Posted on 01/18/2008 11:12:07 AM PST by saganite
LONDON - The engines on a British Airways plane that crash-landed at London's Heathrow airport failed to respond for a demand to increase thrust, a preliminary accident report said Friday.
Using flight recorder information, investigators will focus on what other systems might have caused the engine failure, according to the report from Britain's Air Accidents Investigation Branch.
The British Airways Boeing 777 made a crunching touchdown short of the runway on Thursday, ripping off the plane's landing gear and severely damaging the two engines and wings. Nineteen injuries were reported among the 152 people aboard.
"The aircraft speed reduced and the aircraft descended onto the grass short of the paved runway surface," the report said.
The crumpled aircraft remained at the end of one of Heathrow's two runways Friday.
British Airways said it expected to operate all of its long-haul flights from Heathrow on Friday and 90 percent of short-haul operations.
Report doesn’t say it, but this airplane had Rolls Royce Trent engines.
There’s more to it than the engines. Everything on modern planes is controlled by computers. It may not be the engines at fault but instead something in the software.
But how did it lose power so suddenly? Surely something as complex as an airplane might be expected to have battery back-ups and turbine generators, for situations where the engines fail.
Yes, they do. It could be a lot of things and should not, by design of the aircraft, have been any of them. I can think of a few that could have caused it but should not have. We will just have to wait and see what the investigation turns up.
You’re talking about electric power and planes do have backups for that but if both engines fail to resond there’s nothing you can do but go down. There is no backup for total loss of engine power.
That article phrases it differently than I’ve seen before. “Failed to respond for a demand to increase thrust” is not the same as “lost power.” The engines on a 777 are controlled electronically; moving the throttle levers in the cockpit sends signals to a computer that does all the actual work in terms of increasing fuel flow to the engines. If that FADEC system failed somehow, and the pilot pushed the throttles forward and nothing happened, that might explain why some early witnesses said that the engines were still running.
}:-)4
They mean they lost engine power, not electrical power. For some reason, which they will eventually discover, the engines did not respond to demands to increase thrust on approach. Think of it as pressing on the gas peddle of your car, and nothing happens.
“...failed to respond for a demand to increase thrust...”
Looks to me like there would be options open to failure. I imagine at landing there is so much going on that there are numerous possibilities. I’m completly ignorant on this - but I wonder if the flaps are in a certain position that limits the amount of thrust that the computers will allow to the engines or something? I seem to recall some show on planes where the pilot (maybe a fighter plane??) was saying - you CAN’T stall the plane, even if you wanted to - it won’t let you.
That’s an interesting comment you made and on target. If the FADEC completely fails the engines (on the plane I fly) will auto shutdown. That’s saying a lot though. The FADEC usually fails to a degraded status where the engines will continue to operate without overboost protection. Total failure of all FADEC control simultaneously is unheard of as far as I know.
It becomes serious when your car is several hundred feet above the ground or you are trying to beat a train to the crossing.
“...failed to respond for a demand to increase thrust...”
I have nightmares like this where I push on the brake in the truck and nothing happens! I can’t imagine the panic in real life. Kudos to these pilots for getting the plane down safely (all in all).
My Brother flys a 777 for Delta......he thought it was curious that the plane did not catch fire. Could the pilot have run out of fuel?
Lack of fuel would certainly cause a loss of response! That’s something easily checked though and if that were the case I think we would already be hearing about it.
Especially since this particular plane had probably done at least hundreds of landings on its present flight software version. (One place to look, btw ... did Boeing or somebody recently install an upgrade to this plane?)
Unless there was something very strange about the configuration of the aircraft -- various mechanical or some sort of electrical failures, say -- it's difficult to see how the software would suddenly refuse to honor the throttle requests.
My guess is that they were low on gas...
Maybe. In that case, you would’ve had to have a failure in the fuel gauges. Like everything else on the 777, the amount of fuel left is shown electronically on screens.
There was one example I can think of, many years ago in Canada...an Air Canada 767 was flying with the fuel gauges inoperative. They used dipsticks to measure the fuel in each of the three tanks, but when they converted the readings to the amount of fuel needed, the mechanics hosed up the conversions (the 767-200 was AC’s first all-metric airplane) and loaded half the fuel it needed. It ran out of gas and ended up making an amazing power-off landing on an old abandoned military airstrip that had been turned into a dragstrip. Ever afterward, that airplane was known as the “Gimli Glider.”
}:-)4
My guess is that they were low on gas...
That was my first impression but I think we would be hearing something to that effect by now. I could be wrong and they may be sitting on the info. Also, you would think the crew would have been aware of it and declared a fuel emergency. I’m starting to think it was something else.
There’s a short video snippet out on Youtube that’s supposedly of this airplane on short final as it crossed over a highway. It didn’t look low, but it was VERY nose high compared to the 777s I’ve seen land. I wonder if the pilot was already down on power and he was dragging it in trying to make the airport.
}:-)4
Hmm, interesting, although I remember reading yesterday that the plane also had a complete power outage.
BSOD ?
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