What happened
On November 30, 2013, an EV 97 Eurostar 2000 R ultralight aircraft departed from the Rheine-Eschendorf airfield for a local flight. Shortly after takeoff, the aircraft climbed to 1,700 ft before changing course toward the north-northwest and descending to approximately 1,000 ft. At approximately 13:43, witnesses observed the aircraft plunging nearly vertically toward the ground. The aircraft struck a harvested cornfield near Beesten, resulting in the fatal injury of the pilot and the destruction of the aircraft.
The investigation
The BFU investigation focused on the mechanical failure of the propeller and the maintenance history of the aircraft. Investigators recovered a detached propeller blade from the wreckage, while the second blade remained attached to the hub. The investigation established that the loss of the blade created a severe imbalance, generating intense vibrations. These vibrations were powerful enough to force the cockpit canopy open during flight, allowing various cockpit items to be scattered across the landscape. The investigation also examined the maintenance records of the Woodcomp Varia propeller and the communication between the propeller manufacturer and the aircraft's maintainer.
Findings
- The primary cause of the accident was the separation of a propeller blade during cruise flight.
- The resulting propeller imbalance caused extreme vibrations that caused the cockpit canopy to fly open, leading to a loss of aircraft control.
- The propeller had exceeded its required 150-hour inspection interval, having been operated for 266 hours since its last manufacturer-led inspection.
- A significant contributing factor was a linguistic misunderstanding regarding maintenance intervals. The manufacturer used the non-standard term "immensity 300 hours" on a confirmation form. The aircraft maintainer interpreted this to mean the propeller could be flown for an additional 300 hours, whereas the manufacturer intended it to mean the next inspection was due at the 300-hour total time mark.
- The failure of the aircraft's emergency rescue system to deploy also contributed to the severity of the fatal outcome.