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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

#311

Post by peteretep »

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.

I was very scared of flying for a long time. I fixed it by booking a flight a week for 12 weeks, starting the first week heavily medicated, and following the advice of a book on agoraphobia (Freedom from Anxious Energy). Then cut down the drugs progressively each week until it was none. Worked a charm

Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing

#312

Post by jsjohnst »

7952 wrote: post #255
gugagore wrote: post #191

Earlier quoted context omitted.

The cruising airspeed of an airplane is faster than its landing speed. I don't know if that alone is enough to rip the engine off the wing, but it's something that it sounds like you did not consider in making your point. [EDIT remove "roughly speaking an order of magnitude"]

It seems unlikely that a jet engine could rip itself off the wing in any scenario based on thrust alone. The forces involved are not that large.

Your wording makes it where you aren’t factually wrong, but a plane was in fact wripped apart due to the thrust reverser engaging on one engine of a 767:

https://en.m.wikipedia.org/wiki/Lauda_Air_Flight_004

Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing

#313

Post by justjico »

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.

Tons of good advice on this previous post: https://news.ycombinator.com/item?id=17654487

Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing

#314

Post by jsjohnst »

salawat wrote: post #273
gugagore wrote: post #191

Earlier quoted context omitted.

The cruising airspeed of an airplane is faster than its landing speed. I don't know if that alone is enough to rip the engine off the wing, but it's something that it sounds like you did not consider in making your point. [EDIT remove "roughly speaking an order of magnitude"]

The difference isn't that large in the grand scheme of things. The engine mount would have to be able to fail in it's operational envelope in order for the reverser kicking in to be realistic. In fact, the reversed kicking in would decrease the loading on the aircraft by decreasing it's airspeed. This isn't a case of acceleration being able to break the mount from the frame. If it ever could, one wouldn't want it on…

> but it isn't an instant catastrophic failure either.

Read the accident report and follow up on Lauda Air Flight 004. Boeing specifically was forced to issue a statement that it was virtually impossible to overcome a catastrophic failure outcome from a thrust reverser deploying at cruising speed.

Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing

#315

Post by sho »

t0mas88 wrote: post #142
cbhl wrote: post #139

The Boeing 787 is now about nine years old. I wonder how much of this is operator proficiency triggering latent bugs (aka, "pilots got too good at pushing buttons quickly"). The bugs in the Therac 25 were only discovered after the machine had been in production for a while (you had to be typing "too quickly" in order to get the software to trigger the bug with the safety interlock).

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.

I've seen a number of videos on youtube of reversers been opened, if not fully spooled up, off the ground. It's not common but it does happen, especially in high cross-wind or otherwise iffy landings.

Here's the first video I found but there are certainly others https://www.youtube.com/watch?v=-RO66a_nvus

Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing

#316

Post by jammygit »

peteretep wrote: post #311
alexbanks wrote: post #307

Earlier quoted context omitted.

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.

I was very scared of flying for a long time. I fixed it by booking a flight a week for 12 weeks, starting the first week heavily medicated, and following the advice of a book on agoraphobia (Freedom from Anxious Energy). Then cut down the drugs progressively each week until it was none. Worked a charm

Congrats on it working for you!

Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing

#317

Post by maxerickson »

exabrial wrote: post #12

Sort of off topic, but reverse thrust sort of boggles my mind. If you're sucking air in from the front of the aircraft and ejecting it out the front, don't those forces counterbalance each other?

Just draw arrows for how the air is moving the whole time.

The force on the plane is in the opposite direction.

Re: Boeing 787 Suffers Rare Dual Engine Failure on Landing

#319

Post by baybal2 »

weaksauce wrote: post #274
outworlder wrote: post #254

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 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…

I think there are a few options for a failsafe here. none where it would deploy the reverse thrusters and probably crash regardless of other inputs to the system(could be one or more of many inputs wheel speed, slats deployed, airspeed, elevation, throttle position, etc.) turning off the engine (presumably you want this because you are on the ground but your ground sensor is failing so you want to cut engine and appl…

Have a mechanical latches on reverse cowls that will be operated separately of the code that deploys reverse. Landing without reverse is better than falling like a brick.
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