What happened
On 30 November 2018, a Cessna 310-R, registration EC-EQK, was conducting a local training flight at Cuatro Vientos Airport. The flight was intended to familiarize one of the pilots with the aircraft's handling. After approximately 35 minutes of flight, the crew executed a touch-and-go maneuver.
Upon reaching an altitude of 700 feet, the pilot attempted to retract the landing gear. Approximately 25 seconds after initiating the retraction, the crew heard a loud mechanical noise and detected the smell of smoke. Using an onboard mirror, the pilot observed that the nose landing gear leg had failed to fully retract. The crew attempted to operate the gear both electrically via the standard procedure and manually using the emergency crank, but the mechanism remained immobile. After declaring an emergency, the pilot performed a landing at Cuatro Vientos Airport using only the main landing gear. The impact caused significant damage to the propellers and the underside of the fuselage.
The investigation
The investigation focused on the mechanical failure of the nose gear extension and retraction system. Investigators examined the drive tubes and the electric motor responsible for the gear's movement. The analysis of the broken drive tube revealed no evidence of corrosion or fatigue, but rather an instantaneous overload along its longitudinal axis.
Investigators also reviewed the operation of the electric motor. It was determined that the motor's operating time exceeded its intended duty cycle because the up-limit switch never activated due to the mechanical obstruction. The burning odor reported by the crew was attributed to the electric motor overheating after being forced to run beyond its design parameters.