Qantas A333 at Sydney on Jun 1st 2018, engine shut down in flight

Last Update: August 28, 2020 / 10:18:49 GMT/Zulu time

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Photo of Qantas VH-QPI, Airbus A330-300 — Qantas VH-QPI, Airbus A330-300 (Photo credit: ATom.UK / Flickr / License: CC by-sa)

Incident Facts

Date of incident
Jun 1, 2018

Classification
Incident

Cause
Engine shut down in flight

Airline
Qantas

Flight number
QF-23

Departure
Sydney, Australia

Destination
Bangkok, Thailand

Aircraft Registration
VH-QPI

Aircraft Type
Airbus A330-300

ICAO Type Designator
A333

A Qantas Airbus A330-300, registration VH-QPI performing flight QF-23 from Sydney,NS (Australia) to Bangkok (Thailand) with 297 passengers and 13 crew, was in the initial climb out Sydney's runway 16R when the crew stopped the climb at about 7000 feet reporting an engine (CF6) issue. The aircraft entered a hold for about 40 minutes while the crew was working the related checklists and burned off fuel and the airport performed a runway inspection without finding any debris on the runway. The aircraft landed safely back on Sydney's runway 16R about 55 minutes after departure.

The airline reported the aircraft returned to Sydney about one hour after departure due to an engine issue.

A replacement A330-300 registration VH-QPH is estimated to reach Bangkok with a delay of about 6 hours.

The occurrence aircraft is still on the ground in Sydney 12 hours after landing back.

On Jun 6th 2018 the ATSB reported the aicraft was in the initial climb when the crew observed abnormal engine and airframe vibrations along with abnormal engine indications for the right hand engine. The crew stopped the climb at 7000 feet, shut the engine down and returned to Sydney for a safe landing. The ATSB opened an investigation into the occurrence rated an incident.

On Aug 28th 2020 the ATSB released their final report concluding the probable causes of the incident were:

- Oxidation and deterioration of the stage four No. 5 nozzle guide vane segment protective coating resulted in the development of intergranular oxidation in the parent material of the No. 6 aerofoil. This led to crack development, fracture and liberation of the aerofoil.

- The loss of the aerofoil led to downstream turbine rotor damage with significant loss of blade material and engine vibration. Due to the vibration, and in consideration of the potential for further engine damage, the flight crew decided to shut the engine down in flight and return to the departure airport.

The ATSB described the sequence of events:

The flight crew consisted of the aircraft captain who was the pilot flying (PF), the first officer as the pilot monitoring (PM) and a second officer.

QPI departed Sydney at 1219 Eastern Standard Time.2 As the engine thrust was being reduced from the take-off setting, the PM heard a ‘pop’ sound and the flight crew recalled receiving a flight deck advisory message, followed by light airframe vibration. A reduction of about 5 per cent in N13 revolutions per minute of the right (No. 2) engine was also noticed. The advisory message from the aircraft’s electronic centralised aircraft monitor (ECAM) indicated that the No. 2 engine’s vibration level had reached the maximum recordable level of 10 units. A later review of quick access recorder4 data showed that the ECAM message was generated at 1220:25 as the aircraft climbed through an altitude of 1,696 ft.

The PF reported that, despite the right engine vibration and reduction in N1, no yawing5 was present. The aircraft was configured with the undercarriage retracted, and autopilot engaged. As the aircraft gained altitude, the PF retracted the wing flaps and leading edge slats. The flight crew then responded to the advisory message and referred to the aircraft’s quick reference handbook, which directed them to the 'High Engine Vibration’ checklist.

By 1224:22, the flight crew had discontinued the climb and were maintaining an altitude of 7,000 ft in order to complete the ’High Engine Vibration’ checklist. The PF reported that in accordance with the checklist, the No. 2 engine’s thrust lever was reduced to idle, and the No. 1 (left) engine set to maximum continuous thrust.

With the No. 2 engine at idle, the vibration level reduced to 6.5 units. However the advisory message remained displayed as the threshold to remove the advisory was 5.7 units. The flight crew considered this level of vibration to be excessive, and discussed shutting down the No. 2 engine to prevent further damage. No additional alerts or advisory messages from the ECAM that related to engine parameters were presented to the flight crew for the remainder of the flight.

Given the ‘pop’ sound heard immediately prior to the onset of vibration, the ‘Engine Stall’ checklist was actioned. At 1231:47, about 12 minutes after take-off, the PF shut down the No. 2 engine.

With the No. 2 engine shut down, the airframe vibration ceased, and a holding pattern over Richmond, New South Wales was initiated. While holding, the flight crew communicated with air traffic control, appraised company representatives of the event, and briefed the cabin crew and passengers on the situation. The decision was made to return to Sydney and perform an overweight landing. The aircraft was not equipped with a fuel dump system and company procedures required that, when an aircraft was damaged, an overweight landing was to be performed to allow the aircraft to land as soon as practicable.

The flight crew referred to the ‘Overweight Landing’ checklist and discussed how they would conduct a single-engine approach and utilise the aircraft’s auto-land system as procedurally required. At 1307, after about half an hour of holding, a descent into Sydney was commenced. The PF reported that the descent was initially unstable, however between 1,000 and 500 ft above ground level, a stable approach was established. At 1317, QPI touched down at Sydney Airport on runway 16R6. It was taxied clear of the runway and inspected by airport fire services. On receiving clearance from the fire warden, the aircraft was taxied to the terminal and shutdown at 1319.

An initial inspection by engineering staff revealed visible damage to the No. 2 engine low-pressure turbine stages four and five. It also revealed that engine debris had caused impact damage to the lower surfaces of the aircraft’s right wing flaps and body fairings. The engine was subsequently removed and shipped to the engine manufacturer’s overhaul facility in Taiwan for detailed examination and repair.

The ATSB analysed:

Gas turbine engine, nozzle guide vanes (NGV) and turbine assemblies are subject to high mechanical loading and temperatures in a corrosive and erosive environment. Detailed technical examination identified that, following oxidation and deterioration of the protective coating on the stage four NGV, No. 5 segment, inter-granular oxidation developed in the base material of the aerofoils. This resulted in cracking of the highly stressed leading edge of the No. 6 aerofoil and its subsequent fracture and liberation.

The lack of damage ahead of the stage four NGV assembly indicated that the liberated aerofoil was the initial event that led to the engine damage. As the aerofoil continued aft in the gas stream, the stage four and stage five low-pressure turbines and the stage five NGV were damaged. The loss of turbine blade material caused a rotor imbalance that was felt as airframe vibration. The airframe vibration was still present following the power lever reduction to idle. Due to the level of residual vibration, the flight crew decided to shut the engine down in flight and return to the departure airport.