What happened
On 7 April 2004, a Piper PA-46-350P JetProp, registration D-EMDB, was conducting a flight from Egelsbach, Germany, to Samedan, Switzerland. The flight was planned using a combination of instrument and visual flight rules. Upon approaching the Engadine region, the pilot reported being over the aerodrome and indicated an intention to fly east to find a gap in the cloud cover to facilitate an approach to Samedan.
During this maneuver, the aircraft entered an uncontrolled state. Eyewitnesses observed the aircraft falling from the clouds in a vertical, uncontrolled attitude. The aircraft struck the ground near Madulerm, approximately 12 km northeast of St. Moritz, in what appeared to be a flat spin. The impact resulted in five fatalities, including the pilot and four passengers. The aircraft was destroyed upon impact.
The investigation
Investigators examined the wreckage, the engine monitoring data, and the aircraft's weight and balance records. Technical analysis of the airframe and the Pratt & Whitney Canada PT6A-35 turboprop engine revealed no pre-existing mechanical defects or failures.
Data from the engine trend monitoring system indicated that the aircraft had reached an excessive airspeed during the maneuver, followed by an abrupt correction that dropped the airspeed to below 60 knots. During this period, the engine was operated at a power setting that exceeded the maximum permissible torque. The investigation also recalculated the aircraft's mass, finding that the aircraft was significantly overweight at the time of the accident.
Findings
- The aircraft was exceeding its maximum takeoff mass by approximately 722 lb, and remained roughly 425 lb over the limit at the time of the crash.
- The aircraft was loaded in a tail-heavy configuration.
- The pilot attempted to maneuver through a cloud gap, leading to an overspeed condition and a subsequent rapid deceleration.
- The application of high engine power during a low-speed state likely triggered a stall/spin sequence.
- The combination of high power, low airspeed, and a tail-heavy weight distribution contributed to the development of a flat spin, which is difficult to recover from without specialized training.