|Title:||Contained engine failure and rejected takeoff, Boeing 747-236B, G-BDXO, 14 October 1996|
|Micro summary:||This Boeing 747-236B experienced a contained engine failure, which led to an aborted flight.|
|Event Time:||1996-10-14 at 2119 UTC|
|Publishing Agency:||Aircraft Accident Investigation Board (AAIB)|
|Publishing Country:||United Kingdom|
|Site of event:||Takeoff, London Gatwick Airport|
|Departure:||Gatwick Airport, London, England|
|Destination:||Harare International Airport, Harare, Zimbabwe|
|Airplane Type(s):||Boeing 747-236B|
|Type of flight:||Revenue|
|Executive Summary:||The aircraft had begun its take-off roll on a flight to Harare, Zimbabwe. The Flight Data Recorder subsequently showed that take-off power was set by 80 kt, but Turbine Gas Temperature (TGT) on the No 1 engine increased slightly, accompanied by small fluctuations in Engine Pressure Ratio (EPR). As the aircraft reached V1 at 144 kt there was a bang followed by audible surging,the TGT started to rise sharply and there was a step increase in the vibration indication. Flame and sparks were seen coming from the jet pipe by some passengers and ground observers. Power was reduced as the TGT passed 784°C and momentarily peaked at 804°. Take off was continued and the No 1 engine was shut-down at about 300 ft AGL. The aircraft jettisoned fuel and returned to Gatwick without further incident. |
Borescope inspection revealed considerable High Pressure Compressor (HPC) damage and a subsequent strip examination showed severe secondary damage to stages 4, 5 and 6 of the HPC caused by release of a stage 3 stator vane airfoil which had apparently cracked away from its inner and outer shrouds. In this particular model of the RB211 engine, the HPC3 stators are of fabricated design,with the airfoil being brazed to the inner and outer shrouds and are assembled as single vanes to form the complete stage. The remaining stages are of forged construction, separate vanes being brazed together in groups of six.
The operator reports that they have not experienced problems before on the HPC3 stator vanes on the RB211-D4 engine but had encountered problems with the HPC4 vanes on their RB211-535C engines which were also of fabricated construction and were addressed by a change to a forged standard. With this experience in mind, they report that they are giving serious consideration to embodying Rolls-Royce modification 72-7342 on refurbishment of the HPC of their fleet of engines. This modification changes the construction of the HPC3 stator vanes on the 524D4 engines from fabricated to forged. The engine in question had flown 61,288 hours/9,980 cycles since new and 3,821 hours/570 cycles since last workshop visit.
|Learning Keywords:||Operations - Bang, pop, crack, sizzle!|
|Systems - Engine - Contained Engine Failure|
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