What happened
On 10 January 2012, an Aeroplam A22L Foxbat, registration G-CGWP, was conducting a private flight from Enstone Airfield in Oxfordshire. Approximately four minutes after departure, while climbing through 2,000 feet, the aircraft began to vibrate violently. The pilot initially suspected an engine issue and reduced power, which temporarily halted the shaking. However, the aircraft then experienced a significant rudder jam accompanied by a yaw to the right.
Upon applying left rudder pressure, the pilot heard a loud bang, after which the rudder returned to a neutral position before jamming again. Simultaneously, the elevator also became jammed. The pilot declared a PAN and returned to Enstone, opting to keep the flaps retracted to prevent pitch changes. Although the aircraft touched down normally on its main wheels, the nosewheel—which is linked to the rudder—became uncontrollable. This caused the aircraft to depart Runway 26 and travel onto the grass.
The investigation
An engineer from the Light Aircraft Association (LAA) inspected the aircraft to determine the cause of the control failure. The investigation revealed that the rudder anti-balance tab had separated from the rudder at the lower hinge. This separation allowed the tab to move aft, which subsequently damaged the elevator. The damage to the elevator was consistent with the control horn bending downwards, and the control horn cable had also failed.
Investigators found that the screw and nut intended to secure the lower tab hinge were missing, and the remaining top hinge screws were loose. There was also evidence of rubbing on the leading edge of the tab. While the exact trigger for the initial flutter could not be definitively identified, the engineer theorized that the failure of the lower hinge screw likely allowed the tab to move aft, initiating the flutter and the subsequent mechanical jams.