Incident Overview
The aircraft experienced a fire warning during its first flight of the day following engine fuel system maintenance. While climbing through 7,500 feet, the fire warning system activated, prompting the flight crew to extinguish the fire, secure the engine, and return to the departure airport.
Examination Findings
Post-flight inspection of the engine revealed a fuel leak at the #7 and #8 fuel manifold nozzle transfer tubes. The locking plates for these nozzle assemblies were found to be improperly installed, and the corresponding O-rings were cut and scratched. Additionally, the engine's overboard fuel/oil drain line was approximately 99% blocked with a carbon-like material.
Drain System Irregularities
The engine's fuel manifold and turbine support case drain lines were positioned directly opposite each other within the drain manifold. The drain line's turbine support case fitting had an oversized and offset crush gasket. Inside the nacelle, a flame discolored area was observed directly below this fitting.