A Boeing 777-321ER had departed Singapore Changi International Airport short after 02.00lt on a ~10.259 kilometers (~6412 miles) flight to Milan Malpensa Airport (Italy). After levelling off at 30.000 feet, to avoid weather, and approximately 30 minutes after take-off the crew noticed the oil quantity for the right engine had dropped to 1 unit on the EICAS (Engine Indicating and Crew Alerting System) while the oil pressure was fluctuating and the oil temperature was 10ºC higher than the left engine.
The engine and wing are on fire (source; i.ytimg.com © Unknown)
The crew was unable to find a procedure for the low oil quantity. After contacting the company's maintenance department via SATCOM (Satelite Communication) the crew initially was advised to continue to their destination. Shortly after the call with the company's maintenance department a burning smell was observed momentarily in the fligthdeck but cleared quickly with no abnormal indications. Approximately 2 hours into the flight the crew contacted the maintenance department again, this time because of vibrations felt when th thrust setting of the right engine was changed. During the call, the Purser informed the pilots that there was a burning smell in the cabin. The decision was made to return to Singapore, following the procedure for single-engine operation the aircraft descended to 17.000 feet and the right engine thrust was reduced to idle. During the flight back to Singapore, at 05.21 a FUEL DISAGREE message was presented on the EICAS. The calculated (Flight Management System) fuel quantity was 83 tons, while the indicated quantity was 79 tons, 4 tons of fuel were missing. The crew made some calculations and concluded that the 79 tons indication was correct, and there was no fuel leak.
Fire damage to the flaps on the right-wing (Source and © mot.gov.sg) ATC queried several times if any assistance was required, to which the crew replied that the only abnormality was an engine at idle and a flight at a lower altitude, no assistance was required. During the flight back to Singapore 41.500 kg (91.500 lbs) of fuel was jettisoned to reduce the aircraft's landing weight. At 06.49 local time, the aircraft landed at Singapore-Changi, 20 seconds after reverse thrust was selected on both engines two loud bangs were heard in the aircraft (and two bright flashes were seen from the cabin).
ATC also saw the flashes, as well as the ARFF (Airport Rescue and Firefighting Service) who were monitoring the aircraft's arrival. ATC instructed the crew to stop the aircraft because of the fire and cleared the ARFF to enter the runway and attend to the aircraft, ARFF was at the aircraft after 57 seconds and started applying foam to the fire and quickly brought the fire under control.
At 07.10lt the passengers started leaving the aircraft via mobile steps brought out to the aircraft. 21 minutes later all passengers had left the aircraft.
There was extensive damage to the right-wing and engine area caused by the fire.
Fire damage to the righthand engine (left), and the failed tube in the Main Fuel Oil Heat Exchanger. (Source and © mot.gov.sg)
The incident was investigated by the Transport Safety Investigation Bureau, they published their extensive report (available by clicking here) after 8 months of investigation, A long list of conclusions and safety actions are listed in the report, here is a summary of the conclusions from the report;
A fuel leak in the Main Fuel Oil Heat Exchanger (MFOHE) caused fuel to accumulate in various areas of the engine.
When reverse was selected conditions occurred that caused ignition of the accumulated fuel.
The crew did not execute the FUEL DISAGREE checklist
Video of the fire after landing (Source: youtube.com ©The Straits Times)