NTSB Factual Report

On July 10, 2011, about 0910 eastern daylight time, a Robinson R22 BETA, N10786, operated by Ocean Helicopters Inc., was substantially damaged during an autorotation, following a system malfunction during initial climb from Palm Beach International Airport (PBI), West Palm Beach, Florida. The certified flight instructor (CFI) was not injured and the student pilot incurred minor injuries. The instructional flight was conducted under the provisions of 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed and no flight plan was filed for the planned local flight, which departed PBI about 0840.

According to the CFI, he and the student pilot performed five or six quick-stops. They then proceeded with a normal takeoff. About 200 feet above the ground, the helicopter yawed right, which was unable to be corrected with left pedal input. The CFI then entered an autorotation as the helicopter continued to yaw right. He also observed that the horizontal and vertical stabilizers had separated from the tailboom and were falling to the ground.

According to a Federal Aviation Administration inspector, a fuel cap separated and entered the tail rotor system, resulting in a tailrotor imbalance and partial separation. The helicopter subsequently spun during the autorotation and landed hard. During the impact, the tail rotor separated and the fuselage sustained substantial damage.

The fuel cap had separated from the right fuel tank, which was the auxiliary fuel tank, and was not serviced prior to the accident flight. The separated fuel cap was recovered and was missing its restraining chain and gasket. Both pilots reported that they checked the fuel caps during preflight inspection. Additionally, the main fuel tank (left) cap had remained secured throughout the accident sequence. Examination of the main fuel tank cap revealed that it did contain a gasket, but not a chain.

Review of helicopter manufacturer data revealed that on November 22, 1993, the manufacturer ceased installing restraining chains on its fuel caps; however, production of the accident helicopter was completed in January, 1993, and it should have left the factory with restraining chains attached to the fuel caps.

Review of the helicopter's maintenance records did not reveal any instance of the fuel cap restraining chains being removed in the field.

NTSB Probable Cause

Separation of the auxiliary fuel tank cap, which entered the tail rotor system. Contributing to the accident was the lack of a fuel tank cap restraint.