What happened
On September 15, 2009, at approximately 20:54 UTC, a PA34-220T Seneca V, registration OO-TML, operated by the Academia Aeronáutica de Évora, experienced a catastrophic structural failure during a night navigation flight. The aircraft was performing a training mission from Seville to Évora, climbing to 8,000 feet, when it suddenly disappeared from radar near XAPAS. The aircraft subsequently crashed into an agricultural field near the village of Sete, in the Castro Verde municipality.
The flight crew, consisting of one flight instructor and two student pilots, all perished in the accident. The aircraft was destroyed by the forces of impact and in-flight disintegration.
The investigation
The GPIAAF investigation focused on the sequence of events leading to the loss of control and the subsequent structural failure. Investigators examined the aircraft's flight history, the training curriculum of the operator, and the mechanical condition of the engine and flight controls. Technical analysis included an inspection of the engine components, such as the crankshaft main bearings, connecting rods, and the turbocharger, as well as the flight control system.
Findings
- The primary cause of the accident was a runaway trim event that was not adequately resolved by the crew.
- This uncontrolled trim movement led to a loss of aircraft control, subjecting the airframe to aerodynamic loads that exceeded its structural design limits, resulting in in-flight disintegration.
- The flight instructor's lack of training in recovering from abnormal attitudes was a significant contributing factor.
- The lack of external visual references due to the nighttime conditions exacerbated the difficulty of recovering the aircraft.
- At the time of the accident, the operator's training program did not include instruction for recovering from abnormal attitudes using visual or instrument references, nor was such training mandated by the National Civil Aviation Authority.
- Engine inspections revealed that while the engine components (bearings, rods, and camshaft) were in good operating condition, the turbocharger and wastegate sustained impact damage consistent with the crash.