What happened
On July 24, 2012, a Piper PA-31, registration PR-LDS, operated by Lasa Prospecções S.A., was conducting a specialized aerial survey flight near Rio de Janeiro, Brazil. The mission involved testing geophysical prospecting equipment over the coastline. The flight, which was planned to last approximately 1 hour and 20 minutes, significantly exceeded its intended duration, lasting roughly 2 hours and 45 minutes.
During the return leg to Jacarepaguá Aerodrome (SBJR), the aircraft's right engine failed at the 2-hour and 30-minute mark of the flight. Approximately four minutes later, the left engine also failed. The pilot performed an emergency ditching in the sea, approximately 2 NM from the Barra da Tijuca beach and 3.3 NM from the runway threshold of SBJR. The aircraft sank and was destroyed, but all 3 crew members were rescued from life rafts and remained uninjured.
The investigation
CENIPA investigators established that while the aircraft was airworthy and the crew was properly licensed, there was a significant discrepancy between the planned fuel consumption and the actual consumption experienced during the flight. The aircraft's manual specified a fuel flow of 35.6 USGAL/h during level flight, but the crew observed much higher rates of 46 USGAL/h.
Data extracted from the geophysical equipment's flight logs confirmed that the flight duration far exceeded the original flight plan. Although the initial fuel load was sufficient for the planned mission, the higher-than-expected fuel burn reduced the aircraft's total endurance. Investigators also noted that the right engine, which had a slightly higher fuel consumption rate than the left, was the first to fail.
Findings
- The actual fuel consumption during flight was significantly higher than the values specified in the aircraft manual and used in the flight planning.
- The crew was aware of the increased fuel consumption during the flight, yet the decision to proceed with the return leg was made despite insufficient fuel margins.
- Improper pilot judgment regarding fuel management and the decision-making process regarding the return flight contributed to the fuel exhaustion.
- The aircraft experienced a classic dual-engine failure sequence characteristic of fuel exhaustion, where one engine fails followed by the other due to asymmetrical consumption.