What happened
The FAA’s narrative, in sentence case. The FAA writes it in capitals and removes private details.
(.19)On December 11, 1998, at 1645 hours pacific standard time, a Bell 47G2, N9021R, sustained substantial damage during a forced landing near Helendale, California, following the onset of an airframe vibration. The student pilot, the sole occupant, was not injured. The personal flight originated at cramers junction, California, at 1630, and was en route to Helendale. Visual meteorological conditions prevailed and no flight plan was filed. The pilot reported that he was flying at 200 feet AGL when he felt the helicopter begin to shake. As he reduced the power, the helicopter stopped shaking. The pilot autorotated and landed in an area of hilly and uneven terrain. The tail rotor blades impacted an embankment and the main rotor blades severed the tailboom. (.4) the pilot encountered retreating blade stall while flying at 100 mph. He reported that the helicopter began to shake and it felt like an 'out of balance feeling, like when the washing machine gets unbalanced.' The rotor RPM began to decay. When he reduced power and stabilized the airspeed about 60 to 65 mph, the shaking stopped. The pilot stated that he was not able to maintain lift, so he entered an autorotation ov er the hilly terrain. The tail rotor blades impacted an embankment and the main rotor blades severed the tail boom. The pilot's manual for the Bell 47G2 indicates that the 'never-exceed speed' (vne) for the helicopter is 100 mph. According to the faa's basic helicopter handbook, the recovery procedure for retreating blade stall is to reduce the collective pitch, increase rotor RPM, reduce forward airspeed, and minimize maneuvering.
As the FAA filed it
(.19)ON DECEMBER 11, 1998, AT 1645 HOURS PACIFIC STANDARD TIME, A BELL 47G2, N9021R, SUSTAINED SUBSTANTIAL DAMAGE DURING A FORCED LANDING NEAR HELENDALE, CALIFORNIA, FOLLOWING THE ONSET OF AN AIRFRAME VIBRATION. THE STUDENT PILOT, THE SOLE OCCUPANT, WAS NOT INJURED. THE PERSONAL FLIGHT ORIGINATED AT CRAMERS JUNCTION, CALIFORNIA, AT 1630, AND WAS EN ROUTE TO HELENDALE. VISUAL METEOROLOGICAL CONDITIONS PREVAILED AND NO FLIGHT PLAN WAS FILED. THE PILOT REPORTED THAT HE WAS FLYING AT 200 FEET AGL WHEN HE FELT THE HELICOPTER BEGIN TO SHAKE. AS HE REDUCED THE POWER, THE HELICOPTER STOPPED SHAKING. THE PILOT AUTOROTATED AND LANDED IN AN AREA OF HILLY AND UNEVEN TERRAIN. THE TAIL ROTOR BLADES IMPACTED AN EMBANKMENT AND THE MAIN ROTOR BLADES SEVERED THE TAILBOOM. (.4) THE PILOT ENCOUNTERED RETREATING BLADE STALL WHILE FLYING AT 100 MPH. HE REPORTED THAT THE HELICOPTER BEGAN TO SHAKE AND IT FELT LIKE AN 'OUT OF BALANCE FEELING, LIKE WHEN THE WASHING MACHINE GETS UNBALANCED.' THE ROTOR RPM BEGAN TO DECAY. WHEN HE REDUCED POWER AND STABILIZED THE AIRSPEED ABOUT 60 TO 65 MPH, THE SHAKING STOPPED. THE PILOT STATED THAT HE WAS NOT ABLE TO MAINTAIN LIFT, SO HE ENTERED AN AUTOROTATION OV ER THE HILLY TERRAIN. THE TAIL ROTOR BLADES IMPACTED AN EMBANKMENT AND THE MAIN ROTOR BLADES SEVERED THE TAIL BOOM. THE PILOT'S MANUAL FOR THE BELL 47G2 INDICATES THAT THE 'NEVER-EXCEED SPEED' (VNE) FOR THE HELICOPTER IS 100 MPH. ACCORDING TO THE FAA'S BASIC HELICOPTER HANDBOOK, THE RECOVERY PROCEDURE FOR RETREATING BLADE STALL IS TO REDUCE THE COLLECTIVE PITCH, INCREASE ROTOR RPM, REDUCE FORWARD AIRSPEED, AND MINIMIZE MANEUVERING.
NTSB investigation
The NTSB’s investigation of this event, with its probable cause and findings. Matched to this report by N-number and date.
Other reports on N9021R · 3
Matched to the same aircraft by N-number and date.