What happened
On July 10, 2024, at 15:00 UTC, a Baloo aircraft, registration LV-X226, departed from the Lago Nahuel Huapi aerodrome in San Carlos de Bariloche, Argentina, for a local flight training mission. During the initial climb phase, the pilot encountered a malfunction in the throttle command system that prevented the reduction of engine power.
In an attempt to manage the situation, the pilot switched off one of the magnetos to decrease power and initiated a return to the aerodrome. However, the power reduction was insufficient. The pilot then switched off the second magneto to stop the engine entirely. During the return maneuver, the aircraft encountered stronger winds than anticipated, and because the engine could not be restarted, the pilot was forced to perform an emergency landing in an unprepared field near the threshold of runway 30. The aircraft sustained light damage to the landing gear and the ventral area, but the pilot remained uninjured.
The investigation
The investigation focused on the mechanical integrity of the throttle system and the aircraft's recent maintenance history. The aircraft had recently returned to service following a three-year period of inactivity and had received a new experimental airworthiness certificate just one week prior to the incident. This flight was the first operation conducted under the new certificate.
Investigators examined the routing of the throttle cables from the cockpit to the engine. They analyzed the synchronizer mechanism responsible for distributing movement to the two carburetor throttles. The inspection of the wreckage and the hangar components revealed that the cables were not properly secured to the airframe and were found to be twisted and improperly routed toward the carburet_uretor pistons.
Findings
- The aircraft had been returned to service only one week before the event following a period of long-term inactivity.
- The flight was the first operation performed after the issuance of a new experimental airworthiness certificate.
- An entanglement of the throttle cables caused the synchronizer mechanism to jam in a position corresponding to maximum or near-maximum power.
- The design of the synchronizer mechanism lacked an internal guide to prevent longitudinal rotation, which likely facilitated the twisting and subsequent jamming of the control cables.