On March 9, 2011, about 1230 central standard time, a Robinson R22 helicopter, N112HE, impacted terrain following an autorotation from cruise flight, after the helicopter developed a vibration and yaw near San Antonio, Texas. The certified flight instructor (CFI) and student pilot were not injured and the helicopter was substantially damaged. The aircraft was registered to and operated by Heliflight Leasing, LLC., Bulverde, Texas, under the provisions of 14 Code of Federal Regulations Part 91 as an instructional flight. Visual flight rules (VFR) meteorological conditions prevailed at the time of the accident and a flight plan was not filed. The flight originated from the Bulverde Airpark (1T8), San Antonio, Texas. According to the CFI, they were practicing autorotations and as they entered the last autorotation the helicopter yawed to the left and right repeatedly. The CFI took control of the helicopter and made a 180-degree turn to the right, in order to land in a pecan orchard. The helicopter impacted the ground and pecan trees. The helicopter’s main rotor contacted the ground and the helicopter came to rest on its left side. During the impact the tailboom separated into two pieces near mid-span and the fuselage and main rotor blades were substantially damaged. The responding Federal Aviation Administration (FAA) Inspector noted that the helicopter’s fuel cap was missing from the left side fuel tank. The inspector back-tracked the helicopter’s general direction of flight and located a piece of the tailrotor blade and fuel cap, which had separated into two parts. Additionally, the fuel cap’s gasket was missing. It could not be determined if the gasket was on the fuel cap prior to separating from the helicopter. It was also noted that the fuel cap did not have a lanyard chain, nor was it originally equipped with one. The impact marks on the fuel cap and rotor blade piece were consistent with the fuel cap coming into contact with the tailrotor blade. The inspector also noted that prior to the flight, the CFI had refueled the helicopter, and the student pilot pre-flighted the helicopter. Additional Information A search of the NTSB database for similar events revealed two such occurrences: On July 10, 2011, a Robinson R22 helicopter, near West Palm Beach, Florida, had a fuel cap separate and lodge in the tailrotor system. (NTSB preliminary report ERA11LA392) On December 02, 1992, a Robinson R22 helicopter, near Fresno, California, had a fuel cap come off and struck a tailrotor blade. (NTSB report LAX93LA058) The helicopter manufacturer issued R22 Service Bulletin, Number SB-107, dated 30 May, 2012, that notes improperly secured fuel caps may come off in flight. The bulletin requires the application of alignment marks and inspection/replacement of the cap’s gasket.