What happened
On September 19, 2011, a Neiva EMB-202, registration PT-URD, was conducting an agricultural spraying operation near Iaras, São Paulo. The aircraft departed from the Fazenda Rio Pardo aerodrome to apply herbicide over an orange plantation. Approximately 15 minutes into the flight, while the pilot was performing area reconnaissance, the engine experienced a sudden and significant loss of power. The pilot reported that while oil pressure and temperature remained normal, the throttle and mixture controls became unresponsive, accompanied by engine vibration.
Following emergency procedures, the pilot jettisoned the chemical load and executed a forced landing in an orange grove. The aircraft sustained substantial damage, but the pilot emerged uninjured.
The investigation
CENIPA investigators examined the engine and the fueling process at the farm. Although fuel samples taken from the wing tanks were found to be clear and free of solid particles, the engine inspection revealed significant contamination. Specifically, there was an accumulation of residue on the spark plugs and excessive deposits within the combustion chambers, spark plugs, and piston heads.
Investigators noted that the aircraft's refueling site was inadequate, with equipment stored outdoors under tarpaulins. The investigation concluded that the engine failure was likely caused by the accumulation of dust or debris during the refueling process, which could have occurred within the storage drums, the transport vehicle, or the manual jerrycans used for fueling. Additionally, it was noted that the auxiliary electric fuel pump was not active at the time of the failure; while the pilot activated it during the emergency, it was likely too late to compensate for the fuel delivery issue.
Findings
- Contamination of spark plugs and combustion chambers due to improper handling and storage of fuel.
- Inadequate refueling practices, including the use of exposed equipment and potentially contaminated containers.
- Failure to operate the auxiliary electric fuel pump according to the operational manual, which requires it to remain on during agricultural operations.
- Pilot judgment regarding the use of the auxiliary pump, influenced by a common but incorrect practice of turning it off to prevent premature wear.
- Management and supervisory failures regarding the oversight of refueling procedures.