Toronto place crash 4

[LittleInch]

A Delta plane appears to have touched a wing tip during landing, ripped the wing off then promptly flipped over onto its back.

As they were on the airfield and this time didn't run into anything or catch fire, everyone is alive, though not surprisingly some injuries.

All passengers survive crash landing as plane flips at Toronto airport

Eighteen of the 80 people on board were injured after the Delta plane overturned on landing.

www.bbc.co.uk

This video https://www.dailymail.co.uk/news/article-14407855/delta-plane-crash-toronto-fireball-footage.html makes it look like a very hard landing - no visible flare

 

[GregLocock]

From the flight data I get 848 fpm descent rate, or just over 4.3 m/s

 

[TugboatEng]

Having a lot of right stick would be a contributing explanation of how the wing failed with only 850 ft/m sink rate in the fuselage.

 

[XR250]

It's crazy to me that this joint supports the wing loads/ landing forces. Looks pretty weak.

 

[mfgenggear]

This post maybe mute. But the designers did something right was keeping the passengers alive. Maybe the wing attached to the fuselage
Is probably weak for a reason.

 

[DirteJoe]

I'm suspecting it's a weak point more due to maintenance practices and difficulty, as it seems to be the case with other MLG and wing/fuselage fastening points.

Coming in on a 5* slope and not flaring is still pretty extreme of a landing.
However photos are starting to pop up in various outlets showing the inboard snd outboard tires of the MLG are intact. Not close enough to determine just what state they are in, but enough to show them intact and not debeaded.

 

[LittleInch]

There's a lot of bolts there....

It doesn't seem to be a known failure so prob corrosion or damage or a few missing nuts...

 

[LittleInch]

This post maybe mute. But the designers did something right was keeping the passengers alive. Maybe the wing attached to the fuselage
Is probably weak for a reason.

I bloody hope not. I really really don't want the wings to fall off in extreme turbulence.

 

[mfgenggear]

I agree, I watched Boeing and airbus test their aircraft wings. it's a good video to watch. Airbus was very confident of their design and builds.

 

[DirteJoe]

There's a lot of bolts there....

It doesn't seem to be a known failure so prob corrosion or damage or a few missing nuts...

All depends on exactly where the break began.

Could be a red herring but that bulletin on the fuselage/wing attachment leading to a possible loss of a wing due to 1 or 2 attachment points failing from nuts working their way out raises some eyebrows.

 

[SWComposites]

that photo does not show the entire assembly. among other things, the entire wing skins are not yet installed.

yes, transport aircraft wings are designed for loads way beyond what a normal flight would see.
787 wing ultimate static test:

Boeing 787 Passes Incredible Wing Flex Test

Boeing has completed one of the more spectacular tests of the 787 Dreamliner program. The airplane maker completed the “ultimate-load wing-up bending test” on Sunday using airframe ZY997, the test aircraft that is basically built to be tortured on the ground and never fly. During the test, the...

www.wired.com

https://www.reddit.com/r/pics/comments/2sqnf8/boeing_787_wing_stress_test

the AD on the CRJ is likely misleading. transport aircraft are designed to damage tolerance requirements and loss of a single fastener is not going to be catastrophic.

 

[Brian Malone]

~25 ft deflection - quite impressive. The testing fixture is quite amazing itself. I image the wing has a gazillion strain gauges attached and the harnesses for these alone would be a major engineering task.

 

[TugboatEng]

The follow-up claims that the 787 wing was never tested to failure while the 777 was. Ok, the 777 wing visibly broke but I would think any plastic deformation would be failure. Was the 787 tested to yield? The 787 is composite, is there any yield?

 

[TugboatEng]

Also note that the wing loading tests are simulating the uniform loading of lift (which is why they are so complex). A runway landing gear impact is more of a concentrated load. I would expect less deflection at failure due to the load being much closer to the anchor point, cantilever.

 

[SWComposites]

787 was tested to ultimate loads (limit * 1.5), plus I think a bit more.
Composites essentially do not “yield”, the stress-strain response is generally linear to failure. Bearing stress-displacement can be non-linear.

 

[Sym P. le]

Some graphical musings regarding the evacuation of the wing structure (using previous images flipped, rotated, and inside out to ease the mental gymnastics). We see the remnants of the lower wing skin? I wonder why the skin stiffening rib is held back near the curved tear out. A likely access panel? There seems to be a gap in the main gear bracket (green leaders)?

At any rate, it appears the main gear web reinforcement on the spar (or the bracket gap) delineate the shear line for the lower chord of the wing spar.

The build it video shows what seems to be trailing edge / main gear subassemblies and fittings waiting to be included in the wing frame. I can't tell how it all fits together.

Disclaimer: A previous image I marked up was wrong (here) and these could be too! User discretion advised.

 

[SWComposites]

Sym, I'm quite familiar with wing structures, but I have no idea what you are trying to show with the pink and green lines.

 

[SWComposites]

This is the MLG configuration, it folds inwards, with all of it mounted aft of the wing rear spar:


the fore-aft beam shown above is just outboard of the trunnion, which mounts in bearings in the rear spar and aux spar/fitting (grey in image below).

this is the wing box internal structure from the video (skins are not installed). I've added the trunnions (orange), main gear posts (red) and tires (blue) in the folded positions.



Lastly, this simulation view shows how the a/p is supposed to land:

 

[Sym P. le]

Thanks for speaking up. The pink line attempts to represent the torn edge of the wing skin, which we see in the crash evacuation video and photo, while the green leaders were to highlight the curious gap in the MLG bracket or assembly, which I had thought (I've changed my mind) played a role in where the lower spar flange tore. I now think what we are seeing at the trailing edge of the wing skin panel is not any part of the spar, just the skin covering. I hope I'm starting to make some sense. If you can better explain the photos, I'm all ears.

Some photos of the wing underside which show a possible access panel in the appropriate location, as well as numerous others.