What happened
On November 12, 2009, a Piper PA-30, registration PT-BKI, was performing a private flight from Belo Horizonte (SBBH) to Salvador (SBSV). The aircraft was being ferried to the headquarters of a flight school. Approximately two hours into the flight, the pilot experienced power fluctuations in the left engine, followed shortly by similar fluctuations in the right engine.
In response to the engine instability, the pilot executed the emergency procedures outlined in the aircraft's checklist and coordinated with Recife Area Control Center (ACC-RE) for an emergency landing at Almenara Airport (SNAR) in Minas Gerais. During the emergency descent, the pilot switched the fuel source from the external tanks to the main internal tanks, which stabilized the engines. The aircraft landed safely without damage, and both the pilot and the passenger were uninjured.
The investigation
CENIPA investigators examined the aircraft's fuel system and the pilot's recent flight history. Ground tests conducted by mechanics and the pilot showed that the fuel selectors and indicators were functioning normally. However, investigators discovered that while the internal tanks contained fuel, the external wing tanks and tip tanks were completely empty.
Calculations indicated that based on the flight time of 2 hours and 10 minutes and the estimated fuel consumption, the external and tip tanks should not have been depleted. The investigation noted that the aircraft's fuel selector valves only featured positions for main and external tanks, lacking a specific indicator for the tip tanks. Furthermore, the investigation found that the pilot had not flown this specific aircraft for over seven months, having only performed short-duration flights in the preceding period.
Findings
- The primary cause of the engine power fluctuations was related to inadequate fuel management or insufficient fueling of the auxiliary tanks.
- The pilot's recent experience with this specific aircraft was limited, as the previous flight in the PT-BKI had occurred more than seven months prior.
- The aircraft lacked a low-fuel warning system, necessitating heightened pilot vigilance during fuel monitoring.
- The propeller Time Between Overhaul (TBO) had expired in September 2009.
- The aircraft was within weight and balance limits, and the weather conditions were favorable for flight.