Incident Overview
On November 7, 2017, at approximately 9:00 PM Pacific Daylight Time, a Hawaiian Airlines Airbus A330-243 (registration N375HA) operating as flight 8075 sustained a control issue with the left-hand Rolls-Royce Trent 700 turbofan engine after landing on runway 16L at Seattle-Tacoma International Airport (SEA). The repositioning flight originated from Paine Field (PAE), Washington, and was en route to Seattle to begin regular service after interior upgrades. There were two crew members and no passengers on board. The pilot was unaware of the fire and was informed by the control tower. The first officer shut down the left engine using the engine fire switch and discharged one fire bottle. Seattle aircraft rescue and firefighting (ARFF) responded, but the fire was extinguished before their arrival.
Investigation Findings
Examination of engine data revealed multiple N2 redline exceedances and a turbine gas temperature exceedance. The variable stator vane (VSV) positions on the left engine exhibited large variations and did not correspond to VSV demand, directly increasing N2 to overspeed. The fuel flow did not correspond to engine speed increase during overspeed events, indicating the electronic engine control (EEC) was not commanding the overspeed. The EEC did not stop overspeed occurrences because its logic only intervenes above 114% N2.
During descent, VSV control was slow to respond, and the engine became unstable. After landing, full reverse thrust was selected, but the VSV system did not respond, leading to an engine surge and unburnt fuel igniting at the tailpipe. The engine continued to surge until the EEC reduced fuel flow after detecting a TGT exceedance. The flight crew shut down the engine shortly thereafter.
Engine and Component Examination
The engine was shipped to N3 Engine Overhaul Services GmbH in Arnstadt, Germany, for detailed teardown. The fuel metering unit (FMU) showed no internal damage. The EEC fault store recorded a slow VSV torque motor response. The VSV controller's torque motor supply port filter was found 95% blocked with contamination consisting of metallic elements and fuel breakdown products. The main inlet filter (45µ) was remarkably clean, suggesting free water in the system may have caused a sudden blockage of the downstream filter. The left and right VSV actuators were contaminated with aluminum sulphate (alum), indicating free water presence. The low-pressure fuel filter also contained alum. The fuel pump assembly showed abnormal cavitation erosion in the high-pressure stage.
Summary of Findings
The investigation determined that the VSV controller torque motor supply port filter was 95% blocked, restricting fuel flow and slowing VSV actuator response, leading to loss of VSV control and engine surges. The presence of alum and free water in the fuel system was noted, but the source of the alum could not be determined.