AAIB initial report out on BA B777 crash at LHR
Mate have you seen what the IMPACT with the ground did to the Wheels?
It was a big impact to drive the Oleos up through the wing. The Rat is just behind the right wing and it probably "fell out" during the sudden impact Jolt.
Also the RAT's blades dont look very damageded.
As for the APU door open? Who knows? if one Engine had failed the crew may have had time to get it up and running ( it takes about 60 seconds to come up running ) If both failed at once at 600' then it would have Auto started and been "running" just as they hit the ground and no use at all.
But the photo shows Landing Lights "on" and NO RAT at 150', this means that one or both Transfer busses were powered at that time.
maybe the loss of power to the transfer busses as it hit the ground Auto started the APU and unlocked the RAT?
Basically with the Lts on and no RAT there had to be at least one of the three Jet Engines running ( Left Eng, Right Eng or APU )
It was a big impact to drive the Oleos up through the wing. The Rat is just behind the right wing and it probably "fell out" during the sudden impact Jolt.
Also the RAT's blades dont look very damageded.
As for the APU door open? Who knows? if one Engine had failed the crew may have had time to get it up and running ( it takes about 60 seconds to come up running ) If both failed at once at 600' then it would have Auto started and been "running" just as they hit the ground and no use at all.
But the photo shows Landing Lights "on" and NO RAT at 150', this means that one or both Transfer busses were powered at that time.
maybe the loss of power to the transfer busses as it hit the ground Auto started the APU and unlocked the RAT?
Basically with the Lts on and no RAT there had to be at least one of the three Jet Engines running ( Left Eng, Right Eng or APU )
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When you look at all the speculation as to the cause, you need to evaluate each hypothesis by first looking for one of two things:
1. Common Mode issues (multiple systems capable of being affected by a single event) - examples are catastrophic power failure, fuel (waxing, freezing or lack of), or a commanded / not commanded event)
2. Multiple single mode (coincidental) issues where two or more unrelated and unforseen events happen, neither in and of themselves capable of causing the failure but together they can.
I suppose there are even some root causes that belong to both categories. There was a software bug in the UK ATC system (the old one) that remained dormant for years until a particular set of circumstances on a particular day bought it to the surface.
Given the redundancy in the systems some of the postulated events just dont add up. Put this post in 'silly' if you like, but if everyone used the above as a reality check before sounding off it might help.
1. Common Mode issues (multiple systems capable of being affected by a single event) - examples are catastrophic power failure, fuel (waxing, freezing or lack of), or a commanded / not commanded event)
2. Multiple single mode (coincidental) issues where two or more unrelated and unforseen events happen, neither in and of themselves capable of causing the failure but together they can.
I suppose there are even some root causes that belong to both categories. There was a software bug in the UK ATC system (the old one) that remained dormant for years until a particular set of circumstances on a particular day bought it to the surface.
Given the redundancy in the systems some of the postulated events just dont add up. Put this post in 'silly' if you like, but if everyone used the above as a reality check before sounding off it might help.
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Idle speculation
I presume it is possible that something similar to the incident in Aug 05 near Malaysia involving accelerometer failure on a B777 may have happened insofar as if there were "hidden" failures already present in the aircraft, then the redundant systems or failsafes or whatever were the last line of defence and all it would take is one failure to cause a catastrophic incident?
http://www.atsb.gov.au/publications/...503722_001.pdf
Go easy on my theory, I'm NOT an expert, just an interested enthusiast.
http://www.atsb.gov.au/publications/...503722_001.pdf
Go easy on my theory, I'm NOT an expert, just an interested enthusiast.
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The left hand engine was stopped.
From these photos the left hand engine has fan damage and the right hand has not.
http://www.militaryphotos.net/forums...d.php?t=127323
http://www.militaryphotos.net/forums...d.php?t=127323
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Would a 777 endorsed pilot be able to advise if it is possible to confuse a double electrical failure with a double engine failure. If so I see this as a possible scenario that could end up creating what we saw with this aircraft.
The EICAS and intuitive electronic checklist will prioritise any faults, and helpfully name the fault and direct you to the appropriate checklist.
Comparing the 737 diagnostic process with the 777 is pointless - the 777 tells you what is wrong with it, in order of priority.
