Posts by user "OldnGrounded" [Posts: 45 Total up-votes: 95 Pages: 3]

AA191. The NTSB report with probable cause was published within less than a year, IIRC. But it wasn't all that difficult to determine once they knew that forklifts were being used to R&R engines. In the 737 rudder hardovers, I think eight years passed between the first crash and a probable cause finding (in the second crash) that implicated the PCU servo. Of course, as someone has already posted, much more monitoring, data recording and transmission is available now in 21st century aircraft, although the accident aircraft in this case may not have transmitted much in the time available.

As an expert on human memory and cognition has pointed out above (and we all more or less know), what that survivor remembers or he thinks he remembers \x97 and what we think or are told he doesn't remember \x97 cannot be considered accurate or reliable. At all.

They are electrically operated, and there have been known issues and incidents. See, e.g., LATAM 800. Edit: Just an old engineer, but the chances that uncommanded seat movement was causative in the AI crash seem vanishingly small.

https://en.wikipedia.org/wiki/LATAM_Airlines_Flight_800

tdracer has let us know that TCMA relies on inputs from three radio altimeters and two WoW switches and that at least one from each set must report on-ground.

With both engines?

Ah, yes. Missed that. Thanks. But I have to assume (I know) that any responsible aviation engineers designing a system that can shut down both (all) engines simultaneously when the airplane is on the ground is going to want to make very sure that the airplane is on the ground.

But I'll check.

I've been looking and haven't found the current TCMA configuration for that engine yet. Perhaps of interest, I did find that Boeing petitioned for and received an exemption from \xa7\xa7 25.901(c) and 25.1309(b) in 2016.

Petition:
https://downloads.regulations.gov/FA...tachment_1.pdf
Grant of exemption:
https://downloads.regulations.gov/FA...tachment_1.pdf

I'll keep looking to find out what they actually did.

Thanks for posting this. I read it quickly and glanced at the drawings, which are adequate for the patent application but not nearly adequate to understand the system in any depth.

I note that, unless I missed it, the patent application doesn't address a mechanism for determining whether an aircraft is actually on the ground. I suppose that will depend on some of those "several other digital inputs."

. Emphasis added.

I'm still looking for identification of the relevant inputs for TCMA on the GEnx-1B. If anyone has suggestions, please share.

Right. When the aircraft is on the ground. What inputs are used to determine whether the aircraft is on the ground?

Thanks for the heads up. The story also says, "No cause has yet been identified for what would be an extremely rare power loss from both engines, but on Sunday the Indian civil air authority (DGCA) began urgent pre-flight inspections of fuel systems, electronic engine controls and other systems on Indian Boeing 787s."

And it quotes Juan Browne (Blancolirio): \x93There was something terribly wrong with this 787 jet and we need to find out really quickly what went wrong because we\x92ve got a thousand of these operating today and operators need to find out what happened.\x94

Folks, if an interim report or other official communication from the investigation is released, it will almost certainly come from India's AAIB or at least be posted to its site. So checking there before posting something like that here would be a really good idea.

https://aaib.gov.in/

Admin note: the url is correct, app are the Government allow advertising on their sites!

SPlot

Please, we really don't need any more snark in this thread. And your snark suggests that you may not understand the implications of the story cited in the posts you quoted.

That the Times reports, clearly based on information from official Indian sources, that loss of thrust in both engines was a key factor in this crash, and that DGCA has ordered urgent inspections of 787s because of preliminary findings of the investigation, is important news from one of the most responsible newspapers anywhere. And Juan Browne's urging quick action and citing the importance to the entire fleet and to aviation generally is also significant. He's a respected aviator many here pay serious attention to.

Yes, so do I. But we live now in a world where information from officials who aren't quoted because they aren't authorized to speak, or are authorized but insist on anonymity, is very often the only information available, especially early in an investigation like this one. The fact that this story is in the Times gives me a fair amount of confidence that what is being reported really is from official sources. They actually have journalistic standards there.

Folks, if an interim report or other official communication from the investigation is released, it will almost certainly come from India's AAIB or at least be posted to its site. So checking there before posting something like that here would be a really good idea.

https://aaib.gov.in/

Admin note: the url is correct, app are the Government allow advertising on their sites!

SPlot

Unless I've missed another one, the relevant petition was for a time limited exemption for TCMA for the GEnx-1B. It was granted. See attached . Nope. Uploads failing. See here:

https://downloads.regulations.gov/FA...tachment_1.pdf

https://downloads.regulations.gov/FA...tachment_1.pdf

I haven't yet been successful in finding the details of the solution that would have brought TCMA for that engine into compliance by the 2018 deadline requested and granted.

It seems pretty unlikely that a bird strike that took out both of those very big engines simultaneously would not have been fairly obvious in ways that nearby observers (e.g., the crew, ATC, airport personnel?) would have noticed. Possible, of course, but I don't think we've seen any evidence that points in that direction. Also, for what it's worth, the Times of London June 15 story " New clues point to engine failure for cause of Air India plane crash " cited here in the closed thread includes this:

A poster in the closed thread pointed out, properly I think, that the Times shouldn't be relied upon for presentation or interpretation of technical information. Like most general news organizations, their reporters and editors (mostly) just don't have the background to assess, filter and explain complex processes and technology. Unlike many, though, the Times can generally be relied upon to seek appropriate sources and report accurately what those sources say. I think it's very likely that Indian authorities have ruled out a bird strike, and I also think those authorities are competent to make that decision.

And a sensor per channel per engine for actual thrust, and sensor inputs in addition to WoW switches to validate on-ground state (perhaps radio altimeters, as described by tdracer for some of the 74s, which I misread as 787s). I, too would be surprised \x97 stunned \x97 if all of that had been implemented. I really want to know what exactly was implemented, and when and in which specific airplanes/engines. What I expect, though, is that when we learn all of that, we'll decide that it really is exceedingly unlikely that TCMA shut down those engines in Ahmedabad the other day. But it sure looks like something did.

Thanks. Do we know that these are monitored by TCMA for air/ground state and if so, do we know the logic used to make a determination based on those inputs? Alternatively, do you know where we should be looking for those answers?

Thanks again. Yes, I checked the MMEL too. It also says that the aircraft may be dispatched with one of two TCMA functions operational . Edit: dragon6172 has pointed out that the cited MMEL entry for TCMA applies to Rolls Royce engines, so not relevant here.

Ah, you're right. Didn't notice. And the accident aircraft did have GE engines. Thanks.