What happened
Shortly after takeoff, the flight crew of the Airbus A320 experienced a high-frequency vibration that was perceptible through the control column and at the crew's feet. Although the engine indicating and alerting system displayed no messages, the slow-frequency vibration increased in intensity over approximately 30 seconds.
As the aircraft climbed toward its cleared altitude of 17,000 feet, it began an uncommanded roll to the right. The first officer disconnected the autopilot to regain manual control of the aircraft. Following the event, the captain declared an emergency, and the crew was cleared to proceed to an alternate airport. The vibrations persisted throughout the descent and continued during the landing phase.
The investigation
Mechanical examination of the aircraft focused on the aileron system. Investigators discovered that the bushings and the inboard and outboard power control unit output links for the right aileron were worn. This wear exceeded the tolerances permitted by the maintenance manual. Additionally, it was noted that the manufacturer's inspection procedures for checking aileron system backlash did not require the operator to record the specific tolerances found during the check.