BA 777 Emergency Landing Short of Runway at LHR

Apols, don’t know the true source, but it will be a reliable one (It was sent to me by a Pilot)

The US’s National Transportation Safety Board is probing an
“uncommanded rollback” on a Rolls-Royce Trent 895 engine which
affected a Delta Air Lines Boeing 777-200ER on 26 November, Flight
International reports.

NTSB explains that Delta Flight 18, from Shanghai to Atlanta,
experienced loss of thrust on the right-hand engine at 39,000ft. Its
initial report elaborates: “Initial data indicates that following the
rollback, the crew descended to FL310 (approximately 31,000ft) and
executed applicable flight manual procedures. The engine recovered and
responded normally thereafter. The flight continued to Atlanta where
it landed without further incident.”

Senior investigator Bill English – due to meet Boeing regarding the
incident – is apparently “looking into” the possibility there might be
similarities to the Heathrow 777 incident which saw BA038 (G-YMMM)
suffer reduced thrust in both Rolls-Royce RB211 Trent 895-17 engines
while coming into land and fall short of the runway.

An Air Accidents Investigation Branch (AAIB) report into BA038
concluded “that the fuel flow to both engines was restricted; most
probably due to ice within the fuel feed system”. It added: “The ice
is likely to have formed from water that occurred naturally in the
fuel whilst the aircraft operated for a long period, with low fuel
flows, in an unusually cold environment.”

Flight International notes that in light of the AAIB findings, the
Federal Aviation Administration back in September “issued an
airworthiness directive calling on operators of 777-200 and -300
aircraft equipped with Trent engines to revise flight manuals to
include in-flight procedures for pilots to follow during certain
cold-weather conditions and for operations on the ground”.

English and fellow investigators are now examining the Delta
aircraft’s flight data recorder “and other applicable data and
components”. ®

FYI,

http://www.aaib.dft.gov.uk/cms_resources/G-YMMM%20Interim%20Report.pdf

Apologies if this has been posted before but the crew have all been awarded BA’s highest acolade for their professionalism.

http://bapress.custhelp.com/cgi-bin/bapress.cfg/php/enduser/std_adp.php?p_sid=&p_lva=&p_faqid=7464

It hardly seems to have gotten a mention elsewhere, but worthy of a shout on here I believe. Only been awarded three times previously.

Collectively, I would guess that most of us thought the press and other speculators were inacurate, premature, and unprofessional in the immediate post accident time frame.

That time has now passed.

“The system” should have provided some relevant information towards determining a cause. Over 600 similar airplanes are flying all over the world in all kinds of challenging conditions and, months later, we still have no concrete information on what caused this crash.

…….
Because the speed-brake on a 777 is located to the immediate left of the two throttle levers, …….

Which, I feel should be added, is true for just about every commercial jet in production and has been since.. who knows when.

It’s obvious, I know, but this is a good example of just how detailed, in depth and intense the investigations must be in situations like this. Weighing in numerous different variables and trying to find a cause for something that is previously unexplained.

Further AAIB Update now published

A further AAIB Special Bulletin on the incident has been issued in the last few days – full copy is available on the AAIB website (AAIB.gov.uk etc). It suggests they are now looking for an unusual combination of circumstances – i.e. nothing that happened during the flight had not been encountered on flights before, but maybe a previously un-encountered combination of multiple factors caused the problem.

The report suggests that restriction of fuel flow upstream of (i.e. flow of fuel to) the fuel pumps is still being investigated, both at Rolls Royce, and at Boeing.

Paul F

Report in the Telegraph – Cold Fuel being considered

http://www.telegraph.co.uk/news/1949763/Heathrow-crash-landing-%27could-have-been-caused-by-cold-weather%27.html

Not related at all.

From Flightglobal.com:

AA 777 engine incident: tests support ‘impeded throttle’ theory
By David Kaminski-Morrow

Preliminary investigations into last week’s throttle-response failure on an American Airlines Boeing 777-200ER suggest that a simple inadvertent obstruction of the throttle lever might have been responsible.

The aircraft had been approaching Los Angeles on 28 February, with its engines at flight-idle power and the auto-throttle engaged, when its left-hand powerplant apparently did not respond to a command for more thrust. Although the right-hand engine behaved normally, the left remained at flight-idle for 10-15 seconds before its thrust increased.

American’s incident came just six weeks after an identical British Airways aircraft crashed short of the runway at London Heathrow when both engines failed to respond to a thrust-increase command. Both carriers’ 777-200s are fitted with Rolls-Royce Trent 800 engines.

