|About this Abstract
||Materials Science & Technology 2019
||Failure Analysis: Industry Specific Failures
||Helicopter Main Rotor Servo Disconnect Failure Due to Self-locking Nut Reuse
||Richard McSwain, William Carden, Eric Van Iderstine, Leah Godwin
|On-Site Speaker (Planned)
A helicopter accident investigation revealed that a main rotor servo disconnected in flight. Examination of the accident wreckage showed a missing fastener for the servo that was to be secured with a nylon insert self-locking nut. Laboratory testing of the subject-type fastener and self-locking nut revealed loss of the self-locking feature effectiveness after several installation and removal cycles. It was concluded that the reuse of the nylon insert self-locking nut led to the loss of fastener torque and loss of the main rotor servo fastener in flight.