Polish Aviation Commission Concludes Investigation of Saab 340 Takeoff Incident

Incident Overview and Investigation Authority On December 18, 2012, the Polish State Commission for Investigation of Aviation Accidents (Państwowa Komisja Badania Wypadków Lotniczych) reviewed the operator's findings regarding an incident involving a Saab 340 aircraft. The event occurred on November 9, 2011, during a takeoff from the EPWR airfield. Acting under European Regulation (EU) No 996/2010, the Commission accepted the operator's investigation results and formally closed the case. ## Operational Context and Event Sequence The flight crew was operating the third scheduled passenger flight of the day on the route from EPWR to EDDT. The captain was the pilot flying, while the first officer was monitoring. The aircraft's takeoff weight was 11,000 kg, with calculated speeds of V1 at 111 knots, Vr at 114 knots, and V2 at 116 knots. Following air traffic control clearance, the crew began the takeoff roll on runway 29. The Constant Take-Off Torque (CTOT) system was set to 96% and activated at the captain's command. Initially, the system functioned correctly, with both engines reaching approximately 98% torque and an exhaust gas temperature of 820°C. ## Anomaly and Response Approximately three to four seconds after the start of the roll, the first officer reported a failure. The left engine (No. 1) torque indicator rose to about 115% and oscillated before dropping to 30%. The crew felt a pull to the left and observed a drop in the left engine's exhaust gas temperature to approximately 700°C. The captain decided to abort the takeoff and set the power levers to ground idle. The first officer notified air traffic control and received clearance to taxi via taxiway D4 to Apron 4 with follow-me assistance. During the taxi, both engines showed normal readings. After the engines were shut down, the captain performed an external inspection, and the passengers were transported to the terminal. ## Technical Findings and Conclusion Subsequent electrical measurements and ground tests revealed a malfunction in the CTOT system, specifically a delayed activation of the left engine's CTOT. The faulty panel was replaced, and the aircraft was returned to service under the Minimum Equipment List (MEL) without an active CTOT system. The incident did not recur after the repair. The Commission identified the cause of the incident as a failure and malfunction of the CTOT control panel. Preventive measures included briefing the remaining flight and technical personnel about the event. The Commission did not issue any safety recommendations.