Investigation Update

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Investigation Update=0AAllegedly leaked information and photos on the Pilot=
sofAmerica.com forum. Very interesting stuff here if it's confirmed.=0A=0A=
=0AAt about 700 ft AGL, the auto throttle commanded engine acceleration. On=
e engine started to rollback during and the other engine started to acceler=
ate then 8-10 seconds later began to roll back. Once the flight crew notice=
d, they pushed the throttles up and the engines' EECs responded but the eng=
ines did not. It appears that no fuel was getting to the engines. =0AThe in=
vestigation continues to look broadly for a cause of the dual engine rollba=
cks. Fuel exhaustion is the only item that has been positively ruled out. A=
spects that the FAA believes the investigation is concentrating on are:=0A=
=95 Ice in the fuel somehow limiting the fuel flow to the engines. A mainte=
nance message indicating excessive water in the center tank was set during =
taxi on the two previous flight legs, although it cleared itself both times=
. The airplane was being operated in a high humidity, cold environment, con=
ducive to ice formation.=0A=95 Small-sized contamination building up in the=
 engine fuel systems somehow limited the fuel flow to engine. All the fuel =
samples have tested for contamination of larger particles (sizes outside th=
e fuel specification). Testing has been started looking for small particles=
 (greater than 5 microns).=0A=95 Engine hardware failures sending inaccurat=
e data to the engine electronic control (EEC) causing the EEC to demand ins=
ufficient fuel. A preliminary review of the EEC data from the right engine =
shows erratic combustor inlet pressure (P30). A leaking P30 sense line coul=
d cause this, or the EEC receiving a higher than actual fuel flow parameter=
.=0A=95 Software coding problem in the EEC causing the EEC to demand insuff=
icient fuel. British Airways installed a new engine EEC software revision i=
n December 2007. The software was approved in May 2006. There were several =
changes to the software as part of the revision. Two items seem remotely re=
lated to the accident: improvements to low power stall recovery logic and f=
an keep out zones for ground maintenance. The first two items would be rela=
ted to a part 25 compliance issue, while the last two items would be relate=
d to a part 33 compliance issue.=0AMUCH MORE BELOW THE FOLD=0AAs stated yes=
terday in this briefing paper, the electrical system anomalies noted earlie=
r have been resolved, as describe below, and the conclusion now is that the=
 electrical buses were powered until impact and performing as expected.=0A=
=95 The auxiliary power unit (APU) began its auto start sequence, even thou=
gh the buses were still powered. In the days following the event, the fligh=
t crew has added additional details to their report. The crew now believes =
they turned the APU on prior to impact. There was sufficient time before th=
e impact for the APU inlet door to open, but not for the APU fuel pump to t=
urn on or the APU engine to start spooling up.=0A=95 The quick access recor=
der (QAR) saved data and shut down approximately 45 seconds prior to impact=
. The QAR saves data in batches. It is believed the QAR was working properl=
y and was in the process of saving data when impact occurred, accounting fo=
r the =93lost=94 45 seconds of data.=0A=95 The fuel crossfeed valves were c=
losed in flight according to the flight crew, but the switches were found i=
n the open position and only one valve was open. In the days following the =
event, the flight crew has added additional details to their report. The cr=
ew now believes they opened the valves just prior to impact and the airplan=
e lost power before both valves moved to the open position.=0A=95 The ram a=
ir turbine (RAT) was found deployed, even though the buses were still power=
ed. It did not deploy until after the airplane came to a stop, as determine=
d by the pristine condition of the turbine blades. The RAT either deployed =
due to electrical power loss during impact with a failed air/ground signal =
or the impact unlatched the RAT door.=0AFuel system: Leads regarding water =
in the fuel and fuel contamination are continuing to be investigated. Fuel =
testing looking for small-sized contaminants (5 microns) is beginning. The =
tanks are still being drained and the team hopes to start evaluating the fu=
el system hardware tomorrow.=0AEngines: Component testing and teardown of t=
he engine-driven fuel pumps and the fuel metering units is planned for late=
r this week. The data from the electronic engine controls is still being an=
alyzed. Rolls-Royce is planning an engine test, unscheduled as yet, to try =
and duplicate the rollbacks.=0ACrashworthiness: Cabin crew and passenger qu=
estionnaires indicate that the evacuation bell was faint, but the evacuatio=
n light was seen and the captain=92s message to evacuate over the passenger=
 address system was heard. Preliminary data indicates that the descent rate=
 at impact was roughly 30 ft/sec. Dynamic seat requirements that became eff=
ective at the introduction of the Model 777 series airplanes require seats =
protect occupants for hard landing impact up to 35 ft/sec. The passenger wi=
th the broken leg was sitting next to the point where the right main landin=
g gear punctured the fuselage and pushed into the cabin (pictured below).=
=0ACrashworthiness: There was only one serious injury, a compound fracture =
to the leg. The airplane landed on the main gear, bounced, came back down o=
n the gear, then the gear failed, and the engines supported weight of the a=
irplane. The descent rate at landing was 1500-1800 feet per minute. One of =
the main landing gear swung around and pushed slightly into the cabin. The =
other punctured the center fuel tank (empty) leaving a 1-by-2-foot hole. Th=
e report of a fuel leak is unconfirmed. All the slides deployed and the doo=
rs worked. Some passengers had to shuffle down the slides due to the slight=
 angle. The flight deck door opened on its own during the landing. Some oxy=
gen masks dropped. =0A*Surprised by what you have read?Do you think this re=
port has gone any closer to establishing the true reason for the crash? Hav=
e youir say on AirSpace=0ATags:=0A777 =0ABoeing =0ABritish Airways =0APoste=
d by Jon Ostrower on January

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