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Swift 737-400 crash on final to Vilnius (Lithuania)
Gabriel has explained that, unless a slat actuator has a locking mechanism (which would include a valve to lock in the hydraulic fluid), slats will retract against strong air (or terrain) loads upon a loss of hydraulic pressure. This is precisely what did occur on AA191. I posted the explanation from the final report to confirm this. I suppose that is also a complete waste of your time.
All I'm saying is that, until we know the design of the 737-400 slat actuators, nothing can be derived from a photo of a retracted actuator, and even then, impact forces are entirely unknown variable.
But apparently, being proved wrong and learning a thing or two is a complete waste of your time. So be it.
737 does have retention valves, or whatever they are called.
(This guy must be the most knowledgeable human about 737s that ever lived on Earth)
--- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
--- Defend what you say with arguments, not by imposing your credentials ---
(This guy must be the most knowledgeable human about 737s that ever lived on Earth)
Nice find! I don't have 1:45 to go through that right now but I scanned through it. Are you referring to the slide about LE Uncommanded Motion? There is a description of a hydraulic lock there but it is triggered if the LE's move out of position by the FSEU. The 737-400 doesn't have an LSEU, so I doubt it has this particular locking feature. Also, the fact that this locking feature is only triggered by an uncommanded LE movement makes me think there is no other locking function under normal operation.
Or if that's not the right part of the video, send me the time on the video that you are referring to.
Nice find! I don't have 1:45 to go through that right now but I scanned through it. Are you referring to the slide about LE Uncommanded Motion? There is a description of a hydraulic lock there but it is triggered if the LE's move out of position by the FSEU. The 737-400 doesn't have an LSEU, so I doubt it has this particular locking feature. Also, the fact that this locking feature is only triggered by an uncommanded LE movement makes me think there is no other locking function under normal operation.
Or if that's not the right part of the video, send me the time on the video that you are referring to.
The feature is explained in the first minutes of the video (check 4:14) when he is talking about the inboard LE Kruger flaps. He mentions there that the slat actuators have the same feature.
--- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
--- Defend what you say with arguments, not by imposing your credentials ---
By the way he is the guy that owns the "The Boeing 737 Technical Site", which he has had for a couple of decades now and is constantly updating, and he started to do YouTube videos a couple of years ago that he also posts in the relevant sections of his website, that's where I found this video:
He is the guy that made those 737-900 plug doors videos too after the Alaska incident. And I also exchanged a couple of emails with him and he is very humble and open.
--- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
--- Defend what you say with arguments, not by imposing your credentials ---
The feature is explained in the first minutes of the video (check 4:14) when he is talking about the inboard LE Kruger flaps. He mentions there that the slat actuators have the same feature.
Thanks, I found it. He isn't specific there about which generation, but maybe that means it is present from the original design. And, of course, the real question is: would a hydraulic lock stand up to impact forces? It certainly wasn't designed to...
Thanks, I found it. He isn't specific there about which generation, but maybe that means it is present from the original design. And, of course, the real question is: would a hydraulic lock stand up to impact forces? It certainly wasn't designed to...
Once you roll almost inverted and dig the wing into the ground, all bets are off, as they should because at that point you don't need that slat anymore anyway.
--- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
--- Defend what you say with arguments, not by imposing your credentials ---
Also, the fact that this locking feature is only triggered by an uncommanded LE movement makes me think there is no other locking function under normal operation.
Do you actually read the nonsense you write before posting it?
737 does have retention valves, or whatever they are called.
That's a standard feature for most, if not all jets. That's why I wrote that I never heard or experienced such an uncommanded slat retraction case in decades.
Imagine that you are on approach, fully configured, you are experiencing a loss of hydraulic pressure and the slats suddenly retract?
Such a design would never ever be certified.
If such a failure would be even remotely possible I'm sure that every sim instructor would love to throw this error at you.
Such a design would never ever be certified.
If such a failure would be even remotely possible I'm sure that every sim instructor would love to throw this error at you.
You keep making these false, absolute statements using the word ‘never’. The DC-10 was indeed certified that way. And yet, you persist in denying this.
By providing hydraulic redundancies and a demonstrated controllability with a slat asymmetry condition, the DC-10 was certified as designed.
it was not certified to fly with one entire engine pod ripped off and flung over the top of the
wing. I guess regulators missed that one…
So that actually happened. Do sim instructors love to throw that one at you?
Sigh, you apparently don't understand what 'catastrophic damage' means. Every slat equipped plane can fly with a slat asymmetry.
Simulating catastrophic damage in a sim makes absolutely zero sense.
I am quite sure that what I did see in the video corresponds, with almost certainty, to parts of the wing separating from the 737.
Well, then you are disagreeing with our opinion regarding a video that you didn't even watch.
What video and time please?
I don't know what this video has to do with the fact than an uncommanded slat retraction is impossible without catastrophic damage and that's the only thing I'm stating over and over again.
What video and time please?
... slat retraction is impossible without catastrophic damage ...
Any of the videos. The fireball part. Which pretty much indicates catastrophic damage..
--- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
--- Defend what you say with arguments, not by imposing your credentials ---
Who, other than you, is talking about an uncommanded slat retraction in flight in this accident?
--- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
--- Defend what you say with arguments, not by imposing your credentials ---
Well, speculating about the aircraft state at or after the impact doesn't make sense if you want to find out why the crash happened and/or why the 737 started to roll.
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