Rotor Control Problem May Have Preceded Crash
The NTSB says one end of a rotor servo control rod was found disconnected on an A350 helicopter that crashed on the Hawaiian island of Kauai earlier this month, killing four of seven people aboard. On Thursday, the FAA issued a special airworthiness information bulletin (SAIB) and Eurocopter e-mailed customers warning A350 operators that a serrated washer on the servo rod-end could fail, resulting in disconnection of the rod from the rotor assembly, and recommended immediate inspection of those parts. The A350 has three such assemblies to control rotor tilt. The SAIB issued by the FAA says two crashes have been caused by the washer failure, but spokesman Ian Gregor said those crashes occurred before the Hawaii accident and the bulletin was already in the works when the Heli-USA helicopter crashed on landing at Princeville Airport on March 8. Pilot Joe Sulak and three passengers died in the crash. Before the accident Sulak radioed that he was having “hydraulic problems.” Investigators later found the detached servo rod and sent those parts for more detailed inspection. The washer identified in the FAA and Eurocopter bulletins has a tang that is supposed to lock in the threads of the rod end to prevent the bolt from unscrewing. In the previous crashes, the tang was missing or worn and allowed the nut securing the rod to the rotor assembly to come off.