Uncommanded Spoiler Extension on SATA International Flight RZO-128 (CS-TKM)

Incident Overview and Flight History On 28 January 2007, SATA International Flight RZO-128 departed Ponta Delgada (LPPD) at 22:35 UTC, bound for Lisbon (LPPT). The aircraft was an Airbus A310, serial number 661, registration CS-TKM, carrying 9 crew members and 181 passengers. Shortly after passing the BEKUN position and leveling off at 38,000 feet with autopilot 2 engaged, spoiler 6R extended fully without any intentional speed brake selection or bank maneuver. The aircraft was stable in altitude and speed, with no turbulence reported. ## Crew Response and Diversion The crew executed the spoiler fault checklist, but spoiler 6R remained fully extended even after hydraulic pressure was cut. During the abnormal checklist, autopilot 2 disengaged and the aircraft entered a Dutch roll. The crew maintained manual control, descended to a lower altitude, reduced speed, and re-engaged the autopilot in CWS mode. Due to the asymmetric flight condition with a tendency to turn right, the crew applied differential thrust by reducing the right engine (#2) and accelerating the left engine (#1). Citing difficulty in controlling the aircraft, the crew decided to divert to Santa Maria (LPAZ), where the aircraft landed at 00:20 UTC the following day without further issues. ## Injuries, Damage, and Investigation Findings No injuries were reported among the 9 crew members and 181 passengers, all of whom evacuated the aircraft by their own means. The aircraft sustained no damage, though corrective maintenance was required before it could continue to its destination. The flight data recorder and quick access recorder were removed and analyzed; the quick access recorder data was provided to Airbus. The cockpit voice recorder was not removed in time, and relevant data was overwritten. ## Servo-Valve Examination A maintenance team was sent to Santa Maria to restore airworthiness. The faulty servo-valve (P/N: 73020; S/N: 2656-A) was replaced and tested successfully. For fault-finding purposes, the same servo-valve was installed in the corresponding position on the left wing. Upon pressurization, spoiler 6L extended without any selection, confirming the fault. The servo-valve was permanently removed and sent for further investigation. Preliminary examinations indicated an electrical fault (ground leak) in the servo-valve. The component was sent to Parker Hannifin GmbH & Co.KG in Mainz-Kastel, Germany, for forwarding to the manufacturer, Abex/Parker, in Dublin, Georgia, USA, but it was lost in transit and never received by the manufacturer. No prior records of spoiler system failures were found in the aircraft's technical logs.