777 - 'You have ditched'

[Maverick]

No matter what the problem was, I hope the definintely get it nailed down and fixed. If it can happen once, it can happen several times.

[Ripsnort]

Here is the latest:  It appears both engines were running at the time of the crash:

Accident to a Boeing 777-236, G-YMMM, on 17 January 2008 - Initial Report Update


Accident to a Boeing 777-236, G-YMMM, on 17 January 2008 at 1243 hrs
Initial Report Update 23 January 2008

Since the issue of the Air Accidents Investigation Branch (AAIB) 1st Preliminary Report on Friday 18 January 2008 at 1700 hrs, work has continued on all fronts to identify why neither engine responded to throttle lever inputs during the final approach. The 150 tonne aircraft was moved from the threshold of Runway 27L to an airport apron on Sunday evening, allowing the airport to return to normal operations.

The AAIB, sensitive to the needs of the industry including Boeing, Rolls Royce, British Airways and other Boeing 777 operators and crews, is issuing this update to provide such further factual information as is now available.

As previously reported, whilst the aircraft was stabilised on an ILS approach with the autopilot engaged, the autothrust system commanded an increase in thrust from both engines. The engines both initially responded but after about 3 seconds the thrust of the right engine reduced. Some eight seconds later the thrust reduced on the left engine to a similar level. The engines did not shut down and both engines continued to produce thrust at an engine speed above flight idle, but less than the commanded thrust.

Recorded data indicates that an adequate fuel quantity was on board the aircraft and that the autothrottle and engine control commands were performing as expected prior to, and after, the reduction in thrust.

All possible scenarios that could explain the thrust reduction and continued lack of response of the engines to throttle lever inputs are being examined, in close cooperation with Boeing, Rolls Royce and British Airways. This work includes a detailed analysis and examination of the complete fuel flow path from the aircraft tanks to the engine fuel nozzles.

Further factual information will be released as and when available.

[Ripsnort]

Another update: Potential bad fuel/slush in fuel:

Jan 25, 2008
By Guy Norris/Aviation Daily
U.K. Air Accidents Investigation Branch inspectors are examining the fuel system of the British Airways Boeing 777-200ER which crash-landed at London Heathrow Airport last week after updating its preliminary findings to say that both engines did briefly produce some thrust during the approach.
The AAIB, which initially indicated that the 777's Rolls-Royce Trent 895 engines failed to respond to an auto-throttle command, now says both engines spooled up when commanded but that the thrust levels soon reduced. The number two (right) engine reduced after about three seconds, while the number one engine power reduced after about eight seconds. The findings appear to be consistent with post-crash photographs that indicate considerably more fan damage to the number one engine than the number two engine, which appears relatively intact. The fan damage indicates the number one engine was running at some power on impact.
Investigators say that "all possible scenarios that could explain the thrust reduction and continued lack of response to throttle-lever inputs are being examined," and adds that flight data recorder information indicates normal performance from both engine control commands and the auto-throttle.
According to the British Airways 777 technical manual the autothrottle is controlled by the thrust management function, which operates the autothrottle in response to flight crew mode control panel inputs or to automatic flight management computer (FMC) commands. Thrust management calculates reference thrust limits and thrust settings, or follows FMC thrust settings as well as commands the thrust levers themselves. The system is also designed to sense and transmit autothrottle failures and commands thrust equalization through the engine electronic controls. The thrust levers can also, of course, be set manually by the crew.
Sources close to the investigation also tell The DAILY that British Airways engineers have been collecting fuel samples from every flight emanating from China. The sample collection, plus comments from the AAIB indicating the aircraft had "adequate" fuel remaining on board at the time of the crash, is believed to point toward suspicions of a heavier-than-fuel contaminant being present. Theories propounded by crew include the possible presence of water in the tanks that, having become frozen during the intense cold-soak period of the flight, partially melted and formed a slush that could have partially blocked the fuel lines.
Sources also tell The DAILY that upper air temperatures over Russia and northern Europe were extremely cold on the day of the accident. Information from other crews coming from Asia on Jan. 17 encountered extremely low temperatures in the -70 to -75 degrees C. range, resulting in fuel temperatures dipping into the -40s. European upper air temperatures also indicate the last 6.5 hours of the inbound China flight would have been flown at an outside air temperature of -60 deg. C. or lower. Although this would have resulted in fuel temperatures on approach in the -35 degrees C range, this would not normally constitute a problem unless, potentially, contaminants were present.

