A Boeing 747-436, powered by 4 Rolls-Royce RB211-524G turbofan engines, was scheduled to perform a scheduled passenger flight from Los Angeles International Airport (Ca. USA0 to London Heathrow International Airport (United Kingdom). Onboard, 18 crew and 352 passengers. During the flight preparation, it was decided to take
4.000 kg of additional fuel, due to forecasted weather and possible delays in the London TMA, the ramp fuel total was 119.000 kg. And at 05.24 the aircraft took off from Runway24L with the first officer as pilot flying. The flight crew was a "heavy crew, the Captain and First Officer and a second First Officer as cruise relief pilot.
Rolls-Royce RB211-524G turbofan engine (Source: Rolls Royce)
The take-off was normal, the gear was selected up, at 100 ft AGL a continuous "BUMP, BUMP, BUMP" was heard from the lefthand side of the aircraft, and a little yaw tendency was observed which was easily controlled by the first officer. A scan of the engine instruments revealed a reduction in #2 engine EPR (Engine Pressure Ratio) while the EGT (Exhaust Gas Temperature of the engine was rising. It continue to rise above the normal limits and an exceedance was indicated to the crew in red. At the same time, ATC called the aircraft stating they saw flames on the left side of the aircraft, In accordance with the operators to procedures the failure was identified and confirmed to be the #2 engine, after which the captain (pilot monitoring) performed the required memory (recall actions) in accordance with the QRH procedure for "ENGINE LIMIT/SURGE/STALL" With the throttle in idle, the abnormal indications ceased and the engine appeared to be operating normally. At 1500 feet AGL a 'PAN PAN' call was made and ATC cleared the aircraft to continue its climb to 5000 feet. After the flaps were retracted the Captain (in accordance with procedures) carefully advanced the throttle for the #2 engine, which resulted in the engine surging again, after increasing their speed they tried again, again the engine #2 surged, The crew decided to shut the engine down and carried out the required steps in accordance with the QRH. After which the second First Officer went into the cabin for a visual check of the engine and wing and to brief the purser on what had happened. In the Flight Management Computer, the "Eng Out" option had been selected, aircraft manuals and company procedures were checked to determine the course of action. Additionally, the captain had contacted their base in London to discuss the situation. They had indicated that they would prefer the flight to continue but the Captain had to take the decision.
Great Circle route from Los Angeles to London Heathrow, 4741 nm / 8780 km (Source; http://gc.kls2.com/)
The decision was made to continue the flight based on the following factors;
Arrival fuel was predicted to be 7.000 kg (4.500 was the minimum required reserve).
An additional engine failure was considered, but it was deemed safe to continue.
Initial routing over the USA provided plenty of suitable diversion airfields.
The current situation did not require an overweight landing or immediate fuel dumping.
#2 Engine parameters were normal for a windmilling engine
company policy was to continue to the destination as long it was safe to do so.
Boeing's QRH did not require the crew to (consider) landing for their situation.
The "PAN PAN" call was cancelled and ATC was informed of their intentions. The aircraft climbed to FL 270 and cruised across the USA at a speed of Mach 0.75. The fuel forecast improved and now showed a 10.000 kg arrival fuel. The captain, in consultation with both First Officers, decided to continue across the North Atlantic on three engines. The requested flight level for the Atlantic crossing was not available (FL320) and the crossing would have to be made at FL290. This gave them a landing fuel of ~7.500 kg. (the crew had 'set' a landing fuel limit at 6.500 kg's as an extra safety barrier) However, it became apparent during the later stage of the Atlantic Crossing the headwinds were stronger than forecasted this resulted in a higher fuel burn, with the FMC predicting an arrival fuel of 6.500 kg.
The decision was made to divert to Manchester (United Kingdom), during the diversion a "FUEL QTY LOW" was indicated with the N0 4 tank indicating only 900 kg. In accordance with company procedures, a 'MAYDAY' call was made as the captain was concerned they would be landing with less than the required 4.500 kg. The captain became pilot flying and an uneventful manual landing was made at Manchester. The cause of the engine failure was investigated by the Air Accident Investigation Branch and determined to be caused by excessive wear, causing the engine High-Pressure Compressor to stall."The full AAIB report is available by clicking here.
Boeing training video on Compressor Stall, (Source Boeing)
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