A Virgin Australia Fokker 100 crew decided to continue flying 355 kilometres to their destination when one of their engines flamed out – rather than turn around and land just 41 kilometres away at Geraldton.
The ATSB suggested the decision to proceed to Perth resulted in “longer exposure to one engine inoperative flight risks” but maintained it was still a “permitted option” that was carefully considered.
The aircraft was carrying two flight crew, two cabin crew and 24 passengers on board when the incident took place on 9 July 2019.
Virgin Australia said in response that “expanded training” would “reinforce the importance of inflight decision making and the effective management of these situations” to ensure flight crew are well placed to respond to future occurrences.
The Virgin Australia Regional Airlines-operated Fokker 100, VH-FWI, was climbing through 13,000 feet when its left Rolls-Royce Tay engine flamed out, which an ATSB investigation subsequently determined was due to the failure of the engine’s fuel flow regulator due to component wear.
After the flame-out, the flight crew elected to maintain their airspeed of 250 knots and to continue to Perth. In addition, due to a desire not to ‘strain’ the right engine, the pilot flying elected not to increase thrust from climb to maximum continuous, and/or reduce the aircraft’s speed towards the recommended single-engine climb speed of 155–170 knots.
Consequently, the crew adopted a cruise level about 6,500 feet below the maximum engine-out altitude.
“Following the engine failure, the crew’s decision to continue to Perth, where the aircraft landed without further incident, resulted in a longer exposure to one engine inoperative flight risks, compared to a diversion to the nearest suitable airport, which in this case was Geraldton,” said ATSB acting director of transport safety, Kerri Hughes.
At the time of the engine failure, the aircraft was about 41 kilometres south‑east of Geraldton and 287 kilometres from Perth if flying directly. The aircraft actually flew a more indirect route to Perth, 355 kilometres away.
The investigation report notes that the crew probably assessed that the likelihood of a second engine failure was remote, but may not have fully contemplated the operational risks associated with continued single-engine flight at the lower altitude of 14,000 feet.
Consequently, opportunities were missed to further mitigate operational risk via repositioning the aircraft into controlled airspace, more direct tracking to Perth and the optimisation of their glide range.
“By electing not to increase thrust on the right engine or adopt the aircraft’s recommended single-engine climb speed reduced the available climb performance of the aircraft resulting in a lower cruise altitude than the maximum available,” said Hughes.
“This, coupled with the decision to continue to Perth on the original indirect track, increased the duration of flight and the time that the aircraft was outside the glide range of emergency airports and controlled airspace, in the unlikely event that the second engine failed.”
In the full report, the ATSB said the crew choose to continue to Perth because of poorer weather and more traffic in Geraldton, plus a longer runway and better emergency service support in the WA capital.
The investigation found the fuel flow regulator seized due to internal gearing wear, despite being maintained within the recommended service life limits of the Rolls-Royce Tay 650-15 engine management program.
The ATSB also identified that the failure of the fuel flow regulator resulted in engine one thrust variation for about 45 seconds prior to the engine flame-out.
That went undetected by the crew due to the effects of automation, focused attention on other cockpit tasks, and the absence of any alert prior to the engine failure.
Following this incident and a review of the global failure rate specific to the fuel flow regulator unit utilised by the Virgin Australia Fokker 100 fleet, Rolls-Royce amended the applicable component management plan revising the recommended full-life maximum overhaul interval for the fuel flow regulator down from 16,000 to 10,000 hours.
“This incident highlights that the initial indications of component failures and malfunctions may be subtle. Automation can obscure significant changes in aircraft system status, including engine health,” said Hughes. “The incident also illustrates the numerous factors to be considered when managing the initial and subsequent aspects of power loss in a complex aircraft.”
Virgin Australia said in a statement, “The safety and wellbeing of our guests and crew is our top priority, and we always exercise caution to ensure we appropriately manage the many factors involved in these situations.
“We welcome the review by Rolls-Royce and its management plan to recommend changes to the time between
overhauls of the fuel flow regulator (FFR) component, down from 16,000 to 10,000 hours.
“This, alongside expanded training that reinforces the importance of inflight decision making and the effective
management of these situations ensures our flight crew are well placed to respond to future occurrences.”