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Boeing 787 Suffers Rare Dual Engine Failure on Landing

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Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing

#301

Post by newnewpdro »

esemor wrote: post #189

I 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…

> In this case it seems that the 787 engines were reversed before the air/ground sensor had sensed ground and it is a potential problem.

What I don't understand is why does the reverse thrust input from the cockpit even influence the engine control when the air/ground sensor doesn't sense ground? It seems like an obvious lockout mechanism to have in place, if the result is shutting down the engines when the combination occurs.

Then just have a manual air/ground sensor override should that thing fail and you know you're on the ground and require reverse thrust.

Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing

#302

Post by heyjudy »

outworlder wrote: post #254
weaksauce wrote: post #222

Earlier 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.

> it's a great fail safe but not if you lose your engines in flight and can't relight them like in the article. It is still better to lose all engines than to have thruster reversers deploy in unsafe situations. You may stall without an engine at low altitude in a landing configuration, but you should still be able to glide for some time. Deploy reversers (or even a single reverser) and you fall like a brick very qui…

This existing system wouldn't likely cause loss of all engines unless the PIC commanded all engines TR in-flight. Also, it doesn't make sense that such a system would go out untested because such a system should try command engines to idle before cutting fuel to what it thinks are runaway engines. Finally, it's still unknown if it's a Boeing software issue or a RR T1K issue... the OP article is purely speculative and guesswork "news" is not how aircraft safety is handled.

Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing

#303

Post by 4thaccount »

monochromatic wrote: post #165
4thaccount wrote: post #119

Earlier quoted context omitted.

I found that I now distrust a lot of articles as people tend to get the things in my field blatantly wrong all the time. Things are complicated and rarely as simple as they seem. On the other hand, I've worked on things for hours before for someone to glance at the problem and solve it. Always a humbling experience.

https://en.wikipedia.org/wiki/Gell-Mann_amnesia_effect

I never knew there was a name for this, but I feel like everyone has come across this feeling at some point in their life.

Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing

#304

Post by zepearl »

esemor wrote: post #189

I 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…

Summarized, I understand that you mean that a malfunction in the "reverse-thrust-detector" (which switches off automatically the involved engine(s) when the reverse-thrust is not operating within its envelope => referenced as "feature" below) is more desirable than not to have it?

(because if, when having a mulfunction of the detector's "feature" in mid-air the engines switch off you still have some time to fix/override it, but on the other hand when not having it if your reverse-thrust engages you're screwed immediately - and even if the feature fails nearby the ground you're still be slow & low enough for at least some passengers to have some chance to survive)

Correct?

Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing

#305

Post by WalterBright »

bunderbunder wrote: post #223
weaksauce wrote: post #222

Earlier 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.

If the thrust reversers are deployed in flight, you're going to crash, even if near the ground. The airplane would be uncontrollable.

If the engines quit, you still have control.

Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing

#306

Post by ncmncm »

Does nobody remember the Lockheed aircraft that ran off the end of the runway because both the brakes and lift spoilers refused to deploy?

It was another case of misguided safety interlock. IIRC, they landed 20 knots fast because of storm conditions; the brakes wouldn't go with too little weight sensed, and the lift spoilers wouldn't go above a certain speed. Catch-22!

Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing

#307

Post by alexbanks »

esemor wrote: post #189

I 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…

I am very scared of flying (although I still do it, although it's not fun). Any advice/rationalism you can convey? I am a person that became sweaty and anxious reading your post.

Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing

#309

Post by tjohns »

alexbanks wrote: post #307
esemor wrote: post #189

I 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…

I am very scared of flying (although I still do it, although it's not fun). Any advice/rationalism you can convey? I am a person that became sweaty and anxious reading your post.

My advice is to look at the statistics. Commercial flying is much, much safer than any other mode of transport.

Do you get scared when you drive to work? Or take a train? Both are more risky. (Driving significantly so.)

More specifically... The pilots have extensive training, modern airliners have fail safes everywhere, and the amount of research and engineering spent on aviation safety is mind boggling.

See: http://airlines.org/dataset/safety-record-of-u-s-air-carrier...

Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing

#310

Post by sandworm101 »

esemor wrote: post #189

I 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…

Fyi, military pilot here, there are a handful of mil aircraft that can reverse thrust in flight. A great too for dropping down fast to avoid low/slow flight over hostile areas. There might be a relationship between that ability and this problem.
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