Random Randomness.

[GalagaGuy]

A former 787 pilot on Reddit responded saying that the RAT had deployed which would indicate both engines failed or were shut down.   He also says the planes have systems that automatically set the flaps so it wouldn't even be possible to have a Flight 255 type pilot error event. 

[gehringer_2]

3 hours ago, GalagaGuy said:

A former 787 pilot on Reddit responded saying that the RAT had deployed which would indicate both engines failed or were shut down.   He also says the planes have systems that automatically set the flaps so it wouldn't even be possible to have a Flight 255 type pilot error event. 

Well if the plane has electric fuel pumps and all the power went down....

That would have to be some strange combination of events to do that though. The videos didn't show any obvious evidence of engine mechanical failure such as an oil or fuel plume, smoke, fire, or any other disturbance like turbine blade failure. It did just look like they throttled down.

If they had had enough lift to get to 650 feet, hard to figure how it was anything in the control surface configuration. That's probably above any remaining ground effect level so if the plane could lift that high it should have been able to at least keep flying level. 255 hardly got into the air at all. 

Edited yesterday at 04:39 AM by gehringer_2

[GalagaGuy]

9 hours ago, gehringer_2 said:

Well if the plane has electric fuel pumps and all the power went down....

That would have to be some strange combination of events to do that though. The videos didn't show any obvious evidence of engine mechanical failure such as an oil or fuel plume, smoke, fire, or any other disturbance like turbine blade failure. It did just look like they throttled down.

If they had had enough lift to get to 650 feet, hard to figure how it was anything in the control surface configuration. That's probably above any remaining ground effect level so if the plane could lift that high it should have been able to at least keep flying level. 255 hardly got into the air at all. 

My first thought was contaminated fuel but I can't imagine it would take out the engines that quickly unless it was literally water used to top off the tanks before the next flight.  

I just read online that they're focusing in on the a failure in the fuel system but I have no idea how that even happens to both engines at the same time as they run completely independent of each other.  

Edited 23 hours ago by GalagaGuy

[GalagaGuy]

Here's something interesting about the 787 I found online.  

https://www.availabilitydigest.com/public_articles/1006/787_power_loss.pdf

[gehringer_2]

40 minutes ago, GalagaGuy said:

Here's something interesting about the 787 I found online.  

https://www.availabilitydigest.com/public_articles/1006/787_power_loss.pdf

have to say this source would have better credibility if they knew the difference between pneumatic and hydraulic.

In any case, the article is dated 2015 and a fix was supposed to be rolled out that year. Now IIRC this airplane was possibly put in service before the date of the article and thus of the fix,  but if Air India sat on it for 10 yrs without doing the upgrade and then skipped their service intervals to boot, somebody there needs to take a fall.

[GalagaGuy]

6 minutes ago, gehringer_2 said:

have to say this source would have better credibility if they knew the difference between pneumatic and hydraulic.

In any case, the article is dated 2015 and a fix was supposed to be rolled out that year. Now IIRC this airplane was possibly put in service before the date of the article and thus of the fix,  but if Air India sat on it for 10 yrs without doing the upgrade and then skipped their service intervals to boot, somebody there needs to take a fall.

Yeah, I assumed that would have been long since patched and according to sources online, it has been.  I just found it interesting that there was a single point of failure when the entire point is to have redundant systems so that no one thing can bring down an aircraft.  

[gehringer_2]

18 minutes ago, GalagaGuy said:

Yeah, I assumed that would have been long since patched and according to sources online, it has been.  I just found it interesting that there was a single point of failure when the entire point is to have redundant systems so that no one thing can bring down an aircraft.  

It's pretty hard to design any complex system with total redundancy and at some point the law of decreasing returns will set in and the complexity will start driving reliability the other way. I'm not sure the 'single point of failure' paradigm is quite exactly applicable to software code itself as it is to mechanical systems. Code can have bugs, but once verified code can't fail or fatigue of suffer post manufacture defect etc., per se. You may utilitize redundancy in the machines running the code (Space shuttle was the a classic, 5 computers, took a 'vote' of 3 to proceed with an instruction). I suppose you could take the Space shuttle paradigm and actually be running 5 different code bases!  Machine control programming is an art of its own. As the number of input variables go up the number of possible corner cases explodes exponentially and in the real world, you can get highly non-linear and sometimes even inverse responses to your control outputs, and it all has to work in real time because lag introduces instabilities of its own.  I've done some very simple microcomputer control programming and all I can say is I wouldn't want to put my life in the hands of any of my code!