What happened
On March 20, 2001, an Airbus A320-200 departed from runway 18 at Frankfurt/Main, bound for Paris. The aircraft was carrying 115 passengers and 6 crew members. Immediately after takeoff, the aircraft developed a left bank. The pilot flying attempted to correct the roll using the left sidestick, but the bank increased continuously, reaching approximately 22 degrees. The captain reported that he could no longer maintain control, prompting the second pilot to take over by pressing the take-over push button.
After stabilizing the aircraft at flight level 120 using the second autopilot, the crew performed a flight control check. During this procedure, the crew discovered that while the right sidestick functioned normally, inputs to the left sidestick caused the aircraft to react in the opposite direction after a brief vibration. Realizing the severity of the malfunction, the crew aborted the flight and returned to Frankfurt, where the aircraft landed safely without any injuries or damage to the aircraft or third parties.
The investigation
The BFU investigation focused on recent maintenance performed on the aircraft two days prior. The aircraft had been in the hangar to address issues with one of the two Elevator-Aileron Computers (ELAC). During the repair, a bent pin was discovered on the ELAC#1 connector, necessitating a complete replacement and rewiring of the connector.
Investigators examined the maintenance documentation, the quality management systems of both the airline and the maintenance provider, and the oversight provided by the Luftfahrt-Bundesamt (LBA). The investigation also reviewed the crew's use of the "After Start Checklist" and the effectiveness of the flight control checks performed prior to departure.