What happened
On June 13, 2018, a Cessna 150G, registration CP-815, operated by CIAC Alas Beni Flight Training Center, was conducting a local flight training mission near Cochabamba, Bolivia. The aircraft departed from runway 22 at Jorge Wilstermann International Airport at 10:23 local time, carrying an instructor and a student pilot.
While cruising at 12,000 feet, the crew experienced intense vibrations that lasted approximately ninety seconds. During this period, the engine became completely detached from the airframe. The separation caused the engine cowling to shift forward against the windshield, severely obstructing the view from the left side of the cockpit.
The instructor performed an emergency landing on a dirt path in the Buena Vista area. During the final approach, the instructor had to execute a sudden climb to avoid hitting a public transport vehicle (trufi) that was in the aircraft's path. Although the main landing gear lightly struck the roof of the vehicle without causing damage to it, the aircraft subsequently impacted the ground. The impact caused the nose gear to detach and resulted in the aircraft flipping over (capotage). Both occupants evacuated the aircraft on their own and sustained no injuries.
The investigation
The Bolivian AIG unit conducted a field investigation, locating the engine approximately 5.5 kilometers from the wreckage. Investigators examined the airframe, noting significant damage to the engine mounts, fuselage, and landing gear. An inspection of the propeller revealed that one of the blades had fractured. The investigation also noted that while the aircraft was within its weight and balance limits and had a valid airworthiness certificate, the engine and propeller components had significantly exceeded their recommended time between overhaul (TBO) intervals.
Findings
- The probable cause of the accident was an apparent fracture of one of the propeller blades, which induced severe vibrations that eventually caused the engine to detach from its mounts and supports.
- A contributing factor was the owner's failure to perform adequate non-destructive testing (NDT) on components as recommended by the manufacturer.
- The engine and propeller had accumulated over 2,293 hours of total time since new, far exceeding the recommended TBO of approximately 100 hours.