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

 

[Garbage1]

I wonder if this proposed AD is related to Toronto Crash, and previously extended maintenance intervals allowed by FAA, as mentioned earlier in this thread? Interestingly this references an older Transport Canada AD.

"Summary​

The FAA proposes to adopt a new airworthiness directive (AD) for all MHI RJ Aviation ULC Model CL-600-2C10 (Regional Jet Series 700, 701, and 702), CL-600-2C11 (Regional Jet Series 550), CL-600-2D15 (Regional Jet Series 705), CL-600-2D24 (Regional Jet Series 900), and CL-600-2E25 (Regional Jet Series 1000) airplanes. This proposed AD was prompted by a determination that new or more restrictive aircraft maintenance manual (AMM) tasks are necessary. This proposed AD would require revising the existing maintenance or inspection program, as applicable, to incorporate new or more restrictive AMM tasks, as specified in a Transport Canada AD, which is proposed for incorporation by reference (IBR). The FAA is proposing this AD to address the unsafe condition on these products."

https://www.transportation.gov/regulations/federal-register-documents/2025-03526

 

[DirteJoe]

I'm more on the fabricstion side. Never completed my schooling for engineering or my A&P cert. Less stressful welding, machining, and casting for aero, petrochemical, and plastics/rubber industries in job shops. Made some friends on the maintenance side I keep in contact with. Almost went back to reschool for my A&P last year but life did not allow. Covid really threw a wrench in the works and I have not been officially in the aerosoace industry since March 2020; that was mostly DoD and civilian ground support tooling and custom tooling for maintenance techs.

 

[DirteJoe]

I wonder if this proposed AD is related to Toronto Crash, and previously extended maintenance intervals allowed by FAA, as mentioned earlier in this thread? Interestingly this references an older Transport Canada AD.

"Summary​

The FAA proposes to adopt a new airworthiness directive (AD) for all MHI RJ Aviation ULC Model CL-600-2C10 (Regional Jet Series 700, 701, and 702), CL-600-2C11 (Regional Jet Series 550), CL-600-2D15 (Regional Jet Series 705), CL-600-2D24 (Regional Jet Series 900), and CL-600-2E25 (Regional Jet Series 1000) airplanes. This proposed AD was prompted by a determination that new or more restrictive aircraft maintenance manual (AMM) tasks are necessary. This proposed AD would require revising the existing maintenance or inspection program, as applicable, to incorporate new or more restrictive AMM tasks, as specified in a Transport Canada AD, which is proposed for incorporation by reference (IBR). The FAA is proposing this AD to address the unsafe condition on these products."

https://www.transportation.gov/regulations/federal-register-documents/2025-03526

It is quite possible. There's an AD on corrosion at the PCU ball end for the elevator, and AD on structural cracks on wing elements that are being cracked down on recently I am hearing.

 

[Sym P. le]

Elevator and Rudder Power Control Units (PCUs) Rod End Fractures ...
CL-600-2D24

 

[DirteJoe]

TSB has released the prelim, though their web page is currently experiencing 403 errors. Photos of the landing gear are floating around snd the fractured area is at a known failure point.

Sinkrate warnings sounded 2.6sec prior to impact. Airspeed was decreasing quickly. N1 speed was 43% and unchanged. Right landing gear fractured and collapsed into the retracted position upon inpact. 136kt airpseed with 112kt ground speed at first sink rate alert, 134kt with 111kt ground speed at impact at about 1100fpm decent rate and a roll of 4.9*.

Cannot recall off the top of my head but 130-132kt at flaps 45 is the CRJ's minimum safe manuvering speed.

 

[Garbage1]

PDF of report

"At 1412:43.6, the right main landing gear (MLG) contacted the runway. The aircraft was in a 7.5° bank

to the right with 1° of nose-up pitch and 3g vertical acceleration, at a rate of descent of approximately

1098 fpm (18.3 fps)."

"The MLG shock struts on this aircraft are designed to absorb the energy of a 720 fpm (12 fps) descent

velocity at the maximum landing weight."

 

[LittleInch]

Post no 21 from our tame pilot said anything more than 3g and the undercarriage collapses.

Plane never flared, prob going too slow and just smacked into the runway so hard the gear collapsed. everything after that is just consequence.

Probably.

The failure line on the wing follows a set of bolt holes alright.

 

[Alistair_Heaton]

I don't think I did.

It's about that and there is plastic deformation in the main spar. Which may or may not cause the gear to collapse.

1100ft/min is a helva sink rate.

Around 5 Deg is normal flare attitude.

These numbers are above my experience line of survival from reports I have read.

 

[LittleInch]

Maybe I exaggerated.... But 3G was mentioned.

As most of us said at the start, they just flew this thing into the runway and at a rate above what the plane could handle. Why?

Nothing released so far says why but the PM ( captain) had only 3.5 hrs flying in the previous month??

 

[TugboatEng]

Wow, if really flattened the overhead. The bins are nearly touching the head rests.