The initial AAIB report also says something interesting - THE ENGINES DID NOT FAIL!
Perhaps this is the moment for all those hundreds of people on here who claim to fly triplers (I just wonder how many of them are genuine?) - and those who profess to disliking journalists - and consider the Daily Mail to be the work of the devil - to avert their eyes.
Keeping Danny in Sandwiches
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For the problem to affect both engines it has to be either
1 Fuel
2 Ambient conditions - icing etc.
3 Software.
My guess is poor quality fuel out of Beijing, add cold soak during cruise and descent with blocked fuel filters restricting the amount of fuel to the engine. Now someone will tell me that they have fuel filter bypasses.
1 Fuel
2 Ambient conditions - icing etc.
3 Software.
My guess is poor quality fuel out of Beijing, add cold soak during cruise and descent with blocked fuel filters restricting the amount of fuel to the engine. Now someone will tell me that they have fuel filter bypasses.
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For the problem to affect both engines it has to be either
1 Fuel
2 Ambient conditions - icing etc.
3 Software.
1 Fuel
2 Ambient conditions - icing etc.
3 Software.
Last edited by alistairbailes; 22nd Jan 2008 at 20:08.
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For the problem to affect both engines it has to be either
1 Fuel
2 Ambient conditions - icing etc.
3 Software.
My guess is poor quality fuel out of Beijing, add cold soak during cruise and descent with blocked fuel filters restricting the amount of fuel to the engine. Now someone will tell me that they have fuel filter bypasses.
1 Fuel
2 Ambient conditions - icing etc.
3 Software.
My guess is poor quality fuel out of Beijing, add cold soak during cruise and descent with blocked fuel filters restricting the amount of fuel to the engine. Now someone will tell me that they have fuel filter bypasses.
sky mate - read the rest of the thread(s) it might save you the trouble of "guessing".
Better still, wait for the full AAIB report and you won't have to guess at all!
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Just to sum up items noticed from the Daily Mail photgraphs, including a couple of items not mentioned yet.
1. Nose gear landing lights are on (from the approach photo)
2. Wing root landing lights are on (from the approach photo)
3. The RAT is not deployed (from the approach photo)
4. The APU inlet door is not open (from the ground impact photo)
1. Nose gear landing lights are on (from the approach photo)
2. Wing root landing lights are on (from the approach photo)
3. The RAT is not deployed (from the approach photo)
4. The APU inlet door is not open (from the ground impact photo)
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Only one engine running!
interesting all these speculations, however, maybe the engines were running but not at the required power settings, you will go down too.
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I didn't say it was producing power, simply that it was rotating.
The previous post seemed to suggest that no evidence of damage was evidence of not running.
It both engines were rotating then is it not possible that both engines were similarly vulnerable to blade damage - powered or not - but that blade damage would depend on the nature of the damage instrument.
One engine has evidence of soil spread around its fan; the other has a heap of soil piled in the lower fan segment.
I am simply making observations from the photographs not drawing any conclusions that it for you experts.
The previous post seemed to suggest that no evidence of damage was evidence of not running.
It both engines were rotating then is it not possible that both engines were similarly vulnerable to blade damage - powered or not - but that blade damage would depend on the nature of the damage instrument.
One engine has evidence of soil spread around its fan; the other has a heap of soil piled in the lower fan segment.
I am simply making observations from the photographs not drawing any conclusions that it for you experts.
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FAA AD AD 99-27-15 of 11 Jan 2000 (link) a situation applicable to GE engines on the 777 addressed a known fault
"....applicable to certain General Electric Company GE90 series turbofan engines. This action requires visually inspecting Ps3 and P3B sense lines and full authority digital engine control (FADEC) Ps3 and P3B sensing ports and fittings, cleaning Ps3 and P3B fittings and sensing ports, purging the Ps3 and P3B systems of moisture, and, if necessary, blending of high metal, nicks, burrs, or scratches on Ps3 and P3B fitting threads. This amendment is prompted by seven reports of loss of thrust control due to corruption of the signals to the FADEC caused by water freezing in the Ps3 sensing system. The actions specified in this AD are intended to prevent loss of thrust control due to corruption of the Ps3 and P3B signals to the FADEC which if it occurs in a critical phase of flight, could result in loss of aircraft control."
