AAIB Report into 3-Engined 747 over London
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Re: AAIB Report into 3-Engined 747 over London
Having watched the Evergreen B747-200F make its steep turns to lose altitude and make a safe approach and landing, I thought it was a very well flown maneouvre and ATC deserved praise for complying with the Captains' intention to fly a visual approach to an airport with two long runways.
The point about having charts is irrelevant for an emergency landing in clear conditions. ATC will provide relevant information required by the crew.
Regarding icing, fuel icing may have been a factor for the investigation, but airframe icing almost certainly was not, given the weather conditions between Ramstein and Heathrow.
As for impounding the aircraft - for what reasons?
The incident ended safely for all concerned, including all those millions who happened to be under the aircrafts' flight path - why speculate on what horrors may have occurred? Both crew and air traffic controllers acted as trained and in accordance with current legislation.
The point about having charts is irrelevant for an emergency landing in clear conditions. ATC will provide relevant information required by the crew.
Regarding icing, fuel icing may have been a factor for the investigation, but airframe icing almost certainly was not, given the weather conditions between Ramstein and Heathrow.
As for impounding the aircraft - for what reasons?
The incident ended safely for all concerned, including all those millions who happened to be under the aircrafts' flight path - why speculate on what horrors may have occurred? Both crew and air traffic controllers acted as trained and in accordance with current legislation.
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Keeping in mind, I know very little about 747's, it sounds from the report that the crew may have misinterpreted the engine guages or been given faulty information by the engine indication display system. After the engine failure, they descended to FL210 at which point "the air speed began to decrease significantly which the co-pilot drew to the attention of the commander."
There was according to figure three, a 20 knot decrease over two and a half minutes at which point there was a further descent. In the simulator when flying a similar profile with slightly different engines, there was a 20 knot decrease over three minutes.
Further, "The commander was seen by the co-pilot to advance the Nos 2 and 4 thrust levers one at a time but the EPRs remained the same with the EGTs increasing to approximately 890ºC with no detectable corresponding forward acceleration. Further operation of the thrust levers was considered but the commander did not wish to compound his problems by possibly flaming out the remaining engines."
The report goes on to quote this from the operator's 747 operations manual "Slow engine acceleration and/or slow EPR response at high altitude could be misinterpreted as lack of engine response to thrust lever movement. Due to the engine inlet air spillage at low thrust settings near idle and the possibility of false EPR indications, other engine parameters should be monitored. If engine thrust appears to be unresponsive in terms of EPR, advance the thrust lever and monitor N1, EGT and Fuel Flow increase; normally EPR should respond in approximately 15 to 20 seconds. Engine acceleration time up to one minute may be experienced. If N1, EGT and Fuel Flow do not respond normally, or if the engine has flamed out, refer to Abnormal Procedures”.
I don't know if FL 210 is considered the high altitude mentioned in this caution.
Power was available on approach and taxi in.
Also important to remember is that when checked on the ground by an engineer, a wet cycle on #1 produced no N1 or FF. #2 engine showed no N1 or FF when started. "the engineer found a BITE (Built-In Test Equipment) fault on the EIDS which led him to change the right-hand display unit and clean the ‘Cannon’ plugs for the EIDS system." The report doesn't mention if there was an attempt to start #3 and #4 before the EIDS was replaced. This could be the source of some or all of the problem after #1 was shut down.
There was according to figure three, a 20 knot decrease over two and a half minutes at which point there was a further descent. In the simulator when flying a similar profile with slightly different engines, there was a 20 knot decrease over three minutes.
Further, "The commander was seen by the co-pilot to advance the Nos 2 and 4 thrust levers one at a time but the EPRs remained the same with the EGTs increasing to approximately 890ºC with no detectable corresponding forward acceleration. Further operation of the thrust levers was considered but the commander did not wish to compound his problems by possibly flaming out the remaining engines."
The report goes on to quote this from the operator's 747 operations manual "Slow engine acceleration and/or slow EPR response at high altitude could be misinterpreted as lack of engine response to thrust lever movement. Due to the engine inlet air spillage at low thrust settings near idle and the possibility of false EPR indications, other engine parameters should be monitored. If engine thrust appears to be unresponsive in terms of EPR, advance the thrust lever and monitor N1, EGT and Fuel Flow increase; normally EPR should respond in approximately 15 to 20 seconds. Engine acceleration time up to one minute may be experienced. If N1, EGT and Fuel Flow do not respond normally, or if the engine has flamed out, refer to Abnormal Procedures”.
I don't know if FL 210 is considered the high altitude mentioned in this caution.
Power was available on approach and taxi in.
Also important to remember is that when checked on the ground by an engineer, a wet cycle on #1 produced no N1 or FF. #2 engine showed no N1 or FF when started. "the engineer found a BITE (Built-In Test Equipment) fault on the EIDS which led him to change the right-hand display unit and clean the ‘Cannon’ plugs for the EIDS system." The report doesn't mention if there was an attempt to start #3 and #4 before the EIDS was replaced. This could be the source of some or all of the problem after #1 was shut down.
