777 Heathrow crash
 

Anyone want to guess what happened here?

777 Heathrow crash

Reports of failure to respond to autothrottle with plenty of fuel????

Gremlins?
http://upload.wikimedia.org/wikipedi...ling_hare2.jpg

Good discussion of this on Slashdot:
http://it.slashdot.org/it/08/01/20/1430224.shtml

FWIW.

Best,

Kurt

edit: Possible causes: 1) software failure; 2) fuel delivery system; 3) fuel (refueled in China); 4) human error; 5) ???? Apparently both engines failed to respond to computer and human input.

That's some pretty good piloting.

Well they have all FDR's and CVR's, we'll find soon enough. Sounds weird if both FADEC's would quit at same time. Fuel problem would usually make engines flame out, but not at same time. As far as I understood, these two kept milling but didn't want to spool up?

I bet on the software problem (probably something high up in the chain). FBW is trippled and running on embedded systems...unlikely?

What happends with ETOPS if they find FBW guilty?

I am tipping fuel. Ran out of.

What this, "it refuelled in China". Whats the significance of that?

Fuel leaked out when it crashed, according to first rapports. Fortunately, main gears didn't puncture the tanks so no fire. Also, engines feed trought different pumps and ofte, different tanks. They don't "stop respondin" simultaniously but flame out independently accompanied by lot's of warning bells and lights.

Same with contaminated fuel...unlikely that they would both just quit or stop responding at the same time if fuel was bad.

No bird impacts on engines either...maybe water in fuel freezed in feed pipes prior to feed transfered to central tank and it just coincided with landning?

Or freek "throttle lever sender sensor snapped" thing?

http://www.aaib.dft.gov.uk/latest_news/accident__heathrow_17_january_2008___initial_repor t.cfm

" A significant amount of fuel leaked from the aircraft but there was no fire." ...
"Initial indications from the interviews and Flight Recorder analyses show the flight and approach to have progressed normally until the aircraft was established on late finals for Runway 27L. At approximately 600 ft and 2 miles from touch down, the Autothrottle demanded an increase in thrust from the two engines but the engines did not respond. Following further demands for increased thrust from the Autothrottle, and subsequently the flight crew moving the throttle levers, the engines similarly failed to respond. The aircraft speed reduced and the aircraft descended onto the grass short of the paved runway surface.

The investigation is now focussed on more detailed analysis of the Flight Recorder information, collecting further recorded information from various system modules and examining the range of aircraft systems that could influence engine operation."

P.S. Do BA 777 fly polar route between LHR and Bejing? Middle of winter + polar route + water in fuel + fuel transfer =? Sound unlikely though, aren't engine feed tanks on the B777 outboard of the engines?

I still bet on SW/Autoland/FBW problem...

Problem for 777 ETOPS cert?

Top notch flying. Sounds as if they nailed the centerline, if not the runway.

We'll be sending a survey team over shortly, I'm sure. We are all assuming it will be to confirm it is a write-off for the insurance company. Then again, no one has written off a 777 yet, and no one wants to be the first. BA may be willing to spend up to the cost of new to fix this one. There are no open slots in the firing order for a few years, and they really need that airplane. Looking at that quartering left rear photo, though, with the walking beam torn loose and sticking out like that - I think she's done. I'll be in Cardiff in a couple of weeks on a 767 SIP tech assist for BA; I'm sure we will be talking about it then...

Jeff,

Great info. Any insights on the 787 delays, barrel mismatches, fasteners etc? I read on another blog that people working the line are advocating using airframe #1 for destructive testing instead of another one down the line since #1 is proving so troublesome.

For an idea of the complexity and the redundancy of the fuel system in the big planes, here is a basic diagram of a 737 fuel system. I don't think any single clogged line could cause the problem, and doubt fuel ice was an issue. Each tank has 2 feed pumps, and you can fuel either engine from any tank.

I would think it was a software problem, since neither engine responded.

http://www.b737.org.uk/schemefuel.gif

dude, fill in some some acronyms

• FDR's, -- Flight Data Recorder
• CVR's, -- Cockpit Voice Recorder
• FADEC's -- Full Authority Digital Engine Control ??
• FBW -- ???
• ETOPS -- Engines Turn Or Passengers Swim??

