What happened
On March 21, 2022, a PA-28-140 aircraft, registration PT-BOK, was conducting a local instructional flight near Bragança Paulista, São Paulo. Approximately ten minutes after takeoff from Arthur Siqueira State Aerodrome, the aircraft's engine experienced a sudden loss of performance accompanied by intense vibrations. The crew, consisting of a flight instructor and a pilot under supervision, performed an emergency landing in an open area within a private gated community. The impact resulted in serious injuries to both crewmembers and caused substantial damage to the aircraft's landing gear, fuselage, wings, engine, and windshield.
The investigation
CENIPA investigators determined that one of the propeller blades fractured during flight, with the fracture surface exhibiting characteristics typical of fatigue. The investigation revealed that the fatigue process was likely initiated by a dent in the propeller blade, which acted as a stress concentrator.
Significant discrepancies were found in the aircraft's maintenance records. The logbooks for the airframe, engine, and propeller were not up to date, with some records missing monthly usage entries for extended periods. Investigators noted that the propeller had been transferred from another aircraft, PT-DCW, to PT-BOK in December 2021, but there were no documented inspections of the propeller at the time of installation. Furthermore, a 50-hour inspection of the propeller had not been executed. The investigation also found that the aircraft had recently undergone a painting service performed by an uncertified professional without proper oversight, and the aircraft had not been re-weighed to update its weight and balance following this procedure.
Findings
- A propeller blade fracture caused severe engine vibration and performance loss.
- A dent in the propeller blade acted as a stress concentrator, facilitating the fatigue fracture.
- Maintenance logbooks for the airframe, engine, and propeller were outdated.
- There was a lack of documented inspection for the propeller upon its installation on PT-BOK.
- At least one required 50-hour propeller inspection was not performed.
- The aircraft's weight and balance information was unreliable following an uncertified painting process.
- Maintenance management failures led to unreliable documentation and inadequate oversight of inspections.