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Alaska SNA [MLG Failure]


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Alaska SNA [MLG Failure]

Old 09-16-2023, 01:12 PM
  #81  
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Originally Posted by Spif
Where were you earlier in the thread when plenty were talking about a hard landing and ****ty young pilots? That was conjecture.
It makes no difference where I was. I choose to comment when and where i will, with my own words because I speak very well for myself. If you feel badly about making, or failing to make your own comments at a given time, then apologize as you will. I need no apology.

What you call "weird," is called speaking the truth. We have a preliminary report, as I so said. Not contestable, this is the fact. Not an opinion. We do not have a final report. We do not know what happened.

An initial landing g-load has been cited of 1.9 g, which would have been approximately 450 fpm vertical rate at touchdown. Boeing considers a pilot report of a hard landing as the sole criteria to qualify, but nearly all transport category airplanes will use a threshold of 600 fpm, or 2.4 g, to trigger an inspection. Boeing does not publish hard landing parameters, but one can look at design criteria and typical reporting criteria. The reported g load is insufficient data because it's more than just a single value; the rate for recording that must be determined via multiple data points at a minimum of 16/second, and the specific value experienced by the gear, with a moment apart from the long axis of the airplane depends on roll rate; it's amplified on the descending gear, by a substantial margin: the descending gear will impact the runway at a higher rate with a higher value due to the moment of rotation away from the axis of rotation. The gear hits harder. It doesn't take much rotation (roll) to case a significant rise in impact force. Moreover, while the design load for the gear is 340 fpm at max gross takeoff weight and 600 fpm for max gross landing weight, the implied descent rate for this mishap aircraft falls between those two values at the upper end of the design limit (on a linear scale between the two values). Based on those values, the flight would have needed to be approximately 160,000 lbs. or under, to remain within that linear scale. None of these specifics have been detailed in the preliminary report, so to suggest we "know what happened" is premature and incorrect. We do not. We have a little data and as is often correctly noted, a little knowledge is indeed a dangerous thing.

We are professionals; it is unprofessional to assume, speculate, guess, or jump to conclusions.

There is considerable data not yet presented, which will range from existing stresses imposed from prior operations on the gear trunion assembly and all associated components.. Lubrication and wear will be issues to consider, as will adherence to all work cards, inspection protocal and records, lubrication history (frequency, type, etc), and other factors that may have led to component failure. Not addressed thus far are side-load, repeat loading or shifting loads on the same landing, potential inconsistent braking due to surface conditions and anti-skid, and other related factors which will also impose uneven or additional loads (shimmy, etc, may be exacerbated by uneven braking or intermittent antiskid, or by gear truck condition).

Latching onto a few scattered data points to establish that you "know" what happened isn't "weird;" but a false statement made in ignorance of information not yet present. We have some information. We do not have all the information. We have a preliminary report. We do not have a final report. We do not have all the information.

A new trunnion assembly may handle a given load, but an assembly, including the failed trunnion pin, may not have that capability, depending on prior stress or damage, existing tolerance, corrosion, wear, etc. What that trunnion pin capability might have been a the time of occurrence, or what its status was in the course of its operational life, or what its maintenance, lubrication, or inspection history might be, we don't know, because we don't have all the facts. Accordingly, it's quite appropriate, and correct to say that we don't know, because we don't.

Last edited by JohnBurke; 09-16-2023 at 01:40 PM.
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Old 09-16-2023, 02:10 PM
  #82  
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Originally Posted by WHACKMASTER
He might be weird but at least heís consistent about it.

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APC needs to start charging him by the word.
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Old 09-16-2023, 02:57 PM
  #83  
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Originally Posted by Enginethunder
APC needs to start charging him by the word.
Better that someone contribute to the discussion, than someone who doesn't. Got something to offer?

I don't suppose anyone put a gun to your head and forced you to read it, did they? Too long, or just not enough pictures?
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Old 09-17-2023, 08:12 AM
  #84  
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Originally Posted by JohnBurke
Better that someone contribute to the discussion, than someone who doesn't. Got something to offer?

I don't suppose anyone put a gun to your head and forced you to read it, did they? Too long, or just not enough pictures?
I am appreciative of your use of paragraphs. It makes it much easier to read. Thank you.
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Old 09-17-2023, 06:49 PM
  #85  
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Originally Posted by Enginethunder
APC needs to start charging him by the word.
This is an utterly BRILLIANT idea!

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Old 09-17-2023, 08:59 PM
  #86  
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That would make you a pretty cheap date then, wouldn't it?

But then, based on your contribution to this thread, we already knew that.

Have you nothing to offer? Nothing at all? Don't answer that. It's rhetorical.
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Old 12-21-2023, 10:25 AM
  #87  
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Looks like N516AS just flew SNA-OKC yesterday. I assume to get some additional work done before re-entering service?
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