What happened
On May 24, 2002, an Embraer E-720D, registration PT-OFA, operated by Amazonaves Táxi Aéreo Ltda, departed from the Atibaia Aerodrome in São Paulo for a local flight following a 1,000-hour inspection and weighing. Shortly after takeoff, the engine failed as the aircraft crossed the opposite end of the runway.
In an attempt to return to the departure runway, the pilot executed a right-hand turn. During this maneuver, the pilot failed to extend the flaps and allowed the airspeed to decay. The aircraft entered a stall and struck the ground with its right wing, subsequently striking a wall. The impact resulted in the complete destruction of the aircraft and caused serious injuries to the pilot.
The investigation
CENIPA investigators examined the engine's accessory gearbox and found significant mechanical failures. Specifically, the magneto gear showed six fractured teeth. The investigation revealed that the drive gear for the accessory gearbox was loose and rotating freely because its securing bolt had become unfastened. This was attributed to improper installation, likely involving an incorrect torque or a failure to properly install the lock washer.
Furthermore, investigators identified discrepancies in maintenance records. While the aircraft had undergone a major overhaul, the documentation regarding the implementation of Airworthiness Directive (AD) 9114-2/2 was inaccurate, citing the wrong bulletin number. The investigation also noted that the pilot had fueled only the right tank with 45 liters, leaving the left tank empty, which contributed to an asymmetric stall during the emergency maneuver.
Findings
- Improper maintenance of the engine accessory gearbox, specifically the failure to properly secure the drive gear bolt, which led to the engine failure.
- Inaccurate maintenance documentation regarding the application of manufacturer service bulletins and airworthiness directives.
- Poor emergency decision-making by the pilot, who attempted a return to the runway instead of performing a landing straight ahead, which is standard procedure for low-altitude engine failures.
- Improper aircraft configuration during the emergency, as the pilot failed to extend the flaps, increasing the stall speed.
- Asymmetric weight distribution due to the decision to fuel only the right wing, which exacerbated the loss of control during the turn.