 

[Garbage1]

It appears pilot talent limitaions are back on the table as a possible significant contributing factor, since 1100 FPM rate far exceeds 720 FPM design rate.

 

[DirteJoe]

Poor maintenance practices will also likely be brought up. Zinc phosphate rattle can on and around fasteners only means corrosion and repairs in the area.

 

[Garbage1]

Spar Shear image from preliminary report

 

[Sym P. le]

It seems the PF reacted to a "performance-increasing" wind gust by pulling back the throttle and then never recovered, though it may be normal procedure to reduce the throttle during the final stages of descent. The bottom fell out on the descent rate immediately thereafter. PF had more than 8 seconds to punch the throttles in recognition that the descent rate was out of scope. It looks like we needed a fly on the wall/wing to tell us what the IAS was doing between 12.30 and 12.40.

There is also a peculiar 9 knot drop in IAS across one second between 12.40 and 12.41. That would not help the situation.

At 1412:30, while the aircraft was descending through 153 feet AGL, its indicated airspeed increased to 154 knots whereas the ground speed did not change appreciably, consistent with a performance-increasing wind gust. The PF pulled back the thrust levers, and as a result, over the following 5 seconds, N1 decreased from 64% to approximately 43%, where it remained until touchdown. The airspeed began to decrease.

a hard landing is defined as “[a] landing at a vertical descent rate greater than 600 ft/min when the aircraft's gross weight is less than or equal to MLW [maximum landing weight]

	' AGL	IAS knots	descent rate fpm	% N1	ground speed knots	bank angle	pitch attitude (nose up)
12.01	500	150	720	64	121
12.26	175	144	672	64	121
12.30	153	154		64	121
12.35				43
12.40	50	145	1114	43	112
12.41		136	1100	43	111	4.7
12.42		136	1072	43	111	5.9
12.43		134	1110	43	111	7.1	1
12.43.6 td			1098	43		7.5	1

At touchdown, the following occurred: the side-stay that is attached to the right MLG fractured, the landing gear folded into the retracted position, the wing root fractured between the fuselage and the landing gear, and the wing detached from the fuselage, releasing a cloud of jet fuel, which caught fire. The exact sequence of these events is still to be determined by further examination of the fracture surfaces.

This is where my spidey-sense starts tingling. Though they close by offering a caveat regarding the sequence, they lead with the landing gear collapsing. I hope they take a close look at the video (my clip posted to Youtube here). I maintain that the landing gear had to be in place to cause the right wing tip to be thrust upwards before coming back down to the ground. The shearing of the wing spar (as the right MLG bottoms out) and ensuing upward deflection of the right wing tip would tear the side-stay connection.

Edit: Perhaps the side-stay broke off the landing gear first if the aircraft was not oriented with its forward motion. The side force would then leverage the gear and add additional complex loads on the wing (assuming the MLG could not extend outwards much past its vertical extension). What could not happen though is the gear collapsing to its retracted position.


Original animated GIF posted here.

 

[Garbage1]

I too don't see how they determined side-stay fractured upon landing impact, rather than fractured after the 'rear'wing spar failed, and as front wing spar and wing separated from fuselage.

Corrected above.

 

[Sym P. le]

The side-stay would fracture in close succession to the rear spar failure. The front spar would go later.

Regarding the spar shear image, I see a strong argument for fatigue failure.

The side-stay connection looks to be rather elongated, another clue!



From page 9 of the report, of course the right MLG bottomed out.

There was minor damage to the right MLG strut; marks on the lower portion of the right MLG strut outer cylinder showed evidence of the strut bottoming out.

 

[DirteJoe]

Optical illusion. If you pause this video at 54 seconds, there's a good shot of the side-stay with it's broken pieces.

 

[Sym P. le]

I don't know what kind of games the TSB is up to but it's rather juvenile. This frame has double stacked images, their Flickr account images are more akin to thumbnails than intelligent photos. They need to get a life and grow up.

 

[Sym P. le]

Right side-stay oriented as deployed, seen from the rear (note the hose fittings run along the aft surface). The schematics are of the left side, shown from the front. It has been removed from the fuselage, where it had remained attached. FWIW the video image is manufactured by cutting out the side-stay and pasting it over a background image.

Given the fracture and elongation of the connection hub, the MLG was pulled away from the centerline of the aircraft and aft which is not consistent with the MLG collapsing to its retracted position. Unfortunately, social media is running with the report indicating the gear collapse as the leading theory, caveats notwithstanding.

 

[Sym P. le]

I believe the image of the rear wing spar shows that it is substantially bent down from the wing surface, consistent with the fuselage punching down through the wing box with the landing gear firmly planted under the wing. The adjacent rib is creased accordingly (yellow dashed line). The wing trailing edge does not deflect downward since it is only substantially attached to the wing structure outboard of the MLG. I'd like to see the damage to the wing spar hidden by the rib.

Juan Brown (@blancolirio Youtube) estimates an impact force (at 3g) of 219,000 lbs. I believe the jury is still awaiting further evidence of what happened next.