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BA 777 Off Runway At LHR - Part 8  
User currently offlineSrbmod From , joined Dec 1969, posts, RR:
Posted (6 years 7 months 3 weeks 6 days 1 hour ago) and read 39264 times:

Continuing the discussion from this thread:

BA 777 Off Runway At LHR - Part 7 (by Srbmod Jan 21 2008 in Civil Aviation)

256 replies: All unread, showing first 25:
 
User currently offlinePetera380 From United States of America, joined Feb 2005, 350 posts, RR: 0
Reply 1, posted (6 years 7 months 3 weeks 6 days 1 hour ago) and read 39292 times:
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Can't see to find any pictures of the aircraft being moved to its new resting place?

Peter


User currently offlineBeefmoney From United States of America, joined Oct 2000, 1116 posts, RR: 4
Reply 2, posted (6 years 7 months 3 weeks 6 days ago) and read 39240 times:

I'll just restate my post here since it was the last one in part 7.
Earlier in the threads, someone posted a video of the landing, but it was removed from youtube before I was able to see it. Has anyone been able to find that video elsewhere since then? I somewhat remember someone mentioning that they saw the APU inlet open (before impact) on the video.


User currently offlineTdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 79
Reply 3, posted (6 years 7 months 3 weeks 6 days ago) and read 39194 times:



Quoting Beefmoney (Reply 3):
I somewhat remember someone mentioning that they saw the APU inlet open (before impact) on the video.

It was certainly open after impact; there are unconfirmed reports that it was open pre-impact. The most recent investigation update stated that both engines were running above idle with no electrical power loss, so there's no pressing reason for the APU to have been turned on by the aircraft or flight crew.

Tom.


User currently offlineBeefmoney From United States of America, joined Oct 2000, 1116 posts, RR: 4
Reply 4, posted (6 years 7 months 3 weeks 6 days ago) and read 39163 times:



Quoting Tdscanuck (Reply 4):
The most recent investigation update stated that both engines were running above idle with no electrical power loss, so there's no pressing reason for the APU to have been turned on by the aircraft or flight crew.

I agree, and that's why trying to find the video has kept my interest. Only because it would allow me to see if that person was correct in stating that they saw the APU inlet open. I can't imagine why it would be, but I can't really rule it out unless I can see the video.


User currently offlineTangowhisky From United States of America, joined Jun 2006, 926 posts, RR: 7
Reply 5, posted (6 years 7 months 3 weeks 5 days 23 hours ago) and read 38855 times:

This just in from Flight

Investigators have determined that the British Airways Boeing 777-200ER which crashed on approach to London Heathrow last week had adequate fuel on board and that both engines continued to generate thrust, albeit much-reduced, during the event.

Preliminary findings from the Air Accidents Investigation Branch had indicated that the aircraft’s Rolls-Royce Trent 800 engines had failed to respond to an auto-throttle command for increased thrust during the final stage of the approach.

In a newly-issued update, however, the AAIB says both engines did initially respond to the auto-throttle command, but that the starboard engine’s thrust reduced after about 3s and the port engine’s thrust also reduced to a similar level 8s later.

“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,” it adds.

Data from the flight recorders, says the AAIB, shows that an “adequate” fuel quantity was on board the twin-jet and that both the auto-throttle and engine-control commands were performing as expected, both before and after the thrust reduction.

“All possible scenarios that could explain the thrust reduction and continued lack of response of the engines to throttle-lever inputs are being examined,” it adds.

It states that the analysis includes examination of the fuel-flow path between the 777’s fuel tanks and the engine fuel nozzles.



Only the paranoid survive
User currently offlineFlyASAGuy2005 From United States of America, joined Sep 2007, 7004 posts, RR: 11
Reply 6, posted (6 years 7 months 3 weeks 5 days 23 hours ago) and read 38581 times:



Quoting Tangowhisky (Reply 6):

Interesting. So this is telling me that maybe we have a computer glitch? No, yes? I may be way off considering this thread has gone on for so long and is too much to read though.



What gets measured gets done.
User currently offlineAerobalance From United States of America, joined Sep 2000, 4682 posts, RR: 46
Reply 7, posted (6 years 7 months 3 weeks 5 days 22 hours ago) and read 38407 times:



Quoting FlyASAGuy2005 (Reply 8):
So this is telling me that maybe we have a computer glitch? No, yes?

Possible Computer glitch - hardware or software.
Possible Fuel contamination issue.
Possible Fuel system components issue.
Others?



"Sing a song, play guitar, make it snappy..."
User currently offlineGlbltrvlr From United States of America, joined Oct 2007, 729 posts, RR: 0
Reply 8, posted (6 years 7 months 3 weeks 5 days 22 hours ago) and read 38394 times:



Quoting FlyASAGuy2005 (Reply 8):
Interesting. So this is telling me that maybe we have a computer glitch? No, yes?

Not the way I read it.

Quote:
the auto-throttle and engine-control commands were performing as expected, both before and after the thrust reduction

and

Quote:
...analysis includes examination of the fuel-flow path between the 777’s fuel tanks and the engine fuel nozzles



User currently offlineKhobar From United States of America, joined Mar 2006, 2379 posts, RR: 3
Reply 9, posted (6 years 7 months 3 weeks 5 days 22 hours ago) and read 38333 times:



Quoting Tangowhisky (Reply 6):
Investigators have determined that the British Airways Boeing 777-200ER which crashed on approach to London Heathrow last week had adequate fuel on board and that both engines continued to generate thrust, albeit much-reduced, during the event.

The AAIB didn't say anything about "much reduced", only that it was "less than the commanded thrust."


User currently offlineZeke From Hong Kong, joined Dec 2006, 9097 posts, RR: 75
Reply 10, posted (6 years 7 months 3 weeks 5 days 22 hours ago) and read 38107 times:



Quoting Tdscanuck (Reply 4):
The most recent investigation update stated that both engines were running above idle with no electrical power loss, so there's no pressing reason for the APU to have been turned on by the aircraft or flight crew.

