What happened
The aircraft performed a landing with its landing gear in the retracted position. Following the incident, once the aircraft was raised from the runway, the crew utilized the manual extension system to extend the gear.
The investigation
Post-accident investigators discovered that the circuit breaker for the gear motor had popped. A detailed examination of the landing gear system revealed that the gear motor was binding. This binding was caused by an insufficient adjustment between the transmission and the gear motor. The aircraft had recently undergone maintenance on the gear system, which included a replacement of the landing gear transmission.
Findings
Investigation determined that the mechanical binding prevented electrical actuation of the gear. It was noted that this aircraft is equipped with a manual extension system that also functions as a secondary indicator for gear position; when the gear moves via electrical actuation, the manual extension system moves simultaneously.