What happened
On May 9, 2011, a Beech 90 King Air, registered F-GFDJ, was performing a flight that was interrupted by a mechanical issue shortly after takeoff. The pilot reported hearing a heavy thud originating from the nose gear area. Following consultation with company operations, the pilot diverted to the Auxerre Branches aerodrome.
Upon arrival, the pilot performed a low-altitude pass, during which an AFIS controller informed the crew that the nose gear appeared to be in an intermediate position. The pilot proceeded to land on the paved runway 01. During the subsequent taxiing phase, the nose gear collapsed, causing the aircraft to slide along the runway before coming to a halt. The incident resulted in substantial damage to the propellers and the forward section of the fuselage.
The investigation
The investigation focused on the mechanical integrity of the nose gear retraction/extension mechanism. Investigators examined the electric motor assembly, which drives a worm screw within a sliding unit. During the disassembly of the nose gear, investigators noted significant torsional resistance accompanied by a loud metallic grinding noise.
Detailed examination of the actuator revealed that the internal threading of the component had almost entirely disappeared, with fragments of thread found during cleaning. Furthermore, the pivot points between the main assembly and the nose gear strut showed signs of ovalization, likely caused by excessive play between the worm screw and the housing. Additionally, investigators discovered a large accumulation of highly compacted, rigid grease inside the assembly, which had lost its lubricating properties.