Tom I have seen nothing form the AAIB that says there was no electrical power loss, given their "focus" now it looks like they are leaning towards a N609UA type scenario.



We are addicted to our thoughts. We cannot change anything if we cannot change our thinking – Santosh Kalwar
User currently offlineLeezyjet From United Kingdom, joined Oct 2001, 4042 posts, RR: 53
Reply 11, posted (6 years 7 months 3 weeks 5 days 22 hours ago) and read 38005 times:



Quote:
Pprune is still closed to non-members btw! What is going on over there at Pprune Towers?

Sign up then, it's free. They have restricted access to members only as the link to their site was published in quite a few articles about the BA accident and their servers have been melting as a result of non members just having a look !!.

 Smile



"She Rolls, 45 knots, 90, 135, nose comes up to 20 degrees, she's airborne - She flies, Concorde Flies"
User currently offlineTUIflyer From United Kingdom, joined Jan 2008, 206 posts, RR: 0
Reply 12, posted (6 years 7 months 3 weeks 5 days 21 hours ago) and read 37994 times:

'Investigators examining the causes of the Boeing 777 that crashed on approach to Heathrow last week have determined that the aircraft had adequate fuel onboard and that engines continued to generate thrust, although much reduced. Initial findings from the Air Accidents Investigation Branch has indicated the aircrafts Trent 800 engines had failed to respond to an auto-throttle command for increased thrust.'

An interesting development, was this expected or is this a surprise? Could this effect the whole 777 fleet or just the Trent engines?

http://letsfindaflight.com/page_1181845192626.html

TUIflyer



Don't just travel, travel with a smile. . .
User currently offlineMop357 From United States of America, joined Mar 2007, 85 posts, RR: 0
Reply 13, posted (6 years 7 months 3 weeks 5 days 21 hours ago) and read 37920 times:



Quoting Aerobalance (Reply 9):
Possible Computer glitch - hardware or software.
Possible Fuel contamination issue.
Possible Fuel system components issue.
Others?

Thanks for keeping it short and simple

Quoting Glbltrvlr (Reply 10):
Quoting FlyASAGuy2005 (Reply 8):
Interesting. So this is telling me that maybe we have a computer glitch? No, yes?

Not the way I read it.

Well if the engine thrust responded at first and then reduced after 3 and 8 seconds then that sounds like it maybe a computer glitch


User currently offlineLTBEWR From United States of America, joined Jan 2004, 13113 posts, RR: 12
Reply 14, posted (6 years 7 months 3 weeks 5 days 21 hours ago) and read 37900 times:

Could there have been a damaged or faulty sensor that gave bad info to the computer to use that set up the problem?
As noted in some posts, the cruising altitude temptatue outside the a/c could have been much colder than normal, perhaps causing icing and in turn cause a false reading or damaging a critical sensor. You also could have had a critical sensor just failing as nothing is fail-safe, although it is hoped there is enough reduntancy in the systems to reduce faults.


User currently offlineDBCC From Switzerland, joined Nov 2007, 65 posts, RR: 0
Reply 15, posted (6 years 7 months 3 weeks 5 days 20 hours ago) and read 37583 times:

So, they had a engine rollback. Cause could be one of many things, but someone better find the problem sooner than later.

What Is An Engine Rollback (by Dreampilot Dec 31 2006 in Tech Ops)


User currently offlineComairguycvg From United States of America, joined Jan 2006, 337 posts, RR: 1
Reply 16, posted (6 years 7 months 3 weeks 5 days 20 hours ago) and read 37254 times:



Quoting PW100 (Reply 13):
Not sure if this is correct, however it could explain why the APU door was open, it then does not necessarily mean that the APU was running or even in start-up sequence.

The FDR will tell the story if it was on or not.


User currently offlineAyubogg From UK - Scotland, joined Mar 2007, 218 posts, RR: 0
Reply 17, posted (6 years 7 months 3 weeks 5 days 20 hours ago) and read 37189 times:



Quoting Beefmoney (Reply 3):
Earlier in the threads, someone posted a video of the landing, but it was removed from youtube before I was able to see it. Has anyone been able to find that video elsewhere since then?

Is there really a video of the actual crash-landing out there? The odds of someone with a video camera taping 27L at the moment are kinda astronomical, aren't they? Well, if there is one, someone needs to re-post it and share it with everyone!

Regards,
-Ayubogg



Alba gu bràth
User currently offlineTdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 79
Reply 18, posted (6 years 7 months 3 weeks 5 days 20 hours ago) and read 37031 times:



Quoting FlyASAGuy2005 (Reply 8):
So this is telling me that maybe we have a computer glitch? No, yes?

It tends to point away from an aircraft computer glitch, although nothing is certain. The fact that the engines tried to respond says that they got the signal from the thrust levers, which implies an intact communication path to the EEC. If they then rolled back either the airplane changed the command without any input from the thrust levers (odd) or the EEC decided to do something based on some piece of data. In my head, this leans towards software in the EEC or bad sensor data (could be airplane or engine), but those are just possibilities, nothing certain.

Quoting Zeke (Reply 12):
Tom I have seen nothing form the AAIB that says there was no electrical power loss

They haven't explicitly stated it but there have been no confirmed reports from anywhere, other than the initial first-hours-after-the-event-third-hand-report of "lost power", of electrical power loss. It's very conspicuous by its absence, especially given confirmation that the engines were running above idle.

Quoting LTBEWR (Reply 17):
You also could have had a critical sensor just failing as nothing is fail-safe, although it is hoped there is enough reduntancy in the systems to reduce faults.

Lots of things are fail-safe, including air data sensors.

Tom.


User currently offlineDc863 From Denmark, joined Jun 1999, 1558 posts, RR: 2
Reply 19, posted (6 years 7 months 3 weeks 5 days 20 hours ago) and read 36882 times:

What if the fuel sump pumps were exposed during final. I know that SOP for go arounds during low fuel status says to apply power slowly and not to pitch the nose up beyond a certain degree.

