777 Heathrow crash - Page 2

Normy · 04:45 PM

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!

rick-l · 01-21-2008, 05:19 PM

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?

Jeff Higgins · 01-21-2008, 05:42 PM

Quote:

Originally Posted by Normy

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!

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...

javadog · 01-21-2008, 05:50 PM

Quote:

Originally Posted by Jeff Higgins

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

rouxroux · 01-21-2008, 06:01 PM

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)?

Jeff Higgins · 01-21-2008, 06:55 PM

Quote:

Originally Posted by javadog

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

Sure thought I did...

JR

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...

stealthn · 01-21-2008, 08:05 PM

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

edgemar · 01-21-2008, 08:52 PM

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?

beepbeep · 01-22-2008, 03:03 AM

Quote:

Originally Posted by rick-l

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?

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.

beepbeep · 01-22-2008, 03:07 AM

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.

onewhippedpuppy · 01-22-2008, 04:27 AM

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?

beepbeep · 04:44 AM

Quote:

Originally Posted by onewhippedpuppy

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.

supdaf · 01-22-2008, 05:17 AM

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.

Joeaksa · 01-22-2008, 08:01 AM

Quote:

Originally Posted by Jeff Higgins

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...

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.)

tcar · 01-22-2008, 10:01 AM

Quote:

Originally Posted by Normy

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.

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