Minnesota Crash

[Shadrach]

11 hours ago, Nippernaper said:

It may seem counterintuitive, but it does seem like that's how wings typically fail.  See video link below of a cropduster pulling it's wings off.

 

That spar failed in the center of the fuselage in one place. The Minnesota Mooney failed just outside the main landing gear on each side leaving the center section intact. Totally different. The Embraer failed just as I would expect.

[Mooney in Oz]

How I respectfully wish that Ron Blum was still here with us to add his expertise to the NTSB final and thorough report 

[Nippernaper]

On 4/21/2023 at 9:19 PM, Shadrach said:

That spar failed in the center of the fuselage in one place. The Minnesota Mooney failed just outside the main landing gear on each side leaving the center section intact. Totally different. The Embraer failed just as I would expect.

Good point.  I guess I'm not too surprised that both wings can fail more-or-less simultaneously in a high g maneuver, as failure of one wing may not immediately result in an unloading of the other wing, especially if the rate of increase in the g loading is high.  In that case, even if the failure loads of the two wings differ, they probably are close enough that one failure will follow the other, if the loading is still increasing.

[Shadrach]

19 minutes ago, Nippernaper said:

Good point.  I guess I'm not too surprised that both wings can fail more-or-less simultaneously in a high g maneuver, as failure of one wing may not immediately result in an unloading of the other wing, especially if the rate of increase in the g loading is high.  In that case, even if the failure loads of the two wings differ, they probably are close enough that one failure will follow the other, if the loading is still increasing.

If one side failed first, the intact side would roll into the failed wing. The load on the remaining wing would absolutely change. This Mooney folded like a Corsair folding for storage. The symmetry of the failure is remarkable.

 

[EricJ]

When a spar, or anything stiff, breaks, the mechanics of the failure may send a shockwave or other energy through the rest of the system.   That energy impinging on another component that is also stressed nearly to failure may be enough to push it past failure.   It isn't surprising that the same point on the other side of a symmetric system would also be the same to fail.

 

[Pinecone]

If the rate of G increase is high enough, you could be well past the failure G by the time the failure progresses. 

So say one wing fails are 9G the other at 10G, but due to the G building so quickly, by the time the fractures progress, the wing is at 12G, you would see a pretty symmetrical failure.

[Nippernaper]

Looking through the NTSB database, where a structural failure has occurred prior to impact, failures of both wings do not appear to be especially rare. See below for an example from 2019 in a PA28:

The left aileron, outboard sections of the left and right wings, and the left and right
horizontal stabilizers were located about 1,500, 1,000, and 900 ft from the main wreckage, respectively.
Fractured areas of the left and right wings and the horizontal stabilizers were consistent with overload
separation before ground impact.

[hoot777]

NTSB report is out. Saw it in Plane and Pilot. Over 8g stress in a graveyard spiral. 

[LANCECASPER]

22 hours ago, hoot777 said:

NTSB report is out. Saw it in Plane and Pilot. Over 8g stress in a graveyard spiral. 

It's on this thread if you go back to March 23