User currently offlineTangowhisky From United States of America, joined Jun 2006, 926 posts, RR: 7
Reply 20, posted (6 years 7 months 3 weeks 5 days 20 hours ago) and read 36833 times:

The EEC or FADEC computes a target N1 from the thrust levers, sensors, etc. I wonder what it was computing when the thrust levers were pushed forward. This is available in the FDR. If the command N1 went up and then went back down, then it is a sensor/software related error, and fuel issues can be ruled out. So, what was the N1 being commanded by the FADEC while the thrust levers were pushed forward? They must have this info by now.


Only the paranoid survive
User currently offlineGlideslope From United States of America, joined May 2004, 1617 posts, RR: 0
Reply 21, posted (6 years 7 months 3 weeks 5 days 20 hours ago) and read 36688 times:



Quoting Dc863 (Reply 22):



Quoting Dc863 (Reply 22):
What if the fuel sump pumps were exposed during final. I know that SOP for go arounds during low fuel status says to apply power slowly and not to pitch the nose up beyond a certain degree.

My understanding is there was quite a steep bank on the line up to 27 on a short final. Lot's of unknowns.



To know your Enemy, you must become your Enemy.” Sun Tzu
User currently offlineKmh1956 From Bermuda, joined Jun 2005, 3324 posts, RR: 7
Reply 22, posted (6 years 7 months 3 weeks 5 days 19 hours ago) and read 36608 times:

Whatever the cause of this accident, after hearing about the actions of the flight crew it has made me even more determined that I WILL fly BA; I WILL fly the 777; and I hope to hell that one day I get to fly with this particular captain.


'Somebody tell me why I'm on my own if there's a soulmate for everyone' :Natasha Bedingfield
User currently offlineBearste From United States of America, joined Sep 2007, 14 posts, RR: 0
Reply 23, posted (6 years 7 months 3 weeks 5 days 19 hours ago) and read 36586 times:

Quoting Kmh1956 (Reply 25):
I hope to hell that one day I get to fly with this particular captain

I'm sure you do!

Like Licorice????

http://www.newsoftheworld.co.uk/2001_hero_pilot_romp.shtml

[Edited 2008-01-24 16:43:11]

User currently offlineKmh1956 From Bermuda, joined Jun 2005, 3324 posts, RR: 7
Reply 24, posted (6 years 7 months 3 weeks 5 days 19 hours ago) and read 36177 times:



Quoting Bearste (Reply 27):
http://www.newsoftheworld.co.uk/2001_hero_pilot_romp.shtml

Now THERE'S a reliable news source....



