What happened
On November 23, 2009, an EMB-720D, registration PT-VIF, was conducting a flight from Catanduva, SP, to a private landing site in Mato Grosso. After a technical stop in Rondonópolis for refueling, the aircraft was cruising at 4,500 feet when the pilot reported engine vibrations, RPM fluctuations, and a loss of power.
In an attempt to manage the situation, the pilot followed emergency procedures, including switching fuel tanks and activating the electric fuel pump, which partially restored power. However, as a precaution, the pilot decided to land at an unregistered grass strip near the flight path. During the landing roll on the wet and slippery grass, the pilot was unable to maintain control within the strip's boundaries, resulting in a collision with a wooden and wire fence at the end of the landing area. The aircraft sustained severe damage to the propeller, wings, landing gear, and empennage, but the pilot and two passengers escaped without injury.
The investigation
CENIPA investigators examined the aircraft's mechanical condition and the operational circumstances of the landing. While an initial engine inspection found no obvious discrepancies, subsequent bench tests of the fuel system revealed that the diaphragm shaft of the fuel distributor valve was stuck, significantly restricting fuel flow to the nozzles.
The investigation also analyzed the landing site, noting that the strip was not registered in the civil aviation system and lacked a safety overrun area. Investigators also noted a discrepancy in the pilot's timeline, as the location of the landing was much further from the intended destination than the pilot's reported flight duration suggested. Additionally, the investigation looked into the maintenance history, noting the aircraft had been stationary for 32 days without following Lycoming engine preservation procedures.
Findings
- A restricted fuel flow caused by a stuck diaphragm shaft in the fuel distributor valve contributed to the engine power loss.
- The decision to land on an unregistered, non-homologated airstrip increased operational risk.
- The presence of wet, slippery grass and the use of a higher approach speed (due to partial flap deployment) likely led to hydroplaning, making the brakes ineffective.
- The lack of a safety overrun area at the landing site allowed the collision with the fence to occur.