Cessna 551 Citation II/SP Accident at Siegerland Airport

Incident Overview and Aircraft Details On 24 April 2019, a Cessna 551 Citation II/SP, manufactured by Cessna Aircraft Company, was involved in an accident at Verkehrsflughafen Siegerland. The aircraft, built in 1987 with serial number 551-0552, was powered by two Pratt & Whitney Canada JT15D-4 turbofan engines. At the time of the accident, it had accumulated 8,479 flight hours and 7,661 landings. The aircraft sustained heavy damage, and the runway asphalt was also damaged. ## Flight Operations and Accident Sequence The flight was a training flight for the pilot to obtain a type rating for the Cessna 551 Citation II/SP. The 70-year-old flight instructor occupied the right pilot seat as the responsible pilot-in-command, while the 36-year-old student pilot, who had passed the theoretical exam for the type approximately one week prior, was the pilot flying from the left seat. The student had completed about three hours of flight time in the aircraft the previous day. The flight departed from Flugplatz Reichelsheim at 13:30 local time under visual flight rules. Upon arrival at Siegerland Airport, the crew conducted three precision approaches using the Instrument Landing System (ILS) to Runway 31. Following the third landing, the air traffic controller changed the landing direction to Runway 13 due to wind conditions. The crew taxied to the end of the runway, turned around, and took off at 14:34. After a left traffic pattern at 3,500 ft AMSL, the crew conducted a visual approach to Runway 13 under visual meteorological conditions without using the ILS. During the final approach, the student pilot reported that the airspeed decreased and he felt the aircraft was flying too low, requiring a correction to the approach angle. He advanced the engine thrust levers to the maximum forward position, an action supported by the flight instructor. However, the instructor stated that there was insufficient time before landing for the engines to reach maximum rotational speed and provide the necessary thrust. The instructor also noted that the aircraft was in the stall speed range, although he did not perceive a stall warning. At 14:42, the aircraft landed with the landing gear extended in the grass area before the threshold of Runway 13. The left main landing gear collapsed, damaging the fuel tank in the left wing. The right main landing gear also collapsed, but the right wing tank remained undamaged. Jet fuel leaking from the left wing ignited, causing a fire. The aircraft slid along Runway 13 on its collapsed landing gear, fuselage underside, and extended landing flaps, coming to a stop approximately 730 meters from the runway threshold. After the aircraft stopped, the student pilot noticed flames on the left side. The flight instructor shut down both engines, and both pilots evacuated through the emergency exit door on the right side. The student pilot stated that the emergency checklist from the Quick Reference Handbook (QRH) was not used during the evacuation. Neither pilot was injured. ## Meteorological and Wind Conditions At the time of the incident, it was daylight. According to the METAR report from Siegerland Airport at 14:20, horizontal visibility was greater than 10 km. The wind was from 220° at 6 kt, variable from 100° to 240°. There were no clouds below 5,000 ft AMSL. The temperature was 21 °C, the dew point was 8 °C, and the QNH was 1,003 hPa. Radar data from the German Weather Service (DWD) provided by the airport tower indicated the wind conditions for each approach. For the fourth and final approach, which was visual, the ground speed was 97 kt, and the wind was from 094° at 3 kt, resulting in a headwind component of approximately 2 kt relative to the runway. The previous three ILS approaches to Runway 31 had tailwind components of approximately 3 to 5 kt. ## Aircraft Weight and Speed Data Based on the aircraft's empty weight, including the two pilots and the fuel on board, the German Federal Bureau of Aircraft Accident Investigation (BFU) calculated the landing weight for the final approach to Runway 13 to be approximately 12,000 lbs. The flight instructor reported that before the final takeoff from Runway 13, there was approximately 1,322 lbs (about 600 liters) of jet fuel in each wing tank. For a landing weight of 12,000 lbs, the approach speed (VREF) was 106 kt. The stall speed (VS) in the landing configuration for this weight was 80 kt, according to the Airplane Flight Manual. ## Engine Performance Data According to Engine Service Bulletin No. 7124, Rev. No. 3, dated 28 June 1979, for the Pratt & Whitney Canada JT15D-4 engine, the time to accelerate from IDLE to 95% N1 at an outside air temperature of 15 °C and an air pressure of 1,013.25 hPa is up to 4.5 seconds.