'Somebody tell me why I'm on my own if there's a soulmate for everyone' :Natasha Bedingfield
25 CALPSAFltSkeds : Since the fuel on board hasn't been stated, could it have been low enough that the steep bank got the engines sucking air instead of fuel? One wonder
26 Tangowhisky : Doubt it. Engines would have flamed out.
27 Post contains images JMULAH : Geez... i think we need more threads in this topic!
28 Dc863 : Speaking about out of fuel, did Avianca 052 have any engines running prior to impact? I believe all 4 were out.
29 Starlionblue : They were all out. But that an out of fuel situation due mostly to crew error. They left themselves too little fuel to even reach their alternate, a
30 Post contains images Brucek : Assuming that by now they know WHAT happened, is it standard practice to to not release any data until they know WHY, and the affected party ( Boeing
31 Starlionblue : Even if they don't have an explanation, there's no need to ground the aircraft. That's done if "they"'re really worried this could happen again. I do
32 Etops1 : damn those pics of that captain on his layovers are very incriminating. if there is one rule about layover parties it's "no pictures or videos" becaus
33 CoolGuy : So just to recap, at the moment there is no other news since the initial report, right? (btw I am taking a BA 777 JFK-LHR coming up to visit the grand
34 CBPhoto : After reading through 8 pages of the event that occurred at LHR, I can come to only one conclusion at this point. In this day and age where airline pi
35 Post contains images JetMech : LOL, what a funny set of pictures! Perhaps the fuel shut off levers where struck to the off position by the forceful ejection of a long forgotten pie
36 RebelDJ : Well, there is an update to the initial report on the AAIB website (http://www.aaib.dft.gov.uk/latest_news/accident_to_boeing_777_236__g_ymmm__at_hea
37 Post contains links QantasHeavy : Sorry if this link has already been posted. I think this gives a very good summary and is well-written. No "Boeing DC-1011s air buses" mention and it
38 Max777geek : Everyone talking about APU looks like forgetting it takes a while to start it, the whole stuff drop-to-crash isn't been so long to start the APU, it
39 PhilSquares : Very easy! When fuel gets close to it's freezing point, ice crystals (from bad fuel, accumulation in the tank from condensation, there are several wa
40 Max777geek : The fuel that did not freeze at cruise level at -80C did get close to freezing point at sea level, without jamming pumps, pressure sensors, and block
41 Mandala499 : And for the arguers of moving thrust levers in autothrottles (the ones who don't like the Bus), heck, disengage A/T or just go to TOGA and see if it
42 Post contains images Starlionblue : Isn't that a bit contradictory? True. You're assuming that the fuel magically heats up to ambient temperature during the descent from cruise to sea l
43 Max777geek : one lump in one engine I may understand, but two at the same time ? also I think there are sensors around the fuel lines in order to avoid this kind
44 AF1624 : The temperature at cruise level is not -80°C. It's around -55°C to -45°C SAT (saturated air temperature) depending on FL and region. Due to the vi
45 AF1624 : Well, actually, it kinda does. And I might add that the fuel heats very quickly when the aircraft descends because the air becomes thicker and thicke
46 NEMA : I,m Surprised that one of the threads didnt link tothe bbc video which showed the full process of it being moved in a speeded up film. Probably laste
47 PhilSquares : Hmm, let's see. One fuel truck, or fuel pit, same fuel goes into all tanks....you figure it out! No one has said the thrust levers were blocked. In f
48 Post contains links Carduelis : Below is a 'copy' of an earlier posting which may or may not link - there were at least two . . . Removal of aircraft v e r y slowly, so this is spee
49 Max777geek : Sorry, my english. I did think for lump it was intended "one" quantity of more dense fuel. this would make me think to the electronic, not to the fue
50 SEPilot : That should have absolutely zero effect as long as it was coordinated.
51 Starlionblue : Well, the wings are symmetrical so hypothetical you could get one lump per wing tank. Purely hypothetical at this point of course. Of course there ar
52 Moo : I personally have my doubts that any fuel contamination effects would manifest in two different engines fed by two different fuel tanks within second
53 Post contains links NAV20 : Max777geek, that was my own impression at first - but that was when the reports said that both engines 'failed to respond.' On the basis of the lates
54 AF1624 : Thanks, I stand corrected. I thought it was "saturated" and not "static" which obviously makes more sense. I do agree. But as the fuel is not frozen
55 PhilSquares : I repeat, the auto-throttle system did what it was expected to do. It commanded more thrust when it sensed a requirement existed for more thrust. The
56 Max777geek : I guess in this case the concentration of the fuel would be different, both for the presence of water and for the increased density. This should be r
57 PhilSquares : And my point was the fuel is coming out of one common source on the ground. If there was a problem with the fuel why wouldn't it be in all the tanks?
58 Tangowhisky : My guess is that both FADECs went to fail safe mode by commanding both engines to go to COMMAND IDLE due to dual failed throttle sensors. If both thro
59 Checksixx : Thought that was what Carb Heat was for....
60 Khobar : So you were seeing -72C, or -42C RAT, yes? -52C, in this particular case.
61 PhilSquares : Yes....very cold
62 Bellerophon : Khobar ...-52C, in this particular case... Not correct. AF1624 ...And by the way, what's the freezing temperature for JET-A fuel ?... -40°C ...Or wha
63 Starlionblue : I would tend to think so too. I was just hypothesizing. However I'm in no way an expert. It might freeze anyway. The fuel is not one homogenous mass
64 AF1624 : But then, does that happen often ? Freezing fuel I mean ?
65 Tdscanuck : Not unless you had an incredibly uncoordinated turn. The passengers certainly would have noticed that. If you're turning uncoordinated, no. The pump
66 Post contains links Khobar : Actually, it is correct. "Jet A (US) has a higher freeze point than Jet A-1 (i.e. it freezes more readily). The current spec for the UK is what used
67 Post contains images Bellerophon : Starlionblue The fuel is not one homogenous mass...some parts of the plane are colder than others...tanks have all sorts of nooks and crannies...we ca
68 Khobar : Blackbird?
69 Bellerophon : Khobar Question: ...what's the freezing temperature for JET-A fuel ?... Answer: ...-52C, in this particular case... AF1624 asked about JET A fuel (not
70 Post contains images David L : Not quite but close, I suspect.
71 AF1624 : Concorde ?
72 Post contains images Leezyjet : Check out the 2 pics in Capt Bellerophon's profile for a clue..........
73 Mandala499 : What I'm about to write maybe worthless, but it's just a thought. As Phil said... The fuel will be at near homogeneity throughout the aircraft for suc
74 Moo : That still doesn't explain an almost synchronised affect on both engines - yes, both engines could have been affected by contaminated fuel from a sin
