What happened
On April 12, 2009, an EMB 720D, registration PT-VNB, was performing a local flight between Goiânia and Trindade, Goiás, when the engine began to lose power approximately 10 minutes after takeoff. The pilot attempted several corrective actions, including activating the electric fuel pump and switching fuel tanks, but was unable to restore power.
To avoid an isolated tree, the pilot performed a low-speed maneuver that resulted in a heavy impact with the terrain at Fazenda Três Furnas. The aircraft sustained severe damage to the propeller, left landing gear, left wing, aileron, and flap, while the fuselage suffered minor damage. The pilot and one passenger escaped the accident uninjured.
The investigation
CENIPA investigators discovered that while the left tank contained 104 liters of fuel, the right tank—which was selected for the flight—contained only 0.5 liters. The investigation focused on why the pilot believed the right tank was nearly full.
Technical inquiries with the manufacturer, Embraer, revealed that electrical grounding issues in the fuel sensor units could cause the fuel gauge to indicate a "full scale" reading, which can be easily mistaken for a full tank. Furthermore, the investigation found that the pilot did not wait the required 10 seconds after switching to the left tank to allow the fuel lines to prime, a critical step for restoring power after fuel exhaustion.
Findings
- Fuel exhaustion in the right tank was the primary cause of the engine failure.
- An erroneous fuel gauge reading occurred due to a potential electrical grounding failure in the sensor units, causing the gauge to indicate a full tank when it was nearly empty.
- The pilot failed to notice that the fuel level was not visually apparent during the pre-flight drainage check.
- A deviation from the pilot's routine refueling practice meant the aircraft had not been topped off after the previous trip.
- The pilot did not allow the necessary 10-second interval for fuel lines to fill after switching the fuel selector to the left tank.
Safety action
- Embraer has updated the Emergency Checklist for the EMB 720D to explicitly instruct pilots to wait at least 10 seconds after a tank switch during an engine failure to allow for line priming.
- CENIPA recommended the dissemination of this accident to operators and pilots to emphasize the importance of cross-checking fuel gauges with physical fuel levels and following proper procedures during fuel-related engine failures.