What happened
Prior to the accident flight, the crew conducted an engine-run test that revealed backfiring from the left engine. The captain initially suspected fuel water contamination before concluding the issue was caused by fouled spark plugs. Following a second engine run that showed no further backfiring, the crew proceeded with the cargo flight without requesting or performing any maintenance on the left engine.
During the subsequent flight, the left engine backfired again while the aircraft was approaching its destination. The flight landed without incident, and the cargo was unloaded; however, no maintenance was addressed regarding the engine issue following this arrival.
On the flight involving the accident, the first officer served as the pilot flying while the captain acted as the pilot monitoring. During the takeoff phase, the local controller observed black smoke trailing the left engine and alerted the crew. The captain dismissed the smoke as normal for the aircraft type and elected to continue the departure. As the aircraft progressed, the controller witnessed bright orange and red flames emerging from behind the left engine and alerted San Juan CERAP, who then notified the crew.
Upon receiving the alert, the captain took control of the aircraft and instructed the first officer to inspect the engine from the cabin. The first officer confirmed the presence of fire, prompting the crew to execute the fire checklist and shut down the left engine. Despite these efforts, the fire persisted because it was positioned in an area inaccessible to the fire suppression bottles.
The crew returned to the airport, where emergency vehicles were positioned along the runway. Although the aircraft landed on the runway centerline, the fire had caused damage to the left brake line. This resulted in asymmetrical braking, causing the aircraft to veer off the right side of the runway and stop near the airport perimeter fence. No fatalities or injuries were reported.
Findings
- The crew operated the aircraft without performing maintenance after observing engine backfiring on previous flights.
- The fire was located in a position that prevented the fire suppression bottles from effectively extinguishing the flames.