BA Boeing 777 Crash Lands at LHR

[mgh 89]

The AAIB has issued a further interim report.http://www.aaib.dft.gov.uk/cms_resources/S...08%20G-YMMM.pdfIt's found that:- the recodared data showed no signs of anomalies in the major aircraft systems - there were signs of abnormal cavitation inboth left an right high pressure fuel pumps- debris was found in the the right main tank, left main tank water scavenge inlet, right centre tank override pump, left centre tank water scavenge jet pump. These included a plastic sealer scraper, black plastic tape, brown paper, yello plastic, fabric or paper, and a small circular disk. - initial fuel samples showed it conformed to Jet A-1, snd there were no signs of contamination or unusual levels of water. AAIB draws no conclusions and investigations are continuing.It recommended that Boeing notify all opertors of the need to operte the fuel control switch to cut-off prior to operation of the fire handle to avoid the possibility of the engine fuel spar shut-off valves being left in the open position which happened in this case. Boeing accepted this recommendation.

[scoob 18]

>- debris was found in the the right main tank, >left main tank water scavenge inlet, right >centre tank override pump, left centre tank >water scavenge jet pump. These included a >plastic sealer scraper, black plastic tape, >brown paper, yello plastic, fabric or paper, >and a small circular disk.list reads like fuel tanks not cleaned correctly during construction and/or after systems check. as the paperwork trial will show who was where when on any part of the aircraft some person(s) will be getting some serious Q&A in everett, seattle and all BA's aircraft maintenance providers.--

[scott967 62]

It is interesting that everything seemed to operate to send the proper volume of fuel into the engines, yet it didn't. Very strange. scott s..

[Cessnaflyer 56]

>It is interesting that everything seemed to operate to send>the proper volume of fuel into the engines, yet it didn't. >Very strange. >>scott s.>.>Not really that strange. The report says that cavatation happened at the high pressure pumps. These things are so high powered that this can happen with a small interruption of the low powered fuel jets that supply fuel to the high pressure jets.

[scott967 62]

OK, but we don't know when the cavitation occurred. Do you think that the cavitation happened very close to the event? How long would the cavitation lasted? And the cause of the interruption of the low pressure fuel pumps (both engines), if this was the cause of cavitation, hasn't been explained.

[mgh 89]

AAIB aere still only reporting the facts as it finds them. It will draw its conclusions later when it's sure it has fully analysed all the facts.

[michal 44]

>list reads like fuel tanks not cleaned correctly during>construction and/or after systems check. What makes you think it happened during construction? This airplane could have gone already through a few B,C checks or other ground maintenance procedures during which debris could have been deposited.Michael J.http://img142.imageshack.us/img142/9320/apollo17vf7.jpg

[Roger Mazengarb 0]

>It recommended that Boeing notify all opertors of the need to>operte the fuel control switch to cut-off prior to operation>of the fire handle to avoid the possibility of the engine fuel>spar shut-off valves being left in the open position which>happened in this case. Boeing accepted this recommendation. I'm having difficulty comprehending this. On every Boeing I've worked on (admittedly not B777) the fire handle, when pulled, had priority over the cockpit switch for the fuel shut-off valve and would close the fuel valve irrespective of the cockpit switch position. Is this not the case for the B777? Why wouldn't (didn't) the fire handle close the fuel valves? Anyone any wiser?Roger

[scoob 18]

>>list reads like fuel tanks not cleaned correctly during>>construction and/or after systems check. >>What makes you think it happened during construction? This>airplane could have gone already through a few B,C checks or>other ground maintenance procedures during which debris could>have been deposited.Michael J.:yes you are right all the 'stuff' could have come after construction which is why i said, ".../or after systems check." lots of folks look at an airplane. all folks report they looked/touched/did something.--

[mgh 89]

Read the AAIB report which explains why in detail.http://www.aaib.dft.gov.uk/publications/sp..._er__g_ymmm.cfm

[bob.bernstein 0]

thanks mgh, interesting read.

[Roger Mazengarb 0]

Thanks for the link. Roger

[mgh 89]

The latest AAIB report says "the investigation has established that it is possible for sufficient ice to build up within the fuel system, such that its sudden release would cause a restriction at the Fuel Oil Heat Exchanger (FOHE) sufficient to cause an engine roll back". The roll back would be triggered by the consequent increase in engine oil temperature.http://www.aaib.gov.uk/cms_resources/Inter...20%20G-YMMM.pdf

[mgh 89]

The UK AAIB has published its final report. The synopsis reads:The investigation identified the following probable causal factors that led to the fuel flow restrictions: 1) Accreted ice from within the fuel system released, causing a restriction to the engine fuel flow at the face of the FOHE, on both of the engines. 2) Ice had formed within the fuel system, from water that occurred naturally in the fuel, whilst the aircraft operated with low fuel flows over a long period and the localised fuel temperatures were in an area described as the 'sticky range'. 3) The FOHE, although compliant with the applicable certification requirements, was shown to be susceptible to restriction when presented with soft ice in a high concentration, with a fuel temperature that is below -10

[Ray Proudfoot 8,954]

NATS have released the recording of the incident and it's available on the BBC here. http://news.bbc.co.uk/1/hi/uk/8505174.stmIt gives me great satisfaction to hear how calm all involved are in such chaotic circumstances. Tower are so matter-of-fact you'd think it was a training exercise.