2010 Comco Ikarus C 42 accident at Vettweiß

Accident overview and flight details On 28 June 2010, a Comco Ikarus C 42 ultralight aircraft crashed into a cornfield near Vettweiß, Germany, after departing on a local flight. The aircraft was operating from the Vettweiß-Soller ultralight airfield, located south of Düren, and was carrying a pilot and a 9-year-old passenger. Witnesses reported that the aircraft had been refueled from a jerrycan and that a pre-flight inspection had been carried out before takeoff. The aircraft took off from grass runway 32 at approximately 19:54 local time. After an initial shallow climb, it was observed to roll left at an altitude of about 30 to 50 metres above the ground, turn through 180 degrees, and strike the ground in a cornfield beside the airfield. The pilot was ejected during impact and killed, while the passenger sustained serious injuries. Witnesses also reported engine failures and power loss. ## Aircraft and maintenance information The aircraft was a two-seat, aerodynamically controlled ultralight shoulder-wing aircraft with a fixed nosewheel landing gear and a closed cabin. It was manufactured by Comco Ikarus GmbH, with serial number 9810-6141, built in 1998, and had a maximum takeoff weight of 472.5 kg. The aircraft had accumulated 2,440 flight hours and was powered by a Rotax 912 UL engine, serial number 4403055. It had first been registered in the Netherlands and was later approved for operation in Germany in 2002. The last annual inspection was performed on 19 August 2009, after which approximately 100 hours were flown. Maintenance was carried out by the owner, and no evidence of periodic inspections was found in the operational records. ## Engine and post-accident findings The engine had exceeded its manufacturer-specified time between overhauls of 1,200 hours or 15 years, whichever occurred first. Both carburettors had been pulled from their mounts but remained connected to the fuel lines. The oil filter had broken off from its mounting on the oil pump housing. The carburettors were found to be adjusted according to manufacturer specifications, and both float chambers were clean and free of water. The mechanical fuel pump tested within manufacturer pressure limits, while no functional test was performed on the electric fuel pump. The bypass line was installed without the check valve required by the engine manufacturer. Fuel pumps, fuel filters, the fire shutoff valve, and fuel lines were checked for continuity, with no damage or malfunction found. During disassembly of the ignition system, several wires to the surface-mounted device modules had been repaired by soldering with unsuitable cables, and the wire insulation on the ignition box SMD modules was worn through. The SMD modules, ignition coils with leads, spark plug caps, and spark plugs were tested and found to be functional. The cylinder heads, cylinders, and pistons showed no findings. A compression loss test recorded 40% for cylinder 1, 95% for cylinder 2, and 4% for both cylinders 3 and 4. The gearbox was removed and showed no component damage. The crankshaft stub had a runout of 0.52 mm, compared with a maximum allowable value of 0.08 mm. The crankcase was disassembled, and the crankshaft bearing locations showed no findings, while the main bearing shells had slight pressure marks consistent with a twisted crankshaft. The camshaft and camshaft bearings showed no findings. Oil and fuel samples were analysed and showed no findings. ## Medical, survival, and investigation conclusions The pilot’s autopsy identified polytrauma as the cause of death, and cardiac dysfunction was excluded as a cause of the accident. No fire occurred. The aircraft’s rescue system was not deployed. During impact, the upper and outer harness attachment points on the pilot’s seat failed, ejecting the pilot from the cockpit and causing fatal injuries. The aircraft was approved for operation in Germany, and the pilot held a valid licence and a Class 2 medical certificate. The engine’s time between overhauls had been exceeded, and maintenance records and evidence of maintenance work were incomplete. The inspection records contained no mention of the expired TBO, the repaired cables, or the worn areas in the ignition box. Compression loss in cylinders 1 and 2 was attributed to loose oil carbon particles deposited on the valve seats. Pressure marks on the crankshaft main bearing shells indicated that the crankshaft had twisted due to propeller ground contact while the engine was running. Oil analysis found no evidence of abnormal wear or mechanical damage, and fuel analysis excluded power loss caused by contamination or mixing with other fuels. No trigger for engine stoppage or power loss was identified during disassembly, although an engine malfunction with power loss could not be excluded based on witness statements and the general condition of the engine. The accident was attributed to the aircraft falling below minimum flight speed at low altitude during climb, with engine power loss during climb not excluded.