N375HA

SUMMARY

On November 7, 2017 at approximately 9:00 PM Pacific Daylight Time a Hawaiian Airlines Airbus A330-243 airplane, Registration Number N375HA, flight 8075, sustained a control issue of the left-hand (LH) Rolls Royce (R-R) Trent 700 turbofan engine resulting in pulses of flame from the aft of the engine just after landing on runway16L at Seattle-Tacoma International Airport (SEA). After touchdown, the engine emitted sufficient liquid fuel and flames from the exhaust to cause thermal damage to the nacelle, pylon, wing, and flaps. The repositioning flight originated at Paine Field (PAE), Washington and was on a ferry flight after having interior upgrades installed, a 10-day job, and was enroute to Seattle, Washington, to begin regular service. No engine work was carried out during this period.

There were two crew and no passengers on board. It was reported that the pilot was unaware of the fire and was informed of the condition 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; however, the fire was extinguished before they arrived.

During an initial inspection, the maintenance staff discovered fire distress on the engine common nozzle assembly, underside of the wing, pylon, flap track fairings, spoilers, and flaps. The initial examination of the incident airplane and engine occurred between November 9 to 12, 2017 at the Seattle-Tacoma Airport.

The engine was shipped to a Rolls-Royce Trent overhaul facility, N3 Engine Overhaul Services (N3EOS) GmbH in Arnstadt, Germany where the team met between December 17 and 19, 2017 to remove specific external fuel related components for detailed teardown.

DETAILS OF THE INVESTIGATION

On-Scene Examination

Engine Data Review

The engine health monitoring (EHM), the aircraft communication addressing, and reporting system (ACARS) and the aircraft condition monitoring system (ACMS) data was reviewed, and the following observations were revealed.

ESN 42543 exceedance messages:

- 05:00:17 (UTC) N2 Redline Exceedance for 3 seconds

- 05:00:32 (UTC) N2 Redline Exceedance for 7 seconds

- 05:01:15 (UTC) N2 Over Limit

- 05:02:46 (UTC) N2 Redline Exceedance for 8 seconds

- 05:03:26 (UTC) Turbine Gas Temperature (TGT) Redline Exceedance

Each exceedance was approximately 104 percent (%) N2 speed.

The following observations were made from the findings:

A comparison of the variable stator vane (VSV) positions revealed that there was a large behavior difference between the LH and RH engines.

The P30 pressures of LH and RH engines were both equal and stable; however, while the VSV positions on the RH engine corresponded to the VSV demand, the LH engine exhibited large variations and did not correspond to the VSV demand.

VSV variations directly impact N2 speed and the high angle of the LH engine VSVs directly increased the N2 to overspeed.

The fuel flow (FF) did not correspond to the engine speed increase during the overspeed events, indicating that the electronic engine control (EEC) was not commanding the overspeed.

The variation in engine pressure ratio (EPR) did not correspond to the FF variation, indicating that the FF was not the significant cause of the EPR variation.

The EEC did not stop the overspeed occurrences because its logic only intervenes above 114%.

Because of these findings, the fuel metering unit (FMU), EEC and VSV control system were examined in more detail.

Event Timeline Data Review

During descent VSV control was slow to respond and engine became increasingly unstable.

The electronic centralized aircraft monitor (ECAM) message ENG1 CTL SYS FAULT “avoid rapid thrust change” message inhibited as aircraft on final approach permitting full reverse thrust application.

Aircraft landed at - 05:01:48.

Full thrust reverse was selected at - 05:01:51 – It is noted that during reverse thrust operation, the EEC logic controls in N1 mode. The VSV system did not respond to engine power selection, and FF increased to maximum output at about 31,600 pph to achieve the demanded N1 speed. This would indicate that flames from the engine tailpipe had not occurred until after the aircraft had landed.

Little or no response from VSV system to commanded thrust resulted in restriction to core airflow and suppression of N1 speed.

Simultaneously the resultant N3/P30 mismatch triggered P30 pipe failure detection, which inhibited the engine surge detection function.

The EEC commanded an increased FF to maximum of about 32K pph in an attempt to achieve the demanded N1, incorrect VSV position resulted in engine surge - 05:01:56.

Unburnt fuel continued to ignite at and behind the engine tail pipe.

Thrust reverse cancelled and EEC logic changed engine governance from N1 to N3 control - 05:02:14.