75 Tangowhisky : I hope the investigators will tell us soon what the EPR CMD (command) was when the throttles were pushed up. If they were commanding (computing) the
76 RIXrat : Assuming that this could have happened, and I'm going on assumptions now, just like everyone else, in human terms it could mean that the patient suff
77 Moo : Planes are symmetric to within tolerances. Thats the key here - aircraft and aircraft parts are built to within a certain tolerance, and thus are by
78 Post contains images Mandala499 : Honestly, I would bet the same too. I'm just asking if it is plausible... not asking if that's what happened or if that was likely to have happened.
79 Tdscanuck : Why wouldn't you know? EICAS shows the fuel temperature right below the total fuel quantity. Same thing. The thickness of the main fuel tank is the t
80 Post contains links Khobar : He qualified his question with "Or whatever fuel airliners use today ?" Hence my answer which I pointed out was "in this particular case" being relev
81 Tdscanuck : If something floating on the fuel got into the lines, it means they ran out of fuel (the only time the surface of the fuel should meet the pump inlet
82 Post contains links Khobar : "This results from partial freezing, and pilots say the outside air temperature at some altitudes en route to the UK was down to minus 70 degrees tha
83 ScrubbsYWG : i realize that it is probably designed to cool the oil, but by conservation of energy laws, if it is cooling the oil, the fuel is being heated at the
84 Post contains images JetMech : G'day Tom, I thought I might add some further points to the discussion. Possibly. Most of the fuel tanks I have been in are baffled by the ribs. The r
85 Yanqui67 : You are wrong, the oil is cooled and the fuel "IS" heated. The main pourpse of the heated fuel coming from the oil/fuel heat exchanger is to prevent
86 Post contains links Starglider : Hi Tom, The B777 apparently has one heat exchanger in the left wing tank and has two heat exchangers in the right wing tank. Because the left wing ta
87 TristarSteve : The heat exchangers in the fuel tanks on the B777 (and other Boeings are the same) are there to cool the case drain hydraulic oil. (Oil that is used
88 Starglider : Correct, i should not have used the term fuel heating but they do influence fuel temperature when fuel flows through the oil-to-fuel heat exchangers
89 Queso : If the turn is coordinated properly, all of the G-force should remain in the "down" direction with reference to the vertical axis of the airframe reg
90 Valkyrie01 : I wonder what kind of EICAS message if any did the crew got. As far as the engine spooling up and spooling back down. I am thinking Air and Fuel. Air
91 Movingtin : I have to strongly disagree! they have a real good idea what happened. If Not, the type would have been grounded until they found an explanation. Do
92 Aaresl : By "baffled by ribs" you mean ribs from left to right and also from front to back, like a grid? But where is the bottom-most point then? In different
93 TristarSteve : This is very basically for a B777, dihedral wing, one tank in each wing, not aerobatic!. The ribs in a wing run fore and aft. There are a lot of them
94 Post contains images Aaresl : Thank you for very educating answer! After reading your post I feel a little stupid for even asking such a question. Of course there is logical and s
95 Huxrules : I'm curious- wouldn't there be some kind of error (possibly displayed on the EICAS) if the FADEC commended the engine to spool up and then did not mee
96 Post contains images Leezyjet : Amazing, after 8 parts and around 1,000 posts, we are finally getting somewhere close to having an informed discussion by reasonably well informed peo
97 Starlionblue : Blackbird?[/quote] Tdscanuck said "if you don't have an explanation". You want to ground the type because of something. In other words in your hypothe
98 Movingtin : my point is the aviation authorities did NOT see a design flaw which would allow 4 computers with independant sensors all fail at once. they have had
99 Mandala499 : Was it out? I didn't see it... It has happened before, especially at low power settings. I saw the fan blade damage on a CFM56 on a similar kind of "
100 JetMech : Yes of course, I forgot that you can co-ordinated a turn no matter how steep the bank angle. Nice catch! One situation where you may get un-coordinat
101 Starlionblue : I would tend to agree. But I'm not an expert. They could do that. Then again I doubt the investigators want to release information piecemeal. It woul
102 HAWK21M : I thought Pics showed the RAT in damaged & retracted position. regds MEL
103 B777ER : Without bothering to read through 8 bloody threads. Here is the latest I have heard. Don't know if all or some of it has been posted. Sounds like a fu
104 Planefixer : "Emergency Power" - no such thing! "to clear a hill just prior to impact point" - there is no hill on the approach to LHR "the aircraft just had a sof
105 AirNZ : You say this information came from an NTSB official??? Where is he/she talking about then because there are certainly no hills remotely close to LHR?
106 AF1624 : If those are the words of the NTSB official... then we're in trouble. But I think "Emergency Power" means throttles pushed to their max forward posit
107 GOGOJET : " target=_blank>http://www.boeing.com/commercial/aer...s.pdf Yes, a good find and an informative brochure. Of note it says (fair use) "A review of th
108 Osiris30 : Just a point of order, and not meant to indicate whether or not I believe fuel freezing/waxing was an issue: Just because something has never happene
109 ULMFlyer : While I agree with you that because something never happened, it doesn't mean it can't or won't, your examples are not good illustrations of this arg
110 474218 : Since the accident occurred in the UK I would assume that the AAIB is the the lead agency in the investigation. The first thing you are told when you
111 Zeke : FMCs do "talk" to the engines...
112 Max777geek : Well I'm sorry I did, but I did read quite a bunch of post after mine stating the same doubts, so maybe it was my tone, which I apologize of, but not
113 JetMech : G'day Phil, I seem to remember that on Airbus' at least, that you can get the fuel densities in each tank from the fuel maintenance pages of the CMC
114 PhilSquares : Yes you can. But, that can be locked out in flight similar to what can be done on the Airbus. Plus, most companies don't really provide any instructi
115 JetMech : I see. With the Airbus (and perhaps Boeing as well), you can run many automatic tests via the CMC to help clear faults. I wonder if these functions a
116 PhilSquares : There are quite a few that are biased out in the air. And you're very correct about not sharing knowledge. But, I guess the big worry is people will
117 TristarSteve : On the B777 Boeing has split the CMC into two pieces. There are maintenance pages accessible through the CDU and then you use the mouse to navigate.
118 JetMech : I see. So there is no way to run any automatic tests from the CDU? That actually makes a lot of sense. Can you run automatic tests from the PMAT when
119 TristarSteve : Yes, I am nearly sure it does everything that the MAT does. I have never tried.
120 David L : Yes, there had been damage due to tyre bursts and the spray deflectors had been reinforced accordingly but the AF accident was quite different. A 2m
