CEN17LA099

The helicopter experienced a loss in rotor rpm while maneuvering during a low-level wildlife survey. The commercial pilot then performed a forced landing to a field. Postaccident examination of the helicopter revealed that one of the engine magnetos had an internal timing, efficiency gap failure, which would have resulted in improper engine ignition timing and loss of engine power/rpm. Examination also revealed that the magneto distributer gear was loose and that the distributer gear bushing was flapping around.

On October 28, 2016, at 1000 central daylight time, a Robinson Helicopter R22 Beta, N522KC, impacted terrain during a forced landing after a partial loss of engine power near Asherton, Texas. The helicopter sustained substantial damage. The pilot was uninjured. The helicopter was registered to Rotor Spec Aviation LLC and operated by the pilot under Title 14 Code of Federal Regulations Part 91 as an aerial wildlife survey flight that was not operating on a flight plan. Day visual meteorological conditions prevailed at the time of the accident. The local flight originated from Asherton, Texas at time unknown. A National Transportation Safety Board (NTSB) Pilot/Operator Aircraft Accident/Incident Report was not received from the pilot. According to a Federal Aviation Administration inspector, the helicopter experienced a loss in rotor rpm while maneuvering at low level during a wildlife survey. The pilot then performed a forced landing to a field. Post-accident examination of the helicopter revealed a failure of one of the engine magnetos. The wreckage had been moved and sold by the operator without the knowledge of the Federal Aviation Administration inspector and the NTSB. The NTSB Investigator-in-Charge located the engine at an engine maintenance facility whose representative stated that he examined the engine magnetos and one of the magnetos, Bendix model number S4LSC-200, part number 10-600614-1, serial number J229358E, had an internal timing, efficiency gap (E-gap) failure. He said the magneto distributer gear was loose, and the distributer gear bushing was "flapping" around.