Accident Overview
On March 9, 2011, about 1230 central standard time, a Robinson R22 helicopter (registration N112HE) impacted terrain following an autorotation from cruise flight near San Antonio, Texas. The aircraft was operated by Heliflight Leasing, LLC of Bulverde, Texas, under 14 CFR Part 91 as an instructional flight. Visual flight rules conditions prevailed, and no flight plan was filed. The flight originated from Bulverde Airpark (1T8).
Sequence of Events
The certified flight instructor (CFI) reported that they were practicing autorotations. During the final autorotation, the helicopter repeatedly yawed left and right. The CFI took control, executed a 180-degree right turn, and aimed for a pecan orchard. The helicopter impacted the ground and pecan trees. The main rotor struck the ground, and the helicopter came to rest on its left side. The tailboom separated into two pieces near mid-span, and the fuselage and main rotor blades sustained substantial damage. Neither the CFI nor the student pilot was injured.
Investigation Findings
An FAA inspector noted that the fuel cap was missing from the left-side fuel tank. Backtracking the helicopter's flight path, the inspector located a piece of tailrotor blade and the fuel cap, which had separated into two parts. The fuel cap's gasket was missing; it could not be determined if the gasket had been on the cap before separation. The cap was not equipped with a lanyard chain and had not originally been designed with one. Impact marks on the fuel cap and tailrotor blade piece were consistent with the fuel cap striking the tailrotor blade. The CFI had refueled the helicopter before the flight, and the student pilot performed the preflight inspection.
Additional Information
The NTSB database contained records of two similar events: on July 10, 2011, a Robinson R22 near West Palm Beach, Florida, had a fuel cap separate and lodge in the tailrotor system; and on December 2, 1992, a Robinson R22 near Fresno, California, had a fuel cap come off and strike a tailrotor blade. The helicopter manufacturer subsequently issued R22 Service Bulletin SB-107 (dated May 30, 2012), which noted that improperly secured fuel caps may come off in flight and required application of alignment marks and inspection or replacement of the cap's gasket.