But a source familiar with the American inquiry says that, despite the parallels, initial findings suggest the two incidents are “very different”.

Crucially, flight-data recorder information from the American 777 – which includes the angle of the throttle levers – shows that the speed-brake was extended, and the left-hand throttle remained around the flight-idle position while the right-hand throttle moved forward.

Investigators have discovered no evidence of mechanical or fuel-related problems. But simulations and nearly three hours of flight tests, combined with information from the flight recorders and the crew, have turned up a potential explanation.

Because the speed-brake on a 777 is located to the immediate left of the two throttle levers, the first officer must reach over the throttles to activate it. The flight tests demonstrated that the first officer on the American Airlines flight might have unintentionally obstructed the left-hand throttle lever, preventing its moving forward when commanded by the auto-throttle.

Just 700g (1.5lb) of pressure would be enough to impede the throttle, and the resulting differential thrust would have initially been corrected by the autopilot, through the rudder, and by the aircraft’s thrust-asymmetry compensation system.

If the pilots were concentrating on the approach, says the source, the combination of these circumstances would have made the onset of the problem “almost unnoticeable” until the resulting yaw became significant.

Looks like American Airlines had an issue with an unresponsive engine on one of their 777s.

http://www.flightglobal.com/articles/2008/02/29/221923/american-investigates-as-777-engine-fails-to-respond-to-throttle.html

Who do you point the finger at Boeing or Rolls Royce

Its a couple of months since the last update regarding the incident. Has there been any news; either official, unofficial or anything in the Newspapers ?

Looks like American Airlines had an issue with an unresponsive engine on one of their 777s.

http://www.flightglobal.com/articles/2008/02/29/221923/american-investigates-as-777-engine-fails-to-respond-to-throttle.html

A wise man once said, if you eliminate all other possibilities, the remaining one, regardless how improbable must be the answer

Depends how you look at it, no the cause has not yet been confirmed, but a number of possible causes (ice in fuel etc) do appear to have been ruled out. This then helps focus the effort on the remaining options.

So, while it might seem a little backwards tackling it this way, every “possible” cause that can ruled out surely brings AAIB one step closer to finding the actual cause?

Paul F

So in short, we’re no closer to finding the reasons for the crash landing than we were an hour after it happened.

Sorry forgot to credit it…AirSafe.com

Where was that from, Steve? :confused:

The accident aircraft was a scheduled international flight from Beijing, China to London, England, and the flight was routine until about two miles from touchdown.

The engines would not respond to commands to increase thrust, and as a result the aircraft touched down about 1000 feet short of the runway.

There was a significant fuel leak, but no post-crash fire. All 136 passengers and 16 crew members were able to successfully evacuate the aircraft, and the most serious injury was a broken leg suffered by one passenger.

This latest AAIB update provided additional insights into the final moments before touchdown, the state of the fuel and fuel systems, and the condition of the engines and their associated control systems.

The damage caused by the landing gear had a direct role in the post crash fuel spill, and the report also showed how aircraft evacuation procedures contributed to the amount of fuel that spilled. Previous AAIB reports indicated that the engines did not respond to either autothrottle or autopilot commands shortly before landing. The latest report is a refinement of what was stated before.

The first officer took control for the landing at a height of approximately 780 feet, and shortly afterwards the autothrottles commanded an increase in thrust from both engines. The engines initially responded, but at a height of about 720 feet the thrust of the right engine reduced.

About seven 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 at less than the commanded thrust.

The engines failed to respond to further demands for increased thrust from the autothrottles, or from the manual inputs of the flight crew. The airspeed reduced as the autopilot attempted to maintain its intended glide slope angle, and by the time the aircraft had descended to about 200 feet above the ground, the airspeed had reduced to about 108 knots. The autopilot disconnected at about 175 feet, and afterwards the aircraft descended rapidly, contacting the ground just inside the airfield boundary fence and about 1,000 feet short of the runway.

During the flight, the aircraft traveled through high altitude regions of unusually low temperatures, with the crew changing altitudes at one point to fly through warmer air.

British weather authorities noted that although the temperature was unusually low, it was not exceptionally low.

During the flight, the fuel temperature dropped to as low as minus 34 degrees Celsius. However, an analysis of fuel samples taken after the accident showed that the freezing point of the fuel was much lower, at minus 57 degrees Celsius.

The fuel was tested by more than one laboratory, and initial results found that the fuel showed no signs of contamination or unusual levels of water.

This report made no mention of ice or slush forming in the fuel or fuel system during any portion of the flight.

