Inquiry details BA 777 engine incident similar to Emirates event

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UK investigators have detailed an incident in which a British Airways Boeing 777-200ER continued a flight despite suffering engine damage on take-off, an event apparently similar to one this year involving an Emirates 777-200ER.

As the BA aircraft departed Singapore for London, on 14 June last year, it experienced exhaust gas temperature fluctuations in its right-hand Rolls-Royce Trent 800 powerplant at 500ft. Caution messages over the engine thrust and engine speed appeared briefly but the symptoms disappeared and the flight continued.

While climbing through 10,000ft the captain conducted a troubleshooting check by engaging full thrust. Both engines appeared to be running normally but the crew discussed a discrepancy in readings between the two.

Only after 5h flying did the situation start to deteriorate, when calculations indicated that reaching London with minimum required fuel of 5.4t was "becoming unlikely" and the trend was "worsening", said the Air Accidents Investigation Branch.

The 777 was over Afghanistan at this point, and few suitable alternate airports would be available for several hours, even if the aircraft turned back. Since the aircraft was burning 8t per hour and there was still 52t of fuel on board, the crew opted to continue towards Europe.

Around 8h 45min into the flight, the high fuel flow and required thrust setting reduced after the crew felt and heard a "thud", which the captain initially thought to be a compressor stall. The fuel state stopped deteriorating, but with inadequate fuel for London the crew planned a diversion to Amsterdam.

The aircraft landed without incident. But inspection showed an inner wall duct on the thrust reverser had separated and a large part of the turbine exhaust nozzle was missing. The 777 had sustained damage to its inboard flap fairing and flaperon, and there was gouging on the wing skin and horizontal stabiliser. Debris was found by the runway at Singapore.

Earlier this year an Emirates 777 continued a 5h flight despite the crew's hearing a loud bang and receiving a number of cautionary messages while departing Moscow. That aircraft had also suffered duct and thrust-reverser damage.

In its report into the BA incident, the AAIB said there were several areas within the engine duct that showed evidence of "thermal exposure and disbond". It added that the incident followed around 10 other events on 777s with the same airframe-engine combination, and that two more had occurred since.