N111VA

On August 26, 2006, at 1325 Pacific daylight time, the main rotor blades of a Sikorsky S-55, N111VA, clipped tree branches following a precautionary landing in Paramount, California. Internal ribs were damaged in the blades. The pilot was operating the privately registered helicopter under the provisions of 14 Code of Federal Regulations Part 91. The commercial pilot and non-pilot rated passenger were not injured; the helicopter sustained substantial damage. Visual meteorological conditions prevailed, and no flight plan had been filed for the ferry flight that was ultimately destined for Falcon Field Airport, Mesa, Arizona, with a planned refueling stop at Banning Municipal Airport, Banning, California. The helicopter departed from Compton/ Woodley Airport, Compton, California, at 1306.

The National Transportation Safety Board investigator interviewed the pilot. He indicated that a Federal Aviation Administration (FAA) ferry permit had been issued for the helicopter that was out of its annual inspection requirements. He was repositioning the helicopter to Mesa to undergo an annual inspection. During cruise flight at 550 to 600 feet above ground level (agl) he leaned the mixture setting. Shortly thereafter, the engine began sputtering so he applied full mixture. The pilot made an uneventful precautionary landing in a field. Following the landing, he powered up the engine to reposition the helicopter and two of the main rotor blades clipped branches of a nearby tree.

The pilot reported 15,780 hours total flight time with 7,000 hours in helicopters, and 5,000 hours in the accident helicopter make and model. Of the 5,000 hours, the majority of his S-55 piston time was flying with the Wright R-1300 engine; the helicopter was equipped with a Pratt and Whitney R-1340 engine.

The owner stated that he hired the pilot (who is also an Aviation Maintenance Technician with Inspection Authorization) to perform the necessary work to obtain a ferry permit and then to pilot the helicopter to Mesa, to perform an annual inspection. The helicopter had not flown for 2 years, although ground runs of the engine and rotor system were performed biweekly. After the annual inspection, they were to fly the helicopter to Manhattan, New York, for a ceremony. The owner hired the pilot because he had an extensive flying history in the S-55.

The owner picked up the pilot at the airport on August 24, and they reviewed the logbooks and history of the helicopter. The following day, an FAA inspector reviewed the helicopter's maintenance history and issued the ferry permit. That day, the owner and pilot performed additional maintenance items on the helicopter that included servicing the spark plugs and main rotor blades.

The day of the accident the helicopter was fueled at Compton and they departed eastbound for their first planned stop at Banning airport. Five minutes into the flight, at an altitude of 550 to 600 agl, the pilot leaned the fuel mixture 20 to 25 percent. The engine began sputtering and the pilot applied full rich mixture. He then performed an autorotation to a nearby field where the helicopter rolled to a stop underneath some trees. By this time, the engine had regained power. As the owner unbuckled his safety belt, the pilot began to apply power and lifted up on the collective to reposition the helicopter. At this time, the main rotor blades contacted tree branches and the tip caps and blade weights were ripped off. The pilot then shut the engine down.

Under FAA supervision, the carburetor was removed from the helicopter and functionally tested on a test bench. Following the functional test, the carburetor was disassembled. No debris or operational anomalies were noted.

The Sikorsky operational handbook for the helicopter states, "For operations below 5,000 feet, a rich mixture should be maintained."