What happened
On July 3, 2006, an Embraer EMB 145 was taxiing from taxiway C to runway 09 at Saarbrücken Airport. During the turn, the left nose gear axle fractured, causing the aircraft to lose its left nose wheel. The crew did not immediately realize the wheel had detached, though they did notice metal debris lying on the threshold of runway 09.
The aircraft departed for Munich at 19:09. After takeoff, the crew reported the presence of the metal fragments. A subsequent inspection of the runway by airport authorities recovered the left nose wheel and two metal rings. The crew was notified of the findings but continued the flight to Munich. Upon arrival, a low-level inspection of runway 08 L in Munich confirmed that the remaining right nose wheel was undamaged. The aircraft landed without further incident and taxied to its parking position.
The investigation
The BFU examined the nose gear assembly, which featured a continuous axle pressed into the nose gear strut. The nose wheels were held in place by a castle nut on the axle, with bearing play adjusted via the nut's torque. The investigation included a metallurgical analysis of the fracture site conducted at the Institute for Materials at the Technical University of Braunschweig.
Using scanning electron microscopy, investigators examined the fracture surface. The analysis revealed a topography of micro-ductile honeycombs, which is characteristic of a brittle fracture. The examination confirmed that the axle had not been previously weakened by fatigue cracks or corrosion; the fracture surface showed evidence of a single-event overload.