Accident Overview
On March 15, 2012, at approximately 1645 Pacific daylight time, a Robinson Helicopter R22 Beta, registration N290SH, made a hard landing at Palo Alto Airport in Palo Alto, California, following a loss of engine power. The helicopter was registered to Parker Helicopter LLC and operated by Sirius Flying, LLC under Part 91 of the Federal Aviation Regulations. The pilot sustained a minor injury, and the helicopter sustained substantial damage.
Flight Details
The local instructional flight departed Palo Alto at 1640 PDT. Visual meteorological conditions prevailed, and no flight plan was filed. According to the operator, the pilot reported that while on the downwind leg, just prior to turning base, the helicopter experienced a loss of main rotor RPM. The pilot entered an autorotation and found the throttle unresponsive. During the forced landing into a marsh area, the helicopter rolled over.
Pilot Information
The pilot, aged 50, held a commercial pilot certificate with ratings for airplane single-engine land, glider, and instrument airplane, and a certified flight instructor certificate with ratings for airplane single-engine land and instrument airplane. She was operating the helicopter under a student pilot certificate. She held a third-class medical certificate issued on March 21, 2011, with a limitation requiring corrective lenses. The pilot reported 46 hours of total helicopter time, with 8 hours as pilot-in-command, and 750 hours total time in all aircraft.
Weather Conditions
Weather at the time of the accident, recorded at 1647, included wind from 270 degrees at 10 knots, temperature 63 degrees Fahrenheit, and dew point 55 degrees Fahrenheit. The carburetor icing probability chart from FAA Special Airworthiness Information Bulletin CE-09-35 indicated a probability of serious icing at glide power under these conditions.
Post-Accident Examination
Investigators examined the wreckage at Plain Parts in Sacramento, California, on April 25, 2012. The engine was started and run at idle until warm, then run up to 100 percent. The magnetos were tested; the right magneto showed an excessive RPM drop, while the left magneto was within limits. After swapping the bottom spark plugs from cylinders 4 and 3, the engine was restarted and both magneto tests were within limits. The post-accident examination revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation.
Additional Information
The pilot's flight instructor stated that the pilot had a history of inadvertently gripping the throttle on the collective, which would override the governor and cause a low rotor condition. The instructor had previously intervened to correct such conditions. The pilot submitted a Pilot/Operator Aircraft Accident Report (NTSB Form 6120.1/2) with the assistance of legal counsel. In a meeting with FAA inspectors on March 26, 2012, the pilot stated she was unable to provide details about the accident due to the event being too traumatic to recall. The attorney confirmed he wrote the statement submitted to the NTSB.