What happened
On June 28, 2010, a Comco Ikarus C 42 ultralight aircraft departed from the Vettweiß-Soller grass airstrip for a local pleasure flight. The aircraft was occupied by the pilot and a 9-year-old passenger. Witnesses observed the aircraft performing a shallow initial climb from runway 32. Shortly after takeoff, at an altitude of approximately 30 to 50 meters, the aircraft entered a left-hand bank and began to stall. The aircraft completed a 180-degree turn before impacting a cornfield located 66 meters northwest of the airfield.
The impact caused the pilot to be ejected from the cockpit, resulting in fatal injuries. The young passenger sustained serious injuries. Witnesses reported hearing engine surges and a total engine failure prior to the crash.
The investigation
The BFU investigation focused on the mechanical condition of the Rotax 912 UL engine and the structural integrity of the aircraft. Investigators examined the wreckage, noting that the cockpit area was destroyed and the pilot's seat harness attachments had failed upon impact.
Technical examination of the engine revealed that the Time Between Overhaul (TBO) had been exceeded. While investigators found no definitive cause for a total engine failure, they could not rule out a loss of power. The investigation also identified improper repairs to the ignition system, where wires had been soldered to SMD modules using inappropriate cabling, and noted that the bypass line lacked the required check valve. Additionally, the crankshaft exhibited a runout of 0.52 mm, significantly exceeding the manufacturer's limit of 0.08 mm.
Findings
- The engine's TBO had been exceeded.
- Maintenance records were incomplete, and there was no evidence that periodic inspections had been documented.
- The pilot's seat harness and shoulder strap attachments failed during the impact, leading to the pilot being ejected.
- The primary cause of the accident was the aircraft falling below its minimum flying speed at a low altitude during the climb, which may have been precipitated by a loss of engine power.