What happened
On February 2, 2010, a Cessna 425 was conducting a night positioning flight from Hannover to Munich under instrument flight rules (IFR). During the descent phase, the crew observed significant issues with the left engine, noting that the interstage turbine temperature (ITT) had exceeded 900 °C and the torque had dropped to zero. In response, the crew decided to shut down the left engine.
As the aircraft approached Munich, the crew declared an emergency and requested an ILS approach to runway 26L. During the final approach, the aircraft'-s airspeed dropped significantly, reaching levels near the minimum controllable airspeed for a single-engine configuration. The crew attempted to initiate a go-around by increasing power on the remaining right engine. However, the sudden increase in power caused the aircraft to yaw violently to one side. Due to the low airspeed and insufficient rudder effectiveness, the crew was unable to counteract this movement, and the aircraft struck the ground approximately 100 meters before the runway threshold. There were no fatalities, though the aircraft sustained heavy damage.
The investigation
The BFU examined the engine performance, fuel systems, and the flight path recorded by radar. The investigation focused on the technical state of the engines and the crew's adherence to established procedures. Investigators reviewed the cockpit actions during the engine shutdown and the subsequent approach, as well as the crew's training and coordination levels.
Findings
- The investigation found no technical evidence of a malfunction that would have necessitated the preemptive shutdown of the left engine.
- When shutting down the left engine, the crew failed to feather the propeller, leaving it in a high-drag position.
- During the final approach, the aircraft's speed was significantly below the prescribed minimum speed for an approach with an inoperative engine.
- The loss of control was caused by the high drag from the unfeathered propeller combined with the sudden application of power to the right engine, which induced a yaw that could not be corrected at low speeds.
- Contributing factors included the crew's failure to follow checklists during the engine shutdown and poor crew resource management (CRM) and coordination.