[chase4]

It's a hell of a coincedence that both engines should fail at the same time (at any time for that matter).  They're just lucky that they were on finals or a much bigger incident could have happened, i.e the plane landing smack bang in the middle of the surrounding housing estates.  IMO the pilot has intended to land on the grass in the hope that it could "soften" the impact.


to the "hero" pilot (ironically name John Coward)

[SFRT - Frenchy]

Not trying to steal anyone's thunder, but in my opinion the pilot had little room to work with. He surely did not pick his landing spot. He however did an outstanding job at managing his airspeed during his partial engine failure to "ride her down".

[Ripsnort]

Originally posted by chase4
It's a hell of a coincedence that both engines should fail at the same time (at any time for that matter). They're just lucky that they were on finals or a much bigger incident could have happened, i.e the plane landing smack bang in the middle of the surrounding housing estates.  IMO the pilot has intended to land on the grass in the hope that it could "soften" the impact.


to the "hero" pilot (ironically name John Coward) [/B]

If you read that last portion of the article I pasted, it appears may have not been coincidence.

Sources close to the investigation also tell The DAILY that British Airways engineers have been collecting fuel samples from every flight emanating from China. The sample collection, plus comments from the AAIB indicating the aircraft had "adequate" fuel remaining on board at the time of the crash, is believed to point toward suspicions of a heavier-than-fuel contaminant being present. Theories propounded by crew include the possible presence of water in the tanks that, having become frozen during the intense cold-soak period of the flight, partially melted and formed a slush that could have partially blocked the fuel lines.
Sources also tell The DAILY that upper air temperatures over Russia and northern Europe were extremely cold on the day of the accident. Information from other crews coming from Asia on Jan. 17 encountered extremely low temperatures in the -70 to -75 degrees C. range, resulting in fuel temperatures dipping into the -40s. European upper air temperatures also indicate the last 6.5 hours of the inbound China flight would have been flown at an outside air temperature of -60 deg. C. or lower. Although this would have resulted in fuel temperatures on approach in the -35 degrees C range, this would not normally constitute a problem unless, potentially, contaminants were present.

[Maverick]

Rip, no provision for fuel tank and line heating other than returned fuel?

[Ripsnort]

Originally posted by Maverick
Rip, no provision for fuel tank and line heating other than returned fuel?

Fuel tanks are heated to accomodate the freezing temperature of jet fuel but water freezes at a different temp than jet fuel. Looks like they encountered some extreme temperatures. I'm not sure if even a heated system could keep up with those sort of extremes and situation (water, fuel and contaminates) unless its on a thermostat....

I think what the article is saying that extremely cold jet fuel, water,  mixed with contaminates could create a "slush" that would seize fuel lines.

[Airscrew]

so maybe what I said back on the 18th

Originally posted by Airscrew
ok, was trying to be a bit funny,  let me say it another way,..

fuel starvation? blocked fuel lines?

[Maverick]

Originally posted by Ripsnort
Fuel tanks are heated to accomodate the freezing temperature of jet fuel but water freezes at a different temp than jet fuel. Looks like they encountered some extreme temperatures. I'm not sure if even a heated system could keep up with those sort of extremes and situation (water, fuel and contaminates) unless its on a thermostat....

I think what the article is saying that extremely cold jet fuel, water,  mixed with contaminates could create a "slush" that would seize fuel lines.

Rip,

JP like diesel will gel before it freezes. I understand about the slush but I also figured that the fuel would be maintained above the freezing point of water just for that reason. That's why I asked about provisions for heating other than just returned fuel. I know the engines pump far more fuel than they use so returning fuel, if routed around the engine, would certainly be warm returning to the tanks.

[Vulcan]

Chinese fuel huh? Did they check it for lead?