Examination of the fuel tank revealed a loose connection in one of the fuel lines. Small pieces of debris were recovered in both the left and right main tank, and in two fuel pumps. Debris was also found in the left engine fuel oil heat exchanger (FOHE).

Detailed examination of both the left and right engine high pressure fuel pumps revealed signs of damage that could indicate that there was either a restriction in the fuel supply to the pumps or that there was an excessive aeration of the fuel. In spite of the damage, both pumps were found to be still being capable of delivering full fuel flow.

This update did not conclude what role, if any, that these fuel system anomalies played in the accident. An examination of the engines indicated no evidence of a mechanical defect. Also, there was no indication of ingestion of either birds or ice.

An examination of the data from the electronic engine controllers (EEC) and the quick access recorder (QAR) revealed no anomalies in the engine control system.

The electronic engine controllers and fuel metering valves were found to have responded correctly following the reduction in engine thrust.

During the impact and subsequent ground roll, the nose gear collapsed, the right main landing gear separated from the aircraft, and the left main landing gear was pushed up through the wing.

The right main landing gear ruptured the rear right wall of the center fuel tank and penetrated the cargo hold. The two front wheels of the right main landing gear broke away and struck the rear right fuselage, penetrating the cabin adjacent to rows 29 and 30.

Damage from the collapse of the left main landing gear left the crew unable to close the left spar valve, while damage from the right main gear limited the crew’s ability to close the right spar valve. Because of the way the evacuation procedure was executed, the crew could not close the right spar valve, and this contributed to the size of the fuel spill.

The evacuation checklist developed by Boeing for the 777 called for moving the fuel control switches to the cut-off position prior to operating the fire handles. This sequence would have allowed the crew of the accident aircraft to close the right spar valve in spite of the damage to the part of the electrical system that controlled that valve.

According the the AAIB report, a revised checklist from British Airways, for which Boeing had raised no technical objection, split the responsibility for moving the fuel control switches and operating the fire handles between the two flight crew members, and did not have any measure in place to ensure the correct sequence of actions.

During this accident, the fire control handle for the right engine was operated before the fuel control switch for that engine was moved to the cut-off position, keeping the spar valve in the open position and allowing fuel to escape.

AAIB noted that this situation was not causal to the accident but, could have had serious consequences in the event of a fire during the evacuation.

The AAIB recommended that Boeing notify all triple seven operators of the need to operate the fuel control switch to cut-off prior to operation of the fire handle, for both the fire drill and the evacuation drill, and to ensure that all versions of its checklists are consistent with this procedure.

I’d like to talk a bit about how the latest report addresses some of the more widely discussed possible causes of the accident.

There has been plenty of speculation about the causes of the accident by persons and organizations not connected to the accident investigation. One of the more prominent set of speculations was an article in the February 12, 2008 issue of the Wall Street Journal Online, which mentioned a buildup of ice crystals or slush in the fuel system as a possible cause of the engine thrust anomalies.

Nothing in the recent AAIB report directly supports that portion of the Wall Street Journal Online’s article. In fact, the AAIB has not found evidence of any significant water contamination, and also found that the the fuel stayed well above its freezing point throughout the flight.

The Wall Street Journal Online article also expressed doubts that there would be any safety recommendations released with the next update to the investigation. In fact, the report, which was released six days after the article was published, did have the safety recommendation concerning the emergency checklists.

These significant differences between the speculation of the Wall Street Journal Online and the update from the AAIB illustrate the difficulty that any outsider has when it comes to drawing conclusions about an investigation that is still in progress.

The suggestions made in previous AirSafe.com podcasts about how to evaluate what’s being published about this investigation are still valid and are worth repeating.

If you’re interested in following what is said about the investigation online or in the news media, keep this in mind: prior to the completion of the investigation by the AAIB, those outside of the investigation, including aviation safety experts and the largest news media organizations, will have access only to a fraction of the relevant information.

The AAIB will likely provide several more updates prior to publishing a final report, and these updates represent the most authoritative sources of information about the ongoing investigation.

Finally, take the time to read between the lines and to figure out what is fact and what is speculation. For additional information and other resources related to this investigation, please visit 777.airsafe.org.

I am also interested in the fact that after all the press hype of heroic piloting that the autopilot remained engaged (in fact it was never taken out but tripped itself out) until 175 feet at 108 knots after chasing the glideslope! With no available thrust selection the reality of the situation must be that the pilots had no discernable input into the resulting flightpath that followed.

I am appalled at the FOD(foreign object debris) found . The military have a strict FOD policy, why is this not being policed better at civilian level ?