What happened
On April 30, 2014, at 18:33 UTC, an Alpi Aviation Pioneer 30 and registration CS-UOV departed from runway 01 of Évora Airfield (LPEV) for a local leisure flight. The aircraft was operated by a private owner and carried two pilots on board.
At approximately 18:49 UTC, the aircraft performed a low pass over runway 19 and proceeded to execute a hammerhead, an aerobatic maneuver. During the vertical climb phase of the maneuver, the engine failed. The aircraft entered a stall at a low altitude, leaving the crew with insufficient height to recover. The aircraft subsequently crashed a short distance from the end of runway 19, resulting in two fatalities and the total destruction of the aircraft.
The investigation
The GPIAA investigation examined the wreckage, engine components, and onboard video footage. Investigators analyzed the aircraft's maintenance records, which showed the plane was airworthy and compliant with its maintenance program. The investigation also reviewed the pilot's credentials, noting that while the left pilot was qualified, he lacked a valid medical certificate at the time of the flight.
Technical analysis focused on the engine failure. Investigators evaluated several possibilities, including a mechanical engine failure, an air inlet obstruction, or a fuel system failure. Additionally, the investigation reviewed footage from an iPhone 4 located on board, which captured the aircraft in an uncontrolled state during the stall. Witnesses also provided information regarding the aircraft's fueling, noting the crew had used a jerry can to refuel immediately prior to departure.
Findings
- The primary cause of the accident was an engine failure at low altitude induced by a low-G condition.
- The crew was performing a prohibited aerobatic maneuver that was not authorized by the manufacturer.
- The engine failure occurred during the final stage of the vertical climb while the aircraft was at low airspeed.
- The aircraft was in an airworthy condition and had been properly maintained.
- The left pilot was operating without a valid medical certificate.
Safety action
- The GPIAA recommended that the National Civil Aviation Authority (ANAC) take measures to ensure ultra-light aircraft owners and operators comply with regulatory requirements and manufacturer operating manuals.
- The GPIAA recommended that ultra-light pilot associations (APAU) alert members to the dangers of performing maneuvers that can cause operational failures in components like carburetors and fuel pumps.