121 Post contains links Glbltrvlr : Latest update from Aviation Week http://www.aviationweek.com/aw/gener...0In%20777%20Crash%20&channel=comm:
122 Starlionblue : Say it was a couple of blobs of frozen fuel (or something in the fuel). Doesn't it seem a bit convenient that the engines both froze up at the same ti
123 Osiris30 : Yes, but the post I was referring to was actually similar in that it's a problem that *can* be foreseen, with a known outcome, that just hasn't manag
124 CX flyboy : Certainly in our operation, fuel freezing is less of a problem on the 777s than on the 744s and Airbuses. This is because the fuel is contained closer
125 Tdscanuck : All of the above is true, but fuel that's gone down the strut to the engine doesn't come back to the wing tanks. The only heat source in the wing tan
126 Litz : Didn't the AAIB report state that the autopilot commanded more thrust, and the engines initially responded, then fell back to slightly above idle, an
127 TristarSteve : Yes I agree that you have read it correctly. The throttle levers on a B777 are driven by the autothrottle motors, and nothing else, unlike the contro
128 Khobar : I never suggested it heats the wing tanks themselves. And its effects on fuel temperature are anything but negligible for where the heating actually
129 Yanqui67 : Did you read that? No, I am saying that this is within the engine. I am not going to argue with you. I am waiting for the reports from the AAIB. No a
130 Aaresl : Did I understood correctly that all commands to engines run only through throttle lever sensors? How are these sensors duplicated against failures? S
131 474218 : How about manually? Or you better leave the autothrottle engaged.
132 Nudlaug : Not wanting to read though the whole post and it makes no real difference anyway but following quote is not entirley correct, there are no fuel/oil he
133 Starglider : Except that with reducing volume of fuel in the tanks the influence of the tank heat exchangers, increasing the fuel temperature with small increment
134 Tdscanuck : All thrust commands run only through the thrust lever sensors (there are other commands that can go to the engine from other places). They are protec
135 Post contains images Starglider : Yes, that is what i meant. Starglider
136 Post contains links TUIflyer : 'Investigators examining the causes of the Boeing 777 that crashed on approach to Heathrow last week have determined that the aircraft had adequate fu
137 Tdscanuck : Well, given that AAIB disclosed this several days ago, it's not much of a surprise today. The part you posted also isn't accurate...the engines did r
138 Acabgd : FMC determines autothrottle limits, setting is determined by the crew.
139 Acabgd : Both correct - thrust levers would not revert to Idle as A/T was commanding more thrust. Levers move in accordance with commanded thrust, they do not
140 Tdscanuck : If the setting is determined by the crew, doesn't that make it not an auto throttle? I'm talking on the descent, not the N1 setting for takeoff. Tom.
141 Tangowhisky : On final approach, the autothrottle (if engaged in speed mode) is trying to the control the aircraft speed. The FMC thrust targets are not used durin
142 NAV20 : Early auto-throttles merely held a power setting made by the crew. Modern ones add or subtract power as required to maintain a set airspeed - but, aga
143 Post contains links and images JetMech : G'day Tom, I found some interesting pictures with regards to the FCOC and fuel heating. The following three photos show the fuel system arrangement f
144 Max777geek : The engines behavior doesn't let me think they failed to respond. If the thrust was not the commanded one, why didn't they shutoff or go below than f
145 TristarSteve : On the RB211-524G the fuel flow is as follows LP Fuel pump LP FCOC LP Fuel filter HP Fuel pump FMU Fuel Flow T/X HP FCOC HP Fuel filter On the Trent
146 Starlionblue : And you base this on? If you are looking a "trigger" event, a certain point in the descent could be it. So you think the engines were commanded by so
147 Max777geek : The engines themselves didn't look malfunctioning, from what Ive been reading. What did put them a bit above flight idle thrust, it's the mystery and
148 Starlionblue : Because as you descend temperature changes and the viscosity of the fuel changes.
149 Max777geek : I know, my tought was intended why didn't show earlier during descent. Assuming being more cold the fuel was more dense, it should have been more den
150 Merkuree : Somebody on this thread alluded to the video posted on youtube. For what it is worth, I reviewed the video at the time and posted the following back i
151 Max777geek : I guess from the video it is not easy to get if the approach went with that unusual AOA or it was some kind of desperate attempt to reach the airfiel
152 Post contains links and images NAV20 : That's consistent with what theAAIB says in its most recent update, Merkuree - that the engines initially responded, but then reduced thrust again:-
153 NAV20 : Max777geek, that's exactly consistent with the pilot trying to stretch the glide as long as he could. From an interview someone quoted, he was flying
154 DeC : Does anyone have the link for the YOUTUBE video mentioned above? Sorry if it's already posted but i can't seem to find it! thanks
155 NAV20 : I bookmarked a link to it, DeC, but it now says 'removed by user.' Either the guy has sold it, or it was a fake. In any case, all it showed was a few
156 Post contains images Starlionblue : Well, if some fuel was frozen, some part may have thawed and a cloth come loose. Totally unlikely of course. Except that the engines at the Habsheim
157 NAV20 : Starlionblue, coming in lower than planned was exactly what the Airbus Head of Safety Engineering said:- "Lauber said the pilots were supposed to fly
158 Post contains links Khobar : The Black Boxes from which the official report has been made show a series of anomalies, which has led a lot of critical people since 1988 to call in
159 Post contains links Starlionblue : We have clashed over that quote before. I know he said that but it has never made much sense to me standing alone like that. I'm not saying he doesn'
160 RJ777 : I know this is kind of irrelevant, but did the passengers ever get their belongings back?
161 MDorBust : No... just no.. Tyring to extend unpowered flight by essentially flying an extended flare is suicide. If the pilot really was trying to extend his gl
162 Tdscanuck : Nice pics! I agree with you that fuel heating system would be required to protect the engine bits from ice particles. In re-reading this part of the
163 MDorBust : Yes, a last minute movement to clear an obstacle does make sense. But, keeping the nose high through the approach does not. You keep the nose down to
164 Post contains images ZBBYLW : I think this is a possibility. In the event that you are about to hit a building right in front of you (but if the building was not there you could c
165 MDorBust : ..except there was no building... By all indications he was well above the structures in his flight path until very late in his approach. But let's d
166 Ikramerica : I keep hearing this argument against fuel contamination. But it's because they both happened within seconds (but not at the exact same time) of each
