What happened
On January 10, 2010, an ATR-72-212A, registration PP-PTO, operated by Trip Linhas Aéreas, was performing a scheduled passenger flight from Curitiba to Cascavel, Brazil. The aircraft was carrying four crew members and 57 passengers.
During the approach to Cascavel, the crew encountered heavy weather and low visibility, reaching the minimum descent altitude (MDA) without visual contact with the runway. As the crew initiated a missed approach, the engine fire warning light for the number one (left) engine activated. The crew immediately executed emergency procedures, shutting down the affected engine and discharging both fire extinguishing bottles, though there was no immediate result.
Due to the deteriorating weather conditions at Cascavel, the crew decided to divert to Foz doSB Iguaçu. During the flight to the alternate airport, the fire warning light extinguished after approximately nine minutes. The aircraft landed safely in Foz do Iguaçu; however, the landing caused the tires to overheat and lose pressure.
The investigation
CENIPA's investigation focused on the origin of the fire and the maintenance history of the engine. Investigators found that an undetermined amount of fuel had leaked from the number two fuel injector of the left engine into the engine cowling. When the aircraft's angle of attack changed during the missed approach, the fuel flowed near hot engine components, causing ignition.
The investigation revealed that the fire caused damage to the engine's external wiring, cowlings, and brackets, but no internal engine damage was found during subsequent borescope inspections. Crucially, the investigation identified that the fuel injector had been improperly installed during a recent "Weekly Check" performed on January 3, 2010. The maintenance team had failed to use the specific specialized tooling recommended by the engine manufacturer for this task.
Findings
- Improper maintenance of the number two fuel injector led to a fuel leak.
- The maintenance planning failed to provide the required specialized tooling for the injector installation.
- Maintenance supervision failed to verify the correct installation of the component before returning the engine to service.
- The physical difficulty of accessing the injector area, combined with the lack of proper tools, contributed to the incorrect installation.
- The fire was contained within the cowling, which likely prevented the fire extinguishing bottles from being immediately effective.