What happened
On April 17, 2010, a Britten-Norman Islander BN-2A-9, registration PT-FBU, was performing a transport flight for FUNAI in the Brazilian state of Roraima. After an initial successful leg from Boa Vista to Aldeia Maturuca, the aircraft prepared for a return flight in the afternoon.
During the departure from the village, the pilot was unable to achieve a positive climb. Approximately 25 minutes into the flight, the left engine failed. Unable to maintain level flight on a single engine, the pilot performed a precautionary emergency landing on a road near Alde and Lago Grande. During the landing, the left main gear struck a rock, causing damage to the brake line. All 6 occupants (the pilot and five passengers) were uninjured.
The investigation
CENIPA investigators established that the left engine failure was caused by fuel exhaustion. Upon inspection, the left wing tank was found to be empty, while the right wing and tip tanks still contained fuel. No leaks were found in the fuel system.
Investigators noted that the aircraft's fuel quantity indication system was unreliable, often providing inaccurate readings. To compensate, the crew had been using a non-approved, handmade wooden ruler to manually measure fuel levels. While the pilot had checked the fuel levels during the morning departure, he did not perform a manual verification before the afternoon departure, relying instead on his earlier check.
Findings
- Fuel exhaustion in the left wing tank was the primary cause of the engine failure.
- The pilot failed to verify the actual fuel quantity before the afternoon departure.
- The aircraft was being operated with an unreliable fuel gauge, and the crew utilized an improvised wooden ruler for measurement, which was not approved by the manufacturer.
- There was inadequate operational oversight, as the operator was aware that pilots were using improvised measuring tools due to the faulty instrumentation.