Incident Overview
During normal cruise operations, the left engine experienced a 20% loss of torque. The crew was informed by company maintenance personnel that a possible fuel nozzle leak on that engine might be occurring. Subsequently, the #1 engine fire warning light illuminated and the fire horn activated. The captain secured the engine and discharged the #1 fire suppression agent. Immediately following the discharge, the associated warning lights on the fire handle and condition lever extinguished. An uneventful single-engine landing was completed, and the passengers deplaned without further incident.
Investigation Findings
Evidence of thermal damage was found in the aft section of the engine in the area of the lower turbine support case. Examination of the fuel system revealed that 3 of the 144 'O' rings associated with the 14-nozzle fuel system were deteriorated or damaged. Additionally, during testing at the engine manufacturer's facility, it was discovered that the inside diameter of the copper gasket used at the fuel drain nipple was 30 to 40% larger than required. This resulted in misalignment and a leak at the fitting.