167 Khobar : So what happened to BA038 then, if video is sufficient evidence to figure out what went wrong? Based wholly on the idea that "footage of the crash is
168 NA : With more than 1000 posts on this topic I´m a bit lazy to go through, as only very few posts deal with this: Has G-YMMM officially been declared a w/
169 Moo : No two systems work 100% identically. Take two cars off the production line, one after the other, and fill both with 10ltr of fuel - drive them down
170 Post contains links Moo : Which was actually fairly significantly overblown, and resulted in Mattel issuing an apology to China - http://business.timesonline.co.uk/to.../consu
171 Post contains images Khobar : But if cars were designed and built to the same tolerances as aircraft...
172 Moo : But they are still built to tolerances, not identical. And when all is said and done, the tolerances aren't that precise either.
173 Sphealey : Respectfully I will have to disagree. I have sat in a chem lab with 19 other students dripping a compound into 2 liters of solution one drip at a tim
174 RedFlyer : But the fuel source at the point of origin was identical. What about the other companies that found lead contaminates in their products made in China
175 Moo : So let me get this right, you conducted a *controlled* experiment, in *controlled* conditions, with a particular outcome in mind, and hold that as su
176 Post contains images BA777ER236 : Discussions like this are all well and good, and yes, you are correct that if you increase the angle of attack above optimum, then the lift/drag rati
177 ZBBYLW : OK fair enough, I do not know LHR. OK I know this may sound uneducated, in a PISTON (i know of the difference) engine if you get carb ice, the engine
178 Spacecadet : Of course, as any pilot will tell you, that is what he or she is being paid for. Anyone can be trained to operate an airplane. What makes someone a p
179 Tangowhisky : Does anyone remember the Air Florida crash of the B737-222 In 1982? The aircraft did not have enough thrust power even though the pilots set the corre
180 MDorBust : As I said the first time I brought this up several versions of this thread ago.. I'm not bagging on the pilots. I'm just saying the most likely expla
181 Nudlaug : Fuel contamination...all i am saying is this ....... i have seen a B744 taxi onto the bay with 2 engines flamed out on landing, both fuel filters pull
182 Post contains images JetMech : Thanks for the info Steve! It makes sense that the fuel passes through the FCOC before the LP fuel filter. Perhaps the Trent 800 oil cooling system i
183 Starlionblue : I said "the footage", not "footage". I was specifically referring to the film of the AF 320 Mulhouse crash, which included sound and followed the air
184 Tdscanuck : Stuck fuel metering valve would do it. They can ice at ground idle, I'm not sure about flight idle. As power is applied it sheds anyway. Engines can
185 Zeke : Whilst not a tank heater, most aircraft have pumps installed in the tanks that use fuel for cooling, and on the 343 and I am fairly sure on other mod
186 JetMech : G'day Zeke, Thanks for the interesting info! I don't have too much heavy experience with the CFM-56, so the FCOM info is new to me. Certainly. All the
187 Aaresl : My common logic says that it is better to extend the glide to the limits and "drop from sky" at minimum speed/altitude. You just have to find right b
188 Post contains images NAV20 : MDorBust, please note that I didn't say 'holding the nose up' - I said, "..keeping the nose as high as he could to conserve height while maintaining
189 CX flyboy : I know that the fuel originated from the same fuel farm, but just to clarify, in normal operations of the 777, fuel is not transferred from tank to t
190 Rwessel : You almost never fly at min sink in a sailplane. When working a weak thermal, perhaps, and a few other rare occasions. Almost always you fly near you
191 Tangowhisky : If the span of time between the two engines behaving the same was 3 or more minutes, I would say it is more likely that it is a fuel contamination pr
192 Post contains links and images NAV20 : They were all 'smaller and slower' in my active days, Rwessel - cut my teeth on T21s and Slingsbys! Agree with you about 'safe' speed being comfortab
193 Tdscanuck : That sounds right to me. Airbus and Boeing have very different in-tank architectures. Airbii move fuel all over the place and have several more recir
194 Max777geek : Stated that they knew perfectly what they were doing, may be that they were so close and so low next to the airfield that heading down would have bee
195 Zeke : I think back in the 1980s a United 767 that had a couple of double engine flame outs, I think they both happened very close together. I think at the
196 MDorBust : That is 100% disputable. To find out for certain we would need to know the speed and altitude the aircraft was at when the event started, the remaing
197 Tdscanuck : I don't know about the specific incident, but copper contamination could do what you're suggesting. At temperture, copper will plate out in the HMU/F
198 Sphealey : Because if the engines had quit at 9000 then we would be discussing a different incident - either an off-airport crash or a successful glide landing.
199 Humbucker : Just some guesses after reading the interesting information on this thread: I'm guessing frozen fuel because the cause of the engine failure appears s
200 Dakota123 : Fact is, we don't know what the engines were doing in other phases of flight because no authority has offered that information (as far as I'm aware).
201 Tdscanuck : If it freezes at more than -40 degF it's not Jet-A by definition. Jet-A/A1 is a specification defined fuel. The freezing temperature does not depend
202 Post contains links TUIflyer : I hope the aircraft can be salvaged, although I know it is unlikely. Article below says it is unlikely, any ideas? BA 777 SPECIAL REPORT: http://letsf
203 Humbucker : It all depends on where the fuel is congealing. If the tank walls are the coldest contact points with the frigid -70 temperatures recorded during the
204 Tdscanuck : Jet fuel is a mixture of a whole bunch of hydrocarbons. By definition, the "freeze point" of the fuel is the temperature at which the *first* fractio
205 NAV20 : We know some of that, MDorBust. The reports so far say that the trouble began to become apparent at 600 feet and two miles out. The engines had just
206 SEPilot : My first flight instructor told me how to judge emergency landings: any one you walk away from is a beauty. From what we know at this point, this was
207 Humbucker : Thanks for that. Not having any real knowledge of the science I was speculating possible causes. If indeed precipitated and congealed Jet-A has the s
208 TristarSteve : Ba B777 operate in the USA with Jet A at -40deg, and in the rest of the world with Jet A1 at -47deg, and in this case China with Chinese fuel at -52d
209 Post contains links NAV20 : Jon Ostrower of Flightblogger presents a pretty comprehensive 'leak' from a US website:- http://www.flightglobal.com/blogs/flightblogger/ According to
210 JetMech : Yep, of course! I wasn't doubting Zeke's info one bit at all, just curious to learn more about something I haven't heard of or seen before. Would you
