What happened
On June 21, 2022, a Cessna 525 A departed from Sylt Airport (EDXW) bound for Hannover. The aircraft was occupied by two pilots and two passengers. During the initial climb, the crew detected vibrations throughout the airframe and observed visible fluttering of the ailerons.
In response to the instability, the crew immediately executed a turn to return to the departure airfield. The aircraft landed on the opposite direction of the takeoff runway at Sylt at approximately 12:02 PM. The crew noted that the fluttering sensation subsided as the aircraft decelerated during the final approach. There were no injuries to the occupants and no damage to the aircraft or third-party property.
The investigation
The BFU investigation focused on the mechanical state of the flight controls following the occurrence. A post-flight inspection of the aircraft revealed that the connection to the aileron trim tab was missing.
Specifically, the linkage between the control mechanism and the trim tab is comprised of two pushrods. These rods are secured to the trim tab using clevis ends, hexagonal bolts, washers, castle nuts, and cotter pins. Investigators determined that the hardware required to secure these two connections—including the bolts, washers, and nuts—was entirely absent from the assembly and could not be located.
Records indicated that maintenance work had been performed on the aileron trim system on June 1, 2022, approximately three weeks prior to the incident. This maintenance was conducted by a certified PART 145 maintenance organization, and a Release to Service had been issued following the completion of the work.
Findings
- The primary cause of the aileron flutter was a disconnected aileron trim tab linkage.
- The hardware necessary to secure the pushrod clevis ends to the trim tab, including the bolts, washers, and castle nuts, was missing from the aircraft.