What happened
On January 8, 2013, a Cessna 172M, registration TG-FKK, experienced a catastrophic metallurgical failure of its propeller while in flight. A section of one propeller blade, approximately 30 centimeters in length, fractured and detached from the hub. This loss of mass created an immediate and massive imbalance, resulting in intense, continuous vibrations throughout the aircraft. These vibrations caused significant damage to the engine and the airframe.
The pilot declared an emergency with Aurora Air Traffic Control, reporting the situation via the established frequency. Despite the severe mechanical distress, the pilot successfully managed the emergency and landed the aircraft on the runway at La Aurora International Airport. There were no fatalities and no injuries were reported among the pilot or the passengers, all of whom evacuated the aircraft on their own.
The investigation
The DGAC/UIA investigation focused on the mechanical failure of the propeller and the maintenance history of the aircraft. Investigators examined the propeller, a Sensenich model, and found that it lacked proper traceability documentation regarding its installation on January 31, 2012. Furthermore, the records did not provide consistent information regarding the total hours of operation for the component.
The investigation also scrutinized the maintenance organization (OMA) responsible for the propeller's last service. It was established that the facility (DGAC/G-017-2008) did not possess the specific authorization required to perform the necessary overhaul or inspection for that particular propeller brand. Additionally, the aircraft's maintenance logs showed that while the aircraft was within its scheduled service interval, the propeller's service history was incomplete.
Findings
- The primary cause of the accident was improper maintenance practices regarding the propeller.
- A metallurgical fracture in the propeller blade caused the severe imbalance and subsequent vibration.
- The maintenance organization that performed the propeller service lacked the proper certification/authorization for that specific component type.
- There was a lack of traceability and documented service life for the propeller component.
- The intense vibrations caused significant, potentially hidden, structural damage to the engine and fuselage.