What happened
On August 13, 2016, at approximately 15:12 local time, a Roman Weller UW 9 "Sprint" ultralight aircraft departed from runway 26 at the Hasselfelde airfield with one occupant. Video footage from a witness captured the aircraft lifting off in a three-point attitude near the halfway runway marking. Shortly after reaching the end of the runway, the aircraft entered a right-hand turn and continued flying in a northerly direction.
Within five seconds of completing this turn, a change in propeller RPM was observed. Immediately following this, the aircraft began a roll around its longitudinal axis to the right. During this maneuver, the ailerons were deflected to the left, while the rudder was deflected to the right and the elevator was in a back-pressure position. Witnesses also noted that the aircraft's nose pitched up just before the rolling motion began. Less than five seconds after the roll commenced, the aircraft struck the ground. The impact was nearly vertical, and the aircraft caught fire immediately upon contact with the terrain.
The investigation
The BFU investigation examined witness video recordings, aircraft wreckage, and pilot records. The investigation confirmed that the aircraft's forward fuselage and wings were destroyed by fire, while the rear fuselage remained partially intact. The damage to the forward sections was consistent with a near-vertical impact. The investigation also reviewed the pilot's credentials, noting a valid license and medical certificate, as well as significant flight experience, including over 150 hours on this specific model.
Technical analysis of the aircraft's weight and balance was conducted. Based on an estimated pilot weight of 85 kg and 72 liters (54 kg) of fuel, the estimated takeoff mass was 448 kg, with a center of gravity located 738 mm behind the datum. This fell within the permitted range of 610 mm to 930 mm specified in the flight manual.
Findings
- The aircraft experienced an uncontrolled roll following a change in engine RPM.
- The pilot's control inputs during the roll included left aileron, right rudder, and back elevator.
- The aircraft struck the ground in a near-vertical attitude.
- The pilot sustained fatal injuries.
- The aircraft was destroyed by the impact and subsequent fire.