211 Max777geek : There is an alarm message on the Md80 telling the flaps are set to a position different from the lever setting. (flaps disagree).. You mean there is
212 Starlionblue : Changes in temperature and fuel levels occur at all times during the flight. In other words, you constantly have changing conditions that could trigg
213 Litz : Is there really a need for such a warning? It should be readily obvious if you push the throttle forward and the EPR doesn't change, that something i
214 Tangowhisky : Thanks NAV20 for picking up the Flightglobal blog. One thing that would narrow the investigation is if the fuel metering valve's position which is co
215 Post contains links Tdscanuck : I'm still mulling this over in my head. Weird things happen with solutions and I haven't totally convinced myself that you couldn't have a freeze poi
216 MDorBust : Actually, you just restated my opinion as to why the nose was up... and it had nothing to do with the pilots. Which is what I've been saying all alon
217 Khobar : The air temp may have been -70, but the aircraft skin temp would not have been that cold due to friction heating. The fuel loaded in China was not Je
218 474218 : There is no way the 777 could achieve a mach number high enough that friction heating would be induced on the airframe surfaces. Solar heating would
219 Humbucker : Somebody above said to add about 30 degrees for friction heating. So that would be around -40 degrees in the fuel. Whatever my layman's view is worth
220 Missourifarmer : This may sound like a stupid question(s) but could someone please clarify for me (just for my info): 1: does a "clean 767" mean "engines have power,
221 Osiris30 : Let's start with the easy part: 2) Yes... 1 foot of alt for every 12 feet travelled 1) No. Clean = Flaps @ 0, gear up, aircraft configured as it woul
222 Dakota123 : No, what I'm saying is that alarms/fault indication generally do not immediately annunciate on mismatch. Deadband and/or time delay is typically buil
223 Missourifarmer : Awesome!! Thanks!! That really seams simple now and makes perfect sense!!
224 Dakota123 : A very reasonable hypothesis, IMO. Not sure at all how aviation powerplant control logic is handled, but for stationary combustion turbines (at least
225 NAV20 : Hi, MissouriFarmer - taking sinkrate (the 'glide ratio') first, yes, 'one in twelve' means 'one down for twelve along.' For comparison, the most ordin
226 Dragon6172 : I am interested in the findings with the crossfeed valves. Especially the part where it says only one valve was found open. Can someone with knowledg
227 Tdscanuck : Stagnation temperature rise at M=0.8 is about 13% (in absolute temperature). It is absolutely a real factor to be considered. Tom.
228 474218 : At cruise that would be less than 8 degrees. -60 degrees X 0.13 = +7.8 degrees.
229 RJ777 : OK, we've got 8 threads here, plenty of speculation and opinions, but ARE THERE ANY NEW FACTS? You'd think at least info from the CVR or FDR would be
230 Post contains links Khobar : Inevitable to be sure - http://www.youtube.com/watch?v=e84nv6pZu9o&feature=related http://www.youtube.com/watch?v=nVMDkV5kJYk
231 Post contains links NAV20 : True, Khobar - probably the only thing that is certain about accidents these days! I find that that video purporting show BA38's final approach is bac
232 Starglider : In the B777 there are 2 crossfeed valves. A forward and aft crossfeed valve. The crossfeed valve switches directly control the crossfeed valves. Elec
233 Azhobo : On crossfeed systems that I have integrated in the past (not 777), we had two crossfeed valves. Ours were computered controlled, but activated by cre
234 Tdscanuck : No, it's a 52 deg F temperature rise. You need to use absolute temperature (Rankine or Kelvin), not C or F. At -60 degF at Mach 0.8, the stagnation t
235 Dragon6172 : Thats somewhat the way the system I dealt with worked. We had an intermediate position that moved the valve on the side you were going to feed from.
236 JetMech : Thanks for the link Tom, most interesting! I see how the system works now Zeke. I'm still a bit mystified to the above except from the FCOM however.
237 EK413 : With well over 200 posts on the BA 772 incident... Just wanted to know what is to happen to the remains of this bird... Written off / spares..? EK413
238 Max777geek : You would be right if it was just the speed not going up. In this case, as well it would be meaning something really wrong in everyone's car, it's no
239 David L : Considering that the crew first noticed that the auto-throttle had commanded more thrust and didn't get it, or at least didn't get it for long, I wou
240 Max777geek : I would assume that as well, but then I would wonder what all the posts indicating that "the engines responded as expected" were meaning, assuming th
241 NAV20 : As far as I know, Boeings have servos on the throttle levers, so the levers go forward as the A/T commands the extra thrust. No need for indicators o
242 David L : The official preliminary report does state that. It means the engines did initially give, or start to give, the commanded power but then fell back, f
243 Zeke : Nav, The N1 indications on the 777 are not that different from an Airbus, it has digital readouts and round dial/moving pointer indications. The N1 i
244 Starlionblue : As was mentioned before it's not like the levers have a huge range of movement. But the pilots would indeed see the movement.
245 Post contains links OyKIE : According to ATWonline it has been written off. http://www.atwonline.com/news/story.html?storyID=11608
246 NAV20 : Agree, Zeke - wasn't arguing that one system is necessarily better than another, just pointing out that they're different. Agree also that the power
247 Zeke : Got the impression you thought they did not have those indication on the 777 because the thrust levers move when throttle is active in some modes. Au
248 PhilSquares : I can't remember about the 757, but the 744 has autothrottles just like the 777. The work just fine in an autoland. ]
249 Post contains images NAV20 : Very possibly not, Zeke - I was quite young, and pretty 'open-mouthed,' at the time; and felt very privileged to be up front at all. Funny thing, we
250 David L : As I thought - cheers, Zeke. A display that shows commanded thrust and actual thrust all in one place seems extremely useful to me, not just a fall-b
251 Starglider : RAD ALT system has redundancy, 3 tranceivers (each with a transmit and receive anttenna), interfaced to several systems through ARINC 429 and the 2 A
252 PhilSquares : From the 744 QRH >SNGL SOURCE RA Condition: Both pilots’ displays referenced to the same radio altimeter receiver. Only get a EICAS message and the
253 AndrewUber : Having a hard time finding this - but can anyone confirm - has BA decided to save this frame or is it a write-off?
254 Tdscanuck : That's why the air/ground system has multiple inputs. On a 777, it has to see weight on wheels and truck tilt before it thinks its on the ground. Tom
255 Post contains links N328KF : I wanted to find out the same thing. Aviation Safety Network lists it as W/O, but I believe they're just guessing. http://aviation-safety.net/databas
256 Post contains links ANCFlyer : BA 777 Off Runway At LHR - Part 9 (by WILCO737 Feb 4 2008 in Civil Aviation)
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