What happened
On July 18, 2002, an Aerotrike Scout, registration ZU-CLJ, was involved in a ground accident at Springs Aerodrome. During the taxi phase, a student pilot was moving the aircraft toward the runway 32 holding point using only choke. While attempting to line up on the runway, the pilot noticed the throttle pedal felt stuck after applying pressure.
Seeking to investigate the issue, the pilot attempted to return to the hangar. During this maneuver, a second application of pressure caused the throttle to release, but it subsequently jammed in the full open position. Despite the pilot's immediate attempt to shut down the engine by switching off the magneto switches, the aircraft continued to move, eventually colliding with a fence located to the left of the runway near the fuel bay area. The pilot sustained minor injuries, though the aircraft suffered substantial damage.
The investigation
The investigation focused on the mechanical failure of the throttle control and the pilot's ability to mitigate the engine's power. Investigators examined the aircraft's maintenance history and found that the aircraft had been maintained according to prescribed intervals, with only 23 hours flown since its last annual inspection.
During the post-accident review, the pilot noted that an additional complication occurred during the emergency: the left magneto switch was difficult to access and deactivate because radio cables were obstructing the controls. Meteorological data at the time of the accident indicated a temperature of –2°C.
Findings
- The primary cause of the incident was a frozen throttle cable.
- The malfunction was likely triggered by moisture entering the cable sleeve, which then froze due to the sub-zero ambient temperatures.
- The pilot's ability to shut down the engine was hindered by the physical obstruction of the magneto switches by radio cabling.