Incident Overview
Approximately 90 minutes after departure, the captain reported that the aircraft experienced an abrupt pitch-up followed by an abrupt pitch-down. During this event, one flight attendant sustained serious injuries, while two other flight attendants and one passenger received minor injuries. The autopilot was disengaged, and the flight returned to Los Angeles, where the aircraft landed without further incident.
Investigation Findings
An investigation into the incident revealed that the output from the number two (first officer's) control wheel sensor, part number 1936100-4, had become erratic. This malfunction was identified as the cause of the abnormal pitch behavior.
Operational Response
After the pitch upset, the flight crew took manual control by disengaging the autopilot and successfully returned the aircraft to its departure airport. The landing was completed without any additional issues.