What happened
On September 6, 2002, an EMB 710C, registration PT-NCX, was operating a VFR flight from Belém (SBJC) to Altamira (SBHT) with one pilot and three passengers. The day began with an aborted takeoff attempt due to an engine failure where a spark plug was expelled from the engine. Following this, an improvised repair was performed using a brass bushing to secure the spark plug, a service carried out by an unauthorized mechanic.
During the second takeoff attempt later that morning, the engine experienced a similar failure when the newly installed bushing was again expelled, leading to a loss of power. The pilot attempted to maintain altitude and execute a wide turn to return to the runway. During this maneuver, the aircraft lost lift and struck a tree before impacting the ground. The impact caused the aircraft to break apart and catch fire. The pilot and one passenger were killed, while the remaining two passengers sustained serious injuries.
The investigation
CENIPA's investigation focused on the mechanical failure and the circumstances leading to the flight. Technical analysis by the CTA (Centro Técnico Aeroespacial) revealed that the improvised brass bushing failed because the cylinder threads had worn down due to fatigue cracks. These cracks were caused by a poorly angled hole drilled for a cotter pin, which acted as a stress concentrator.
The investigation also identified that the aircraft was operating in an overweight condition, as it was carrying two fuel containers in the baggage compartment that shifted the center of gravity behind the allowable limit. Furthermore, investigators found that the pilot was using medication that was contraindicated for flight operations, and the maintenance performed was not recognized as appropriate for aviation standards.
Findings
- Improper maintenance performed by an unauthorized individual was the decisive factor in the accident.
- The use of an unapproved brass bushing and an improper drilling technique led to the engine component failure.
- The aircraft was overweight and improperly loaded, with fuel containers shifting the center of gravity.
- The pilot's decision-making was compromised by high levels of anxiety, overconfidence, and the use of contraindicated medication.
- There was a lack of proper supervision regarding the unauthorized maintenance work performed at the hangar.
- The airport's emergency response was delayed because a locked gate prevented fire trucks from accessing the crash site via the most direct route.