At this point N3 speed, which was within the specified EEC synthesized levels, stagnated at about 67%, and the control system logic maintained the high FF delivery.

The engine continued to surge, and the airport closed circuit TV (CCTV) footage indicated that unburnt fuel continued to ignite to the rear of the engine tail pipe.

TGT exceeded 900°C and EEC reduced the FF at 05:02:43.

FF demand was only reduced when the EEC detected an engine TGT exceedance, and shortly afterwards the flight crew shut the engine down.

Pilot made aware of tail pipe fire by ATC and engine was shut down using the fire handle (aircraft low pressure spar valve closes) - 05:02:46.

Engine master lever selected “off” and engine shutdown - 05:02:47.

Analysis of the VSV positional data taken from the N2 exceedance reports observed a disagreement between the demanded and actual position of the VSVs, to a point where control was lost. Further assessment noted the VSV response time had become increasingly sluggish for each N2 exceedance.

General Airplane Examination

Initial examination of the incident airplane and engine occurred from November 9 - 12, 2017 at the Delta Airlines maintenance facilities in Seattle, Washington. Investigation team members including the NTSB, FAA, Hawaiian Airlines, UK AAIB, R-R, and ALPA were in attendance. The left-wing external composite panels on the common nozzle assembly, lower panels of the flaps, and flap track covers had evidence of burn patterns and blistered paint consistent with unburnt fuel vapors igniting towards the back of the engine

The event engine was detached, lowered from the airplane, placed on an engine stand, and moved to a secure area. The engine was externally intact and undamaged. The fan could be turned with normal effort and when turned, no grinding or other abnormal sounds could be heard emanating from the engine core. The engine pylon mount hardware was intact and undamaged. There were no leaks in any of the oil or fuel lines.

The engine was externally clean. There were no signs of mechanical or thermal distress. The fan cowls and thruster reverser cowls were undamaged and clean. The front spinner cone was undamaged and exhibited only operational erosion of the paint. The last stage of the LP turbine was undamaged. There was no obvious unusual discoloration on the LP turbine blades. The fan blades were undamaged. The fan case track liner was undamaged and showed no evidence of scoring. The fan was not further disassembled or examined.

The scavenge oil filter and LP fuel filter were removed, examined, and found to be in an unremarkable, nominal clean condition.

A borescope inspection of the entire rotating group was performed and included the LP turbine, high-pressure nozzle guide vanes, HP turbine, combustion section, HP compressor, IP compressor, and IP turbine. All rotating group components appeared to be intact and undamaged.

An external visual inspection of the VSV system found no obvious damage or distress. The VSV rams were disconnected from the unison rings to enable the independent movement of the vanes. The movement of the assembly was noted to be consistently smooth throughout the range with minimal input load.

The common nozzle assembly was intact, however; there was evidence of oily soot at several locations. There was a dislocated panel at the 2 o’clock location that displayed heat distress. The external surface showed evidence of heat distress at the 9 o’clock position consisting of light blistering and discoloration of the paint surface.

Engine Externals Examination and Findings

The engine was shipped to a Rolls-Royce Trent engine overhaul facility, N3 Engine Overhaul Services GmbH where the team met to remove external components below that were germane to the faults observed:

- Fuel metering unit (FMU)

- EEC and power control unit (PCU).

- VSV controller and the RH and LH VSV actuators

- FOHE and LP fuel filter

- Fuel Pump (an assembly, consisting of the HP and LP pumps)

- High pressure (HP) filter – 70 micron (µm)

Variable Inlet Guide Vane (VIGV) & VSV Control System Description

The variable inlet guide vanes direct air into the intermediate pressure compressor at the correct angle-of-attack to avoid compressor surge and stall while maintaining optimum engine efficiency. A single stage variable inlet guide vanes are located immediately behind the engine section stators. A further two stages of variable stator vanes are located after the first and second stages of the intermediate compressor. Two identical VSV actuators provide the power to move the VSV mechanism to the required position. Each actuator is connected to the unison rings via an adjustable bellcrank linkage. The unison rings then connect to the individual VSV airfoils via a lever arm. The actuators are powered by high-pressure (HP) fuel from the VSV actuator control valve and there are separate fuel lines to the ‘extend’ and ‘retract’ sides of the actuator. A variable stator vane control system operates the variable inlet guide vane system by receiving an electrical signal from the EEC that sets positional demand to match t...