I had expected this story was about a Rolls-Royce problem; their Trent 1000 engines are giving the 787 a bad name. But it looks like it was just a normal software interlock that would never cause a problem during flight.
Boeing 787 Suffers Rare Dual Engine Failure on Landing
221–230 of 365 posts
Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing
#222I think the auto shutdown of engines in flight, in case it senses reverse thrust, is a great design. The 787 is a replacement for my 767 (currently a pilot on the aircraft) and in 1991 a Lauda Air 767 suffered a failure in one of its thrust reverser and it became activated during cruise. The aircraft was destroyed in flight. The thrust reversers should not activate during flight (a air/ground sensors prevents that) b…
it's a great fail safe but not if you lose your engines in flight and can't relight them like in the article.
Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing
#223I think the auto shutdown of engines in flight, in case it senses reverse thrust, is a great design. The 787 is a replacement for my 767 (currently a pilot on the aircraft) and in 1991 a Lauda Air 767 suffered a failure in one of its thrust reverser and it became activated during cruise. The aircraft was destroyed in flight. The thrust reversers should not activate during flight (a air/ground sensors prevents that) b…
it's a great fail safe but not if you lose your engines in flight and can't relight them like in the article.
Cutting power to all engines in response to an event that is most likely to happen while the aircraft is operating close to, but not actually on, the ground is not failing safe.
Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing
#224Earlier quoted context omitted.
Switching off is much safer than a turbine overspeed past certain limits. Because an engine failure (one engine) is a situation all pilots are trained for and it has an almost certain safe outcome. Airplanes fly and land just fine on a single engine. We all train for engine failures all the time. On the other hand, a runaway engine fire or uncontained turbine failure is much much more likely to cause a crash. So almo…
But why not throttling instead of switching off then?
Overspeed protection takes place once everything else has failed. The engine controls have already attempted to throttle down and such. If that doesn't work then overspeed kicks in.
Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing
#225I think the auto shutdown of engines in flight, in case it senses reverse thrust, is a great design. The 787 is a replacement for my 767 (currently a pilot on the aircraft) and in 1991 a Lauda Air 767 suffered a failure in one of its thrust reverser and it became activated during cruise. The aircraft was destroyed in flight. The thrust reversers should not activate during flight (a air/ground sensors prevents that) b…
There is Airplane pilot on HN? I am surprised, did you make a career switch from IT?
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Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing
#226Earlier quoted context omitted.
It's not very typical for pilots to push buttons quickly. Especially not the thrustreversers and engine and flight controls. But it is entirely possible that nobody pulled the reversers while still airborne in 9 years, because it's a very strange thing to do. A bit like opening your car door while still driving 60 mph... Nobody does that in normal operation.
A bit like opening your car door while still driving 60 mph... Nobody does that in normal operation. You don't open and shut a door when you notice it didn't fully close because you can hear the wind?
Non-suicide doors[1] in cars are very difficult to open at 60 mph. Between air pressure, and poor leverage, you are going to have a hell of a time doing it.
Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing
#227Boeing’s answer seems to say if you accidentally pull the thrust reverser lever before the aircraft is on the ground it just force shuts down the engines. That sounds like an odd safety override. Surely a better solution would be to just not activate reverse thrust. Unlike car engines a jet engine can’t just be quickly restarted if it accidentally shuts down. It typically takes 30-60 seconds to get going. This and ea…
Do you have experience with aircraft engine design, or landing protocols, or insight in to the meetings when the engines were designed? If so, I'll take back my words but considering the manufacturer doesn't know exactly why this happened, and the engineers on the ground said it seems like a "software bug", it seems a bit presumptuous and frankly a bit comical to start saying things like: "Surely a better solution wo…
My answer to the question is no, but I am a pilot, and my expectation is an invalid input is recorded but is a no op. It is fly by wire so why not just no op the request? The idea such input suggest sabotage, is more paranoid than cautious. And shutting down the engines is hardly fail safe. It's just less fail danger than engaging the thrust reversers.
Quite a few turboprops have beta range that is supported for use in-flight. The purpose is to increase the rate of decent, similar to slipping the plane. So it's not always an invalid input; it's make/model/phase of flight specific.
Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing
#228Oh Dreamliner, still[0] making me look bad 12 years later. [0] https://news.ycombinator.com/item?id=9477941
I have never ever thought avionics software development would be in such a condition that you described in the link.
I am surprised to say the least.
I have always imagined avionics developers in a different way. Like having a thick rulebook to go through to add a new line to codebase etc.
Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing
#229Earlier quoted context omitted.
That's not a very useful reply. Can you explain where anonu is wrong? Can you explain why ? Can you give some evidence ? A bare dismissal is like five-year-olds arguing: "Did too!" "Did not!" It's not useful to advance the conversation, and it's not effective at persuading people.
It's quite possible that software creates new failure modes (as programmers I'm sure we all feel that to be true some days) while at the same time preventing more. When the software fails (if it did) we assume the software makes it more dangerous because we have a concrete example of what happened but not what could have happened in it's absence. This is what may eventually stall self driving cars for many years, the…
Statistically? I don't know.
But I have a friend who's an airline pilot. He was telling me about hitting windshear while coming in for a landing. The plane has software that not only tells him that he hit windshear, but also tells him what angle to put the nose at for best results. (The problem is airspeed. So you go to full power, but pitching the nose down also helps you gain airspeed. But the ground is down there, because you're coming in for landing. What angle is the best? The computer can figure it out and tell the pilot what to do.)
Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing
#230Earlier quoted context omitted.
it's a great fail safe but not if you lose your engines in flight and can't relight them like in the article.
Cutting power to all engines in response to an event that is most likely to happen while the aircraft is operating close to, but not actually on, the ground is not failing safe.
I am not sure there is a perfect solution here. you have competing issues that you need to resolve.
If it gets pulled in normal flight you would lose both engines but that's fine because you can glide and restart the engines. if the altitude sensor/ground sensor was broken and you want to override the reverse thrusters you have a conflicting goal there.
If you accidentally pull it during the approach you lose your engines and probably don't have time to relight before landing. in that case you might be able to still land by backup systems(FAU or just the ancillary tail turbine?) and glide?
I guess it boils down to how much trust you place in the pilots to not do the wrong thing or how much trust you place in the machine to not do the wrong thing/malfunction. It's a difficult question without a perfect solution imo.