What happened
On November 21, 2007, an EMB-202 aircraft, registration PT-UPY, was performing its seventh load of an agricultural pesticide application flight near Ponta Porã, Mato Grosso do Sul. Shortly after takeoff, at an altitude of approximately 100 feet, the pilot attempted to adjust the power, propeller pitch, and mixture settings when the engine lost power.
To avoid a more serious accident, the pilot executed a forced landing into a nearby plowed field. The impact caused severe damage to the aircraft's landing gear, fuselage, and propeller. The pilot emerged from the wreckage uninjured.
The investigation
CENIPA investigators examined the wreckage and the mechanical components of the engine. Laboratory tests conducted on a test bench revealed that the mechanical fuel pump was failing to generate sufficient pressure to supply the engine. Upon disassembly, investigators discovered that the central shaft of the pump had detached from the drive lever. This failure was attributed to a fatigue process occurring after approximately 30,000 cycles.
The investigation also focused on the operational status of the auxiliary electric fuel pump. While the aircraft's operating manual prescribes that the electric pump must remain active during agricultural operations, the investigation found that the pilot had turned the pump off shortly after takeoff. Had the electric pump been operational, it would have maintained the necessary fuel supply to the engine following the mechanical pump's failure.
Findings
- The primary cause of the engine failure was the rupture of the mechanical fuel pump's central shaft due to fatigue.
- A contributing human factor was the pilot's decision to turn off the auxiliary electric fuel pump to prevent perceived wear, a practice common in the agricultural aviation culture despite manual requirements.
- A contributing material factor involved the design/maintenance of the mechanical pump, which led to a subsequent Airworthiness Directive (DA Nº 2008-04-01) establishing a 500-hour life limit for replacement.