.
It's not beyond credibility to see that the same situation could apply to the air and fuel pressure reference lines in the FADEC(s) attached to an RR Trent engine - as pointed out at:
.
http://tinyurl.com/2nx3ym
.
"....applicable to certain General Electric Company GE90 series turbofan engines. This action requires visually inspecting Ps3 and P3B sense lines and full authority digital engine control (FADEC) Ps3 and P3B sensing ports and fittings, cleaning Ps3 and P3B fittings and sensing ports, purging the Ps3 and P3B systems of moisture, and, if necessary, blending of high metal, nicks, burrs, or scratches on Ps3 and P3B fitting threads. This amendment is prompted by seven reports of loss of thrust control due to corruption of the signals to the FADEC caused by water freezing in the Ps3 sensing system. The actions specified in this AD are intended to prevent loss of thrust control due to corruption of the Ps3 and P3B signals to the FADEC which if it occurs in a critical phase of flight, could result in loss of aircraft control."
.
It's not beyond credibility to see that the same situation could apply to the air and fuel pressure reference lines in the FADEC(s) attached to an RR Trent engine - as pointed out at:
.
http://tinyurl.com/2nx3ym
.
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Has anyone commented on this? I haven't noticed it. In today's Daily Telegraph there is a letter suggesting exactly this and that all cell phone logs and laptops should be recalled and checked to see if they were operating.
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The problem with P30 icing on R-R engines has been known and compensated for at least since the RB211 FAFC equipped units. I can see no reason why Trents are not similarly fitted.
Even if P30 is lost the FADEC will fail to reversionary mode using speed and temperature rather then EPR as the main control parameters.
I am not allowed to speculate further.
VnV
Even if P30 is lost the FADEC will fail to reversionary mode using speed and temperature rather then EPR as the main control parameters.
I am not allowed to speculate further.
VnV
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c.40 seconds is the figure that is appearing most...
or more precisely if they were doing 140kts at 2 miles it would have been 51 seconds to the runway.
or more precisely if they were doing 140kts at 2 miles it would have been 51 seconds to the runway.
777 Ops
As a current 777 pilot, I am obviously concerned about any UNEXPLAINED accident, and believe that for the most part this and the previous thread has produced a useful discussion.
Its been difficult to assimilate all the unanswered, misleading and incorrect quotes before my reply so apologies if this duplicates earlier posts.
FACTS
AAIB reports that the engines 'did not respond' - this does not imply they were still running OR that they had failed, that will be answered in a later report. [The AAIB report into Kegworth gave detailed engine parameters at all relevant stages of flight.]
The RAT is visible in the post 'landing' photos. From these I am not able to determine whether it had been deployed or not. Discussions with a 777 engineer result in speculation that it was deployed [it would have been contained in the fuselage otherwise. The right wing/engine geometry may have prevented a deployed RAT from being torn away during impact].
The APU door is open, this does not imply that the APU was running at any stage that may have been relevant.
The Captain is reported to have stated that all power and avionics were lost.
No passengers reported any loss of lighting/facilities prior to landing [- is this a fact or a lack of one?]
Passengers reported increased engine noise.
PROCEDURE
Recall actions for Dual Eng Fail/Stall are applicable when "engine speed for both engines is below idle"
These actions include manually deploying the RAT and starting the APU.
In flight, the RAT will deploy automatically if:
-both engines are failed and center hydraulic pressure is low
-both AC transfer buses are unpowered or
-all three hydraulic system pressures are low.
In flight the APU will start automatically when both transfer buses are unpowered.
At 190 tons Vref30 is approximately 132 & Vref25 is 138. [With nil wind 2nm will be covered in approximately 50 sec at these speeds].
CAUSE - OPTIONS
1.Flown into ground (mishandled)
2.Thrown into ground (eg windshear)
3.'Knocked' to ground (eg birds)
4.Fell to ground (loss of thrust etc)
CONCLUSIONS
IF the rate of descent was allowed to double [due to loss of thrust] the crew would have about 25 seconds until contact.
'Dual Engine Failure' (as defined above) will result in loss of thrust and most flightdeck displays until electrical power is restored. This fits the description attributed to the Captain. Apparent position of RAT/APU door lends support to this theory.
