Summary
On July 29, 2009, a Robinson Helicopter R22 BETA (N7176W) was involved in an accident near Troutdale, OR. The accident resulted in 2 minor injuries. The aircraft sustained substantial damage.
The National Transportation Safety Board determined the probable cause of this accident to be: The flight instructor's failure to maintain adequate main rotor RPM.
After practicing a series of autorotations, the flight instructor and his student attempted to complete a 180-degree autorotation. The student began a stabilized autorotation from the downwind leg of the traffic pattern. According to the flight instructor, during the turn the student allowed the nose of the helicopter to drop; he was instructed to correct this attitude by applying aft cyclic. When the student completed the turn at an altitude of 200 to 250 ft agl and at a speed of 80 to 85 knots, the flight instructor believed that the outcome of the maneuver was in doubt. The flight instructor then took control of the helicopter and began to initiate a recovery by raising the nose and attempting to increase the throttle and collective to arrest the descent rate.
This accident is documented in NTSB report WPR09CA375. AviatorDB cross-references NTSB investigation data with FAA registry records to provide comprehensive safety information for aircraft N7176W.
Accident Details
Probable Cause and Findings
The flight instructor's failure to maintain adequate main rotor RPM.
Aircraft Information
Registered Owner (Historical)
Analysis
After practicing a series of autorotations, the flight instructor and his student attempted to complete a 180-degree autorotation. The student began a stabilized autorotation from the downwind leg of the traffic pattern. According to the flight instructor, during the turn the student allowed the nose of the helicopter to drop; he was instructed to correct this attitude by applying aft cyclic. When the student completed the turn at an altitude of 200 to 250 ft agl and at a speed of 80 to 85 knots, the flight instructor believed that the outcome of the maneuver was in doubt. The flight instructor then took control of the helicopter and began to initiate a recovery by raising the nose and attempting to increase the throttle and collective to arrest the descent rate. According to the flight instructor, the RPM decayed and the low rotor rpm horn came on at 150 to 100 ft agl. The helicopter landed hard and subsequently slid off the north side of the taxiway. The forward section of the left skid contacted the soft dirt, which resulted in the helicopter turning to the left and nosing over. Examination of the aircraft by a Federal Aviation Administration inspector revealed substantial damage to the helicopter consisted of the separation of the tail boom assembly, damage to the firewall, the left forward frame, and left skid support structure. The flight instructor reported no mechanical anomalies with the helicopter or flight control systems.
Data Source
Data provided by the National Transportation Safety Board (NTSB). For more information on this event, visit the NTSB Records Search website. NTSB# WPR09CA375