What happened
On June 16, 2017, a Schempp-Hirth Discus 2cT motor glider departed from the Rheinstetten glider airfield via winch launch for a cross-country flight. Following the launch, the pilot performed a routine engine test at a safe altitude, as previously advised by a club member due to a recent ignition cable replacement. The engine test was successful, and the pilot continued the flight toward Landau/Pfalz in a gliding configuration.
As thermal conditions deteriorated around 14:30, the pilot attempted to restart the engine at approximately 350 meters above ground level to assist with a return to the departure airfield. Although the engine started, the RPM remained low at approximately 1,600, providing insufficient power for a positive climb. Consequently, the pilot decided to retract the engine and perform an off-field landing in a field near Wörth am Rhein.
During the landing at approximately 14:35, the aircraft's main landing gear struck a massive steel irrigation pipe running perpendicular to the landing direction. The pipe was hidden beneath the crops in the field. The impact abruptly stopped the aircraft and caused it to rotate 90 degrees, resulting in severe injuries to the pilot and heavy damage to the aircraft.
The investigation
The BFU examined the aircraft and the site of the accident. The investigation included a review of the pilot's flight experience, the aircraft's maintenance history, and the meteorological conditions at the time. The BFU also reviewed GPS data from a navigation and collision warning device, as the aircraft was not equipped with a flight data recorder or cockpit voice recorder.
Post-accident inspections of the engine revealed that the engine could be extended without difficulty and that the spark plugs were dry and normal. A subsequent engine test performed at a maintenance facility by the owner's request revealed that while the engine would start, it failed to reach operating RPM and eventually stalled. This was attributed to a faulty front ignition system, which was replaced, after which the engine functioned normally.
Findings
- The primary cause of the accident was the collision with a hidden steel irrigation pipe that was not visible between the crops.
- The pilot's decision to perform an off-field landing was necessitated by the engine's inability to maintain sufficient RPM for a climb.
- The impact caused significant structural damage to the main landing gear, the lower fuselage, and the cockpit canopy, as well as various scrapes and soil adhesion on the wings.