IF recall actions had been completed promptly, it is possible that one or both engines may have restarted prior to impact.
PURE SPECULATION
I believe that only option 4 above is feasible, obviously 'WHY?' is going to take a while. The crew had an indication of a dual loss of thrust, probably dual engine fail, resulting in numerous EICAS alerts, loss of flight displays AND very little time to effect a recovery.
They were very lucky to walk away [not disputing the skill involved].
CONCERN
My last 4 approaches [from 1500' - 300'] we would not have had a chance at making any clear area.
Until a prime cause of the loss of thrust is determined there is a probability of a re-occurrence. Still no AD issued on this?
QUESTIONS
Was flap setting changed prior to touchdown - any simulations to indicate effectiveness at prolonging the glide?
Confirm BA SOP is F25 @ LHR?
Confirm BA/777 fleet stabilisation criteria, and usual method of handling '160 til 4' [On the -300 with Vref 149, we start reducing at about 6 miles and are normally within a couple of knots of the assignment.]
[Please fell free to PM me if you are concerned about confidentiality.]
Its been difficult to assimilate all the unanswered, misleading and incorrect quotes before my reply so apologies if this duplicates earlier posts.
FACTS
AAIB reports that the engines 'did not respond' - this does not imply they were still running OR that they had failed, that will be answered in a later report. [The AAIB report into Kegworth gave detailed engine parameters at all relevant stages of flight.]
The RAT is visible in the post 'landing' photos. From these I am not able to determine whether it had been deployed or not. Discussions with a 777 engineer result in speculation that it was deployed [it would have been contained in the fuselage otherwise. The right wing/engine geometry may have prevented a deployed RAT from being torn away during impact].
The APU door is open, this does not imply that the APU was running at any stage that may have been relevant.
The Captain is reported to have stated that all power and avionics were lost.
No passengers reported any loss of lighting/facilities prior to landing [- is this a fact or a lack of one?]
Passengers reported increased engine noise.
PROCEDURE
Recall actions for Dual Eng Fail/Stall are applicable when "engine speed for both engines is below idle"
These actions include manually deploying the RAT and starting the APU.
In flight, the RAT will deploy automatically if:
-both engines are failed and center hydraulic pressure is low
-both AC transfer buses are unpowered or
-all three hydraulic system pressures are low.
In flight the APU will start automatically when both transfer buses are unpowered.
At 190 tons Vref30 is approximately 132 & Vref25 is 138. [With nil wind 2nm will be covered in approximately 50 sec at these speeds].
CAUSE - OPTIONS
1.Flown into ground (mishandled)
2.Thrown into ground (eg windshear)
3.'Knocked' to ground (eg birds)
4.Fell to ground (loss of thrust etc)
CONCLUSIONS
IF the rate of descent was allowed to double [due to loss of thrust] the crew would have about 25 seconds until contact.
'Dual Engine Failure' (as defined above) will result in loss of thrust and most flightdeck displays until electrical power is restored. This fits the description attributed to the Captain. Apparent position of RAT/APU door lends support to this theory.
IF recall actions had been completed promptly, it is possible that one or both engines may have restarted prior to impact.
PURE SPECULATION
I believe that only option 4 above is feasible, obviously 'WHY?' is going to take a while. The crew had an indication of a dual loss of thrust, probably dual engine fail, resulting in numerous EICAS alerts, loss of flight displays AND very little time to effect a recovery.
They were very lucky to walk away [not disputing the skill involved].
CONCERN
My last 4 approaches [from 1500' - 300'] we would not have had a chance at making any clear area.
Until a prime cause of the loss of thrust is determined there is a probability of a re-occurrence. Still no AD issued on this?
QUESTIONS
Was flap setting changed prior to touchdown - any simulations to indicate effectiveness at prolonging the glide?
Confirm BA SOP is F25 @ LHR?
Confirm BA/777 fleet stabilisation criteria, and usual method of handling '160 til 4' [On the -300 with Vref 149, we start reducing at about 6 miles and are normally within a couple of knots of the assignment.]
[Please fell free to PM me if you are concerned about confidentiality.]
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Impact Trail
Stitched together from vid-caps of footage taken from helicopter that was moving forward and then up. I adjusted perspective of each as best I could:
-=MachacA=-
-=MachacA=-