ETOPS Engines Turning Or Passengers Swim! :D :D :D
FDR
CVR
FADEC
FBW

There are a lot of other 'nicknames' for this one, but it really does mean FlyByWire.

Most of the nicknames start with 'fing' or 'French'

i'm sure opinions will vary widely on this subject, but when i flew professionally many of us were fond of saying 'friends don't let friends fly by wire..' :D

i'd hate to think i was screwed by a bad cb or 'bad wire'..i'd rather be the 'hero story' of the pilot who lost all hydraulic flight control assist and had to 'muscle' the plane down.. ;)

Nothing I can share here. And remember, anything you might be reading on any blog is no better than unsubstantiated rumor, based on second or third hand information at best. Everybody knows somebody who has a cousin whose brother-in-law works on... fill in the blank. Or my personal favorites, the "unamed sources" or "speaking on the condition of anomymity..." No more than internet busy-bodies; the modern equivelent of a bunch of cackling old hens.

bock-bock-bock

I'm gonna guess FADEC (Engine/fuel computer) or Auto-Throttle inputs. I think something (or someone) "told" the engines to shut off. By "told" I mean either by failure of a computer (which with redundancy is hard to believe with both engines at once) or an input commanded a spooldown. One thing for sure is pilots around the world are very interested in what happened, probably as much as Boeing is.

I get this from a woman that flies A320's for United Airlines...

The world's airlines are in a BIG QUANDRY right now. The 777 is in the process of losing it's ETOPS certification. That means that it CANNOT fly the typical routes over the Atlantic or the Pacific that it has been flying.

The long and short: The 777 autothrottle system DID NOT respond when the pilots applied full thrust. The autopilot system tried to increase thrust, and the thrust levers moved forward, but [B]nothing happened![B] It appears that this is the [B]first instance of the failure of the fly-by wire system.[B]

The Airbus 320 pioneered the system where the flight controls were controlled not by wires and hydraulic motors, such as the power steering on our Porsches, but by actual electric servos, kind of like a model airplane. And one of the first A320's flew into trees at an airshow in Basle, Switzerland in 1988 as a result of that stupid system.

All modern Airbuses are operated by "fly by wire" Including the new A380, which can carry 500+passengers. Stretched versions, if built, will cary 800 people.

So we are all familiar with the debate about large airplanes with fly by wire. So what? they will save a lot of money....

But what happens when an airplane carrying 800 people crashes? We just watched a fly-by-wire attempt to kill a bunch of persons....!

N!

Anyone on the list know how the flight controls work in a 777?

• Are the controls to the engines triple redundant?
• Do the commands go there on a serial bus(s)?
• Would a production plane have enough instrumentation to know where in the chain the "more power" command was dropped?

Where do you get this bull*****? The investigation has barely started, and already uninformed ass hats that desperately want to appear experts "know" what happened... amazing...

Did I not read "I get this from a woman that flies A320's for United Airlines..."

Sure thought I did...

JR

So, just for fun, what happens next month when someone is supposed to fly UAL from ORD to LHR on a 777? (besides the obvious requisite prayer)?

So did I; so what? "...a woman that flies A320's for UAL..." knows exactly what happened on a BA 777 before the investigation has even really begun?? Uh huh...:rolleyes:

The new Microsoft Sync in the cockpit must have blue screened taking down all the other windows systems :D

Is everything computer controlled? or is there a direct electrical link to the servos that control the engines electrically and bypass the computers in an emergency?

Found on airliners.net:

EEC- Electronic Engine Control, it is mounted on the engine and its the brain of the engine. Each engine has one. It is a computer that is used to do all the functions for the engine. it receives data from all the engine components and uses the data to make the engine operate at its optimum settings. It has two channels A and B. Every time the start switch is actuated the EEC channel changes. Only one channel is in control at a time. The EEC is always ready to take over in case of failure with the other channel. The other channel is monitoring the active channel to make sure they are both receiving the same data. The EEC operates on the ARINC 429 avionics data bus. The EEC is powered by the aircraft once the start switch is actuated or the EEC maintenance switch is on. Once the engine reaches a certain N1 or EPR setting then the EEC alternator powers the EEC. Meaning the engine itself is self powered by the alternator that is spinning.

