraft with runway 21 right for a power recovery termination. At approximately 400 feet AGL, both pilots felt a rapid increase in the rate of descent followed by a decrease in rotor RPM to approximately 92%. The flight instructor announced he was taking the controls while pushing the collective down and pulling aft cyclic to rebuild rotor RPM while at the same time, the student pilot pulled up on the collective. The flight instructor again announced that he had the controls, and the student released them. The instructor stated the rotor RPM had decayed to approximately 85%, and he elected to maneuver the helicopter toward the sod area where the helicopter impacted on a track approximately 20˚ left of the runway.
The 0953 MST weather observation at prc indicated scattered clouds at 3000 feet with towering cumulus, 10 miles visibility, winds from 140 degrees at 3 knots with no gusts. The temperature was 24 degrees celsius, dew point was 18 degrees celsius, and the altimeter setting was 30.26 in hg, resulting in a density altitude of approximately 7158 feet. The helicopter impacted the sod upright with enough downward force to buckle the skid strut tubes, causing the tail rotor to strike the ground 3 times and to cause a main rotor blade to flex down to strike, cut off and sling away the tail boom. The following main rotor blade flexed down to strike the ground at the 8 o?clock position causing the helicopter to rotate right and flip over coming to rest on its right side facing approximately east. Both pilots sustained serious injuries. There were no mechanical irregularities reported by the pilots or discovered post-accident.
As the FAA filed it
AT APPROXIMATELY 1027 MST AT EARNEST A. LOVE FIELD (KPRC), THE CERTIFIED FLIGHT INSTRUCTOR AND STUDENT PILOT HAD BEEN ON DUTY APPROXIMATELY THREE AND ONE HALF HOURS BEFORE THE ACCIDENT. THE PILOTS STATED THEY WERE PERFORMING THEIR FIRST TRAFFIC PATTERN AT PRC AFTER TAKEOFF CULMINATING IN A 180˚ AUTOROTATION. THE MANEUVER BEGAN ON THE DOWNWIND LEG AT APPROXIMATELY 700 FEET ABOVE GROUND LEVEL (AGL) AND 75 KNOTS AIRSPEED. THE STUDENT PILOT BEGAN THE MANEUVER BY REDUCING COLLECTIVE PITCH TO THE BOTTOM STOP AND THEN RAISING COLLECTIVE TO ARREST THE MAIN ROTOR RPM AS IT BUILT TO THE CORRECT UPPER AUTOROTATIVE LIMIT. SIMULTANEOUSLY, THE STUDENT REDUCED ENGINE RPM TO APPROXIMATELY 92% AND INITIATED A DESCENDING RIGHT TURN TO ALIGN THE AIRCRAFT WITH RUNWAY 21 RIGHT FOR A POWER RECOVERY TERMINATION. AT APPROXIMATELY 400 FEET AGL, BOTH PILOTS FELT A RAPID INCREASE IN THE RATE OF DESCENT FOLLOWED BY A DECREASE IN ROTOR RPM TO APPROXIMATELY 92%. THE FLIGHT INSTRUCTOR ANNOUNCED HE WAS TAKING THE CONTROLS WHILE PUSHING THE COLLECTIVE DOWN AND PULLING AFT CYCLIC TO REBUILD ROTOR RPM WHILE AT THE SAME TIME, THE STUDENT PILOT PULLED UP ON THE COLLECTIVE. THE FLIGHT INSTRUCTOR AGAIN ANNOUNCED THAT HE HAD THE CONTROLS, AND THE STUDENT RELEASED THEM. THE INSTRUCTOR STATED THE ROTOR RPM HAD DECAYED TO APPROXIMATELY 85%, AND HE ELECTED TO MANEUVER THE HELICOPTER TOWARD THE SOD AREA WHERE THE HELICOPTER IMPACTED ON A TRACK APPROXIMATELY 20˚ LEFT OF THE RUNWAY.
THE 0953 MST WEATHER OBSERVATION AT PRC INDICATED SCATTERED CLOUDS AT 3000 FEET WITH TOWERING CUMULUS, 10 MILES VISIBILITY, WINDS FROM 140 DEGREES AT 3 KNOTS WITH NO GUSTS. THE TEMPERATURE WAS 24 DEGREES CELSIUS, DEW POINT WAS 18 DEGREES CELSIUS, AND THE ALTIMETER SETTING WAS 30.26 IN HG, RESULTING IN A DENSITY ALTITUDE OF APPROXIMATELY 7158 FEET. THE HELICOPTER IMPACTED THE SOD UPRIGHT WITH ENOUGH DOWNWARD FORCE TO BUCKLE THE SKID STRUT TUBES, CAUSING THE TAIL ROTOR TO STRIKE THE GROUND 3 TIMES AND TO CAUSE A MAIN ROTOR BLADE TO FLEX DOWN TO STRIKE, CUT OFF AND SLING AWAY THE TAIL BOOM. THE FOLLOWING MAIN ROTOR BLADE FLEXED DOWN TO STRIKE THE GROUND AT THE 8 O?CLOCK POSITION CAUSING THE HELICOPTER TO ROTATE RIGHT AND FLIP OVER COMING TO REST ON ITS RIGHT SIDE FACING APPROXIMATELY EAST. BOTH PILOTS SUSTAINED SERIOUS INJURIES. THERE WERE NO MECHANICAL IRREGULARITIES REPORTED BY THE PILOTS OR DISCOVERED POST-ACCIDENT.
NTSB investigation
The NTSB’s investigation of this event, with its probable cause and findings. Matched to this report by N-number and date.