What happened
On October 31, 2010, a Piper PA-31, registration PT-DBM, was conducting an aerial surveying mission over the Trombetas River region in Oriximiná, Pará. The flight, operated by Engefoto Engenharia e Aerolevantamentos S.A., departed from Oriximiná Aerodrome at 11:10 UTC.
During the flight, the left engine suddenly stopped without prior warning. Approximately twelve minutes later, the right engine also failed. The pilot notified the Amazon Area Control Center (ACC-AZ) that an emergency landing was necessary due to fuel exhaustion. The aircraft subsequently performed an emergency landing in Erepecu Lake, on the banks of the Trombetas River. The impact occurred in a muddy area, causing the aircraft to sink nose-first, with the fuselage partially submerged up to the wing leading edges. The crew, consisting of the pilot and a special equipment operator, sustained minor injuries.
The investigation
CENIPA's investigation focused on determining why the engines failed despite the pilot's belief that the aircraft had sufficient fuel. The investigation analyzed the aircraft's fuel consumption during various flight phases, including the 25-minute period on the ground with engines running, the climb, and the cruise phase.
Investigators calculated that the total usable fuel in the Piper PA-31 was approximately 186.6 US gallons. By accounting for the consumption during the ground run, climb, and cruise at 75% power, the investigators determined that the fuel reserves had been depleted. The investigation also reviewed the operator's fueling practices, noting that the company performed its own refueling without formal fuel vouchers, making precise tracking difficult. The investigation confirmed there were no mechanical failures in the engine systems or the aircraft's fuel systems.
Findings
- Fuel exhaustion was the direct cause of the engine failures.
- The pilot reached an erroneous conclusion regarding the aircraft's endurance, overestimating the remaining flight time.
- The flight planning process was inadequate, as it failed to include the required minimum fuel reserves for abandoning the area or reaching an alternative aerodrome, as mandated by ICA 100-12.
- The aircraft sustained severe damage to the forward fuselage, engines, and propellers.