FADEC-Full Authority Digital Engine Control, This is what is called when an engine is Fly By Wire. That is, no mechanical controls. The EEC controls all engine operations. The goal of FADEC is to operate the engine at its highest efficiency in all flight aspects.

AIMS- Aircraft Information Management System- On the 777 this is the brain of the aircraft. All data is brought in and through the AIMS system. There are two AIMS cabinets left and right. They are essentially the EEC of the 777 aircraft. The AIMS system makes the 777 what it is. It eliminates many avionics black boxes because the AIMS does those functions. As an example the Autothrottle computer which is found on most airliners is eliminated on the 777. The function of A/T is a function of AIMS. Other functions include, Primary Flight Displays, Flight Data Recorder System, Aicraft Conditioning System and other functions. The AIMS system receives and transmits data on four 629 buses. I could go on and on with AIMS. It is very complex and I just gave a quick description of it.

EIDU- Engine Data Interface Unit- On the 777 there are two. One each for each engine. This box is what lets the AIMS system interface with the EEC. The EECs are on the 429 bus while the AIMS is on the 629 bus. In order for the system to communicate with each other the EDIU takes care of it. It converts the data coming from the EEC to a 629 signal for AIMS to use and vice versa convert 629 to a 429 signal for the EEC to use. This is the sole way for the flight deck to make the engine do what you want it to do. You bump the throttle up and the signal is sent to the AIMS which in turn sends it to the EDIU and then to the EEC which tells the engine to add some gas. The feedback is then sent back the same way it came. The EDIUs are three channel A, B, and C.

Snip #2:

From the engines' point of view, there is only one command...the thrust lever position. The autothrottle moves the thrust levers via servo, the flight crew does it via their arm, but the same chain happens. Thrust lever moves and updates resolver position, which commands AIMS, which commands EDIU, which commands EEC, which commands fuel/stator/etc.

Goran, correct me if I'm wrong, but don't some FADEC engines still have a physical connection to the throttle? The autothrottles are still manipulated via servo, but there is an actual connection between the engine and throttle controls that is manipulated by FADEC?

Don't know about other but this particular 777 was equipped with Rollers and there should be no "throttle cable" between throttle and engine. Throttle inputs travel trough ARINC 429 bus between the cockpit and the spinning part.

Cue: Most BA 777's are equipped with GE engines, I read somewhere that this was the only one with Rollers.


All this is of course pure speculation from my side.

I think it is important to note that the three major engine manufacturers (GE,Pratt,Rolls) have all had fly-by-wire engine controls for many years before the 777. As far as I can recall, and I work on these things, this has not happened before so this could be particularly problematic. However the 777's systems are very different from previous Boeing aircraft and this could be the issue. How different are the engine controls? I suspect similiar design convention but the 777 is a good bit different. They flew a good distance (I don't recall where this airplane departed from) the engines and autothrottle worked perfectly and they only have a problem on final. Odd. Maybe there were some problems with the engine/autothrottle system but I have not heard of any at this point. It will be interesting.

Knowing a few of the female pilots with United, I would much more trust her opinions about how to bake a cake than how the ATS system works on ANY airplane.

Lets settle down with the ideas about how this happened and why until the investigation is completed.

Joe A
(Ex-Factory pilot for Boeing, McDonnell Douglas and Bombardier for many years.)

Why is the 777 losing it's ETOPS certification? Because of this?

>I get this from a woman that flies A320's for United Airlines...

Is she hot?

Because some woman that flies A320's for UAL told him it is.



Party pooper.;)

I believe crash happened beacuse somebody pulled the runway under the aircraft just as they were about to land...

My sister's best friend's aunt saw on the Internet that UFOs were spotted at the airport just before the accident.

Just sayin.