What happened
On November 8, 2004, a Piper PA3-34 operated by Fox Táxi-Aéreo departed from Monte Dourado Aerodrome (SBMD) in Pará, Brazil, bound for Júlio César (SBJC). The aircraft was performing a passenger transport flight with one pilot and three passengers on board.
Approximately 40 seconds after takeoff, while transitioning to a climb, the pilot noted an unusual noise and a loss of power. To identify the affected engine, the pilot manually adjusted the throttles alternately rather than relying on instrument readings. Upon determining that the right engine was malfunctioning, the pilot decided to immediately return to the departure runway using the opposite end of the field.
During the approach, the aircraft drifted diagonally toward the runway edge. While attempting to correct the flight path and realign with the runway centerline, the right wingtip struck the ground. This impact caused the aircraft to lose control and slide along the runway, resulting in substantial damage to the right wing, engines, propellers, and landing gear. All four occupants escaped the accident without injury.
The investigation
CENIPA investigators examined the right engine and discovered that the number 2 exhaust valve had sheared. Although this failure caused the reported noise and a power loss of approximately 30%, the investigation determined that the engine was still capable of maintaining enough power to avoid an immediate emergency landing.
The investigation also revealed discrepancies in the propeller settings. While the right engine (the failed engine) remained in flight pitch, the left engine had been set to feather. Crucially, the cockpit throttle positions were found to be inverted, suggesting the controls were manipulated after the event. This error led to the healthy engine being feathered instead of the malfunctioning one.
Findings
- The pilot's judgment of pilotage and command application were primary contributing factors.
- The pilot's decision to perform an immediate return to the runway was premature, as the aircraft could have completed a normal traffic pattern for a precautionary landing.
- The improper feathering of the left engine (the functional engine) instead of the right engine contributed to an unstable approach.
- The aircraft's approach to the runway was diagonal, leading to the excursion beyond the lateral limits of the runway and the subsequent wingtip strike.