What happened
On November 3, 2022, an Aerocommander S2R, registration HK5172, was conducting agricultural spraying operations over banana crops near the Orihueca airstrip in the Zona Bananera municipality, Magdalena. After successfully completing two flight segments, the aircraft was performing its third mission at an altitude of approximately 150 feet when the pilot heard an unusual noise followed by a sudden loss of engine power.
Recognizing the emergency, the pilot leveled the aircraft and established a glide speed to locate a suitable landing site. During the final approach to an unprepared field, the pilot identified overhead electrical cables and elected to fly beneath them due to insufficient airspeed and power to climb. While maneuvering, the aircraft's left wing struck a wooden shed, causing a sharp change in trajectory. The aircraft subsequently struck the ground, skidded, and overturned, coming to rest in an inverted position. The pilot, who was the sole occupant, was able to shut off the electrical and fuel systems and egress the aircraft uninjured.
The investigation
The GRIAA investigation focused on the mechanical failure of the engine's air intake system. Technical examinations of the radial engine components revealed that the impeller had suffered a fracture. Metallurgical analysis of the failed stator vane identified the material as martensitic steel (AISI 403), noting a lower-than-expected content of manganese and nickel, though this was not determined to be the primary cause of the failure.
Investigators performed fractographic analysis and finite element analysis on the vane geometry. The evidence indicated that the fracture originated in the pressure zone of the stator vane. Furthermore, debris found inside the impeller disk—consisting of dolomite, basalt, sandstone, quartz, and quartzite—matched the composition of the gravel used for the surface of the Orihueca airstrip.
Findings
- The primary cause of the engine power loss was a failure in the air intake system caused by the fracture of the impeller due to an impact from a foreign object (FOD).
- The presence of large stones on the unpaved, compacted gravel runway at the Orihueca airstrip contributed to the ingestion of debris into the engine.
- The operator's Safety Management System (SMS) lacked an effective, systematic, and proactive program for the prevention of foreign object damage.
- The aircraft sustained substantial damage to the wing surfaces, cockpit structure, windshield, and propeller.