https://www.ntsb.gov/Documents/Prelimiary%20Report%20DCA26MA024.pdf

Report pdf link if anyone is interested. Very interesting.

So what I see it not an engine failure, but a structural failure of the pylon right at rotation.

And yes two engines did go out, but I mean root cause.

NTSB said in their last onsite presser that the pylon separated with the engine. They alluded that the pylon was found disconnected from the engine, but that this was related to the engine striking the ground. They also talked in one or two of the pressers about pictures of the aircraft / engine leaving the aircraft. I would guess that these are the pictures/videos in reference.

It would appear a correct conclusion that some sort of structural failure occurred around the pylon / pylon connection points. I think it remaind to be seen how similar the failure was to AA191/DC-10 failure. The fact that the plane was already rotated and there is no visible smoke / fire until the engine is vertical / above the wing (pictures 1 & 2) would also appear to support that the engine was intact as the fire didn't break out until the fuel / hydraulic lines failed (pictures 3 & 4).

This also aligns with the FAA Energency Airworthiness Directives grounding all MD-11 / DC-10 variants citing concerns over the pylon. Also, the fact that both EAD's lack corrective actions to take to get the planes airborne again is very telling that something is very amiss here and someone at Boeing is worried enough about it being systemic to keep all these planes on the ground.

Those pictures show the failure to be eerily similar to AA191 - with the engine traveling over the wing just like 191. What's amazing to me is that 191 didn't have the same fire nor did the number 2 engine experience a compressor stall. 191 was more survivable than this one. Had that crew kept their airspeed up, they might have been able to save it. The left wing stalled b/c of the loss of slats - the crew had pitched for he trained-for airspeed which assumed the slats stayed deployed.

I think whatever corrective actions are suggested will functionally ground the fleet for good due to financial concerns.

Even if not, the timeline for grounding the fleet for inspection is already getting to be pretty long. Pilots need 3 landings every 3 months to maintain currency so FedEx is already starting to schedule simulators for pilots in Nov/Dec and then a follow up sim in Feb. That indicates they don't think this is going to be fixed in the next 3 months.
Couple that with the time-intensiveness of the inspection (400+ man hours/engine) and lack of equipment (can't move the airplanes so have to take inspection equipment to them) this is going to be a long road.

Plus, Captains need an in-aircraft check ride every 12 months that can't as of now be done in a sim. As soon as those start popping up this is going to domino.

That photo sequence is nothing short of extraordinary. Just wow.

TriAg2010 said:

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That photo sequence is nothing short of extraordinary. Just wow.

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As I said in another post, I think they have cameras tracking every take-off and landing.

Juan's video from today on the prelim report.

Aggie Jurist said:

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Those pictures show the failure to be eerily similar to AA191 - with the engine traveling over the wing just like 191. What's amazing to me is that 191 didn't have the same fire nor did the number 2 engine experience a compressor stall. 191 was more survivable than this one. Had that crew kept their airspeed up, they might have been able to save it. The left wing stalled b/c of the loss of slats - the crew had pitched for he trained-for airspeed which assumed the slats stayed deployed.

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I think AA actually did have a similar fire upon takeoff. Everyone has seen the 2 pics from the terminal with the plane sideways. Few have seen the pics take from a guy on another plane:



Here's the whole roll:



191 still had the slats in the wrong position and probably would have suffered a similar fate -- perhaps at a greater distance -- even if they had realized the plane was stalling. The report's conclusions included a reference to redundant systems to protect lifting components. (See Report at 70-71).

AA 191 Report

Now, had the pilots known the slats were in the wrong position and had enough altitude, they might have been able to overcorrect via the other engines (or possibly other techniques I'm unfamiliar with -- pilots can chime in) perhaps similar to United/Sioux Falls (can't remember flight number) with Aggie Al Haynes piloting. Obviously 191 got higher than the MD.

191 was climbing away fine at their takeoff safety speed as they're supposed to do in the event of an engine failure. The slats on the left wing retracted under air load and reduced the stall speed of that wing to less than V2 and it stalled and rolled them left into the ground. With the changes made after that the slats shouldn't retract on their own with a loss of hydraulics so it should have been survivable except maybe the fire. If they had known the slats had retracted they should have been able to pitch down and accelerate and avoid the stall and roll, nothing crazy like Sioux Falls required.

Airframe had almost 93,000 hours on it. That's over ten years in the air.

torrid said:

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Airframe had almost 93,000 hours on it. That's over ten years in the air.

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Not incredibly old. I personally have flown 3-4 with over 110,000 hours and at least one with 125,000.

torrid said:

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Airframe had almost 93,000 hours on it. That's over ten years in the air.

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Age and hours in the air isn't the most important metric when it comes to the condition of the aircraft.

It is the total number of cycles; a cycle being one takeoff, one landing.

It's just like with your car. Driving back and forth from Los Angeles to Jacksonville on I-10 puts a lot less stress on the vehicle than driving around town with the numerous stops and starts daily.

Also, older aircraft are safe as long as all of the proper maintenance is done. Eventually it simply because too expensive for the airlines and the aircraft is retired. Look at the B-52 and KC-135. Those are older than most of us on this forum. The B-52 will be flying into the 2050s.

In these workhorse aircraft, age and cycles go hand in hand. It's the age.

Whitetail said:

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https://www.ntsb.gov/Documents/Prelimiary%20Report%20DCA26MA024.pdf

Report pdf link if anyone is interested. Very interesting.

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That link didn't work. Hope this one does.

OK, it won't let me link directly to the PDF.

Click on the link on this page instead.
https://www.ntsb.gov/investigations/Pages/DCA26MA024.aspx

In Figure 10 showing the disassembled aft spherical bearing, it looks like corrosion pitting on the long bolt. Not sure if it is from long term corrosion, or from the post crash fire.

As Juan stated in his video, it is almost a certainty that the aft clevis and lug assembly's will need to be physically removed and examined for fatigue cracks to make the planes airworthy again. It may be cost prohibitive to do so though.

Excellent work [as usual] by the NTSB staff.

i wonder how this is going to impact inspection frequencies as well. not just in these aircraft but others.

if i understood right basically these pylon connections were still thousands of cycles away from being due to be inspected?

sts7049 said:

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i wonder how this is going to impact inspection frequencies as well. not just in these aircraft but others.

if i understood right basically these pylon connections were still thousands of cycles away from being due to be inspected?

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If I recall the numbers correctly, despite being over thirty years old this plane still had not hit the number of cycles that required an inspection. I would imagine that is an expensive and time-consuming process, requiring removal of the engine and the pylon.

torrid said:

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sts7049