What happened
During the landing roll, the nose landing gear collapsed after it had been lowered to the runway. At the time of the incident, the aircraft had accumulated 4 hours and 6 cycles since a progressive inspection performed two days prior.
The investigation
An FAA maintenance inspector examined the nose landing gear assembly and determined that the nose landing gear actuator was not damaged. Upon removal and disassembly of the actuator, investigators discovered that an extra packing, similar to an O-ring, had been installed. This additional component allowed the nose landing gear down and locked light to illuminate, but it caused the motor to shut off before the gear reached its full extension.
Review of the aircraft logbooks showed that during a progressive inspection two days before the accident, it was noted that the nose landing gear actuator switch was leaking. The recorded corrective action for this leak involved replacing the O-rings. According to the illustrated parts list for the nose landing gear actuator, two packings should be installed. The director of maintenance stated that the mechanic performing the replacement was provided with two new packings but only removed one existing packing from the actuator, which resulted in the extra packing being present.