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

 

[DirteJoe]

How do simulator training programs handle hard landings? Are therr typically any limits on landing hard and being given a failing grade?

 

[Garbage1]

Perhaps not enough 'voltage' feedback to stimulate learning from failure?

 

[waross]

144kias

144 Knots Indicated Air Speed??

 

[LittleInch]

144 Knots Indicated Air Speed??

yes

 

[Alistair_Heaton]

You get to see it in the SIM when you do a windwind shear at flare height and don't follow the wind shear escape manoeuvre.

It just goes bang and the screen blanks out. And a number is called from the back.

I have only seen it do it once.. And it was a new first type first officer. I did a singular "I have control" during an out of limits approach and just got told "box ticked for you, for Captaincy" And apart from the minimum required for requalification for me the FO was manually flying for both 4 hour sessions.

A marked improvement was seen.

 

[Sym P. le]

I believe the wing spar slots into the space between the heavy landing gear bracket and a lighter reinforcing piece, indicated by the arrow. The upper 3D image is taken from the TSB video and rotated 180 degrees so we're looking at the lower wing skin remnant (mirrored). We can also see the spar flange torn along the fastener holes and a stub of reinforcement (circled). The wing rib, at least this one, is attached to the skin with a series of tabs, which tore off the rib.

Of interest is the depth of slot as determined by the outline on the recovered spar. Also, the spar tore straight out of the slot with barely any damage to the lighter reinforcement plate. This indicates the spar web failed in tension as the structure pivoted about the fuselage interface (star) while the flange sheared along the fasteners.





On another note, I estimate the spar is deformed over 12", maybe even 14". I used the open spoiler as a reference, being about 45", scaled from a reference drawing in the CRJ-900 Airport Planning Manual, here. In the following image, the line of the spar is indicated in blue (it's easy to cross-reference the wing coloration with other images). The deflection extends as far back as the MLG rib. There can't be any doubt left, the landing gear was not the cause of the calamity.

 

[Alistair_Heaton]

Excellent work sir.

I am not surprised on your findings though.

You just need to get near one in real life to understand they are not the weakest link.

Quite often they are the only thing left after an accident.

 

[DirteJoe]

The slot is a section of cruciform plate.

TSB's images do state the exact sequence of events has not been determined yet, so I don't think they're off on the wrong foot missing the obvious reasons.

 

[LittleInch]

I have no idea what I'm looking at anymore, but the conclusion seems good to me, i.e. the impact with the ground on one wheel basically exceeded the wings capacity and it found the weak spot. Once that went it all cascaded from there.

 

[DirteJoe]

Basically. Only thing not known yet is would the wing have failed in an undamaged state, or was there previous damage or manufacturing/repair issues that lead to the hard landing being even worse. The gear bottoming out hard yet still being functional and at the correct nitrogen charge is a bit surprising to me.

It seems like there is not a system in place that records data to be able to trace back hard landings, or is there? Wonder how many hard landings the wing structure can take before it wants to give up the ghost. It would be far from cost effective but should not be overly difficult to certify and retrofit linear travel sensors to the MLG and NG, record the data, and be able to trigger an inspection needed warning light after sensing near or complete travel of the strut. I doubt most flight agencies would approve the use of zip-ties on the chrome as a travel sensor but that'd work just as well.
As soon as that right MLG bottomed out it was game over.

Still never would have expected a crew to disconnect the AP, never correct throttles, and just sink it into the ground, let alone one of the crew allowing it being a training instructor. Seems very much like a lot of foreign flight training programs where failure is not an option and bad habbits are reinforced in a quest for money over safety.

 

[Garbage1]

And so much more could be learned by trainees in simulations, if they were pushed to breaking points. Kinda like the professors where whole class fails, then learns from failure by going over failed test, and requiring grades have to be scaled

If failure is not an option with real consequences, then trainees are not prepared for all possible scenarios, and have not learned as much or discovered their limits.

Time is not on their side in off nominal / emergency situations, and they have to act instintively and decisively, from having practiced lots of challenging simulation scenarios. Ones that cause initial failure, and create problem solving critcal thinking, and learning opportunities.

 

[Sym P. le]

My apologies for the mental gymnastics with the flipped and mirrored images, they are a challenge.

I've worked with aluminum plate and wouldn't call it weak. Certainly orders of magnitude greater than milk toast. Aside from the oleo, it is only fortunate the structure had avenues to absorb so much energy and all survived.

Regarding the failure mode of the spar web, it's the sum of all stressors, not purely tension or shear (though ultimately, it is diagonal tension that breaks it). Tension seems to have played a significant role.

My curiosity abounds. I need a designated cat.

 

[DirteJoe]

Once you start work hardening that aluminum with repeated abuse, it's crack city and I'd definitely call it weak, especially around poorly chamferred bolt/rivet holes. Not that it really matters in this case.

 

[Sym P. le]

That could be a key factor in this case. There is no practical way to examine that portion of the spar for ongoing abuse.

 

[DirteJoe]

If that is the cruciform I think it is, 2 teams of 2 could remove fasteners and the cruciform for inspection and reassble in 2 days. Easily could be done while other service work is getting performed.

Fuel tanks are still commonly inspected by having some poor sap squeeze through an access port and belly crawl through. Airline maintenance doesn't have practicality all the time. I'd rather fight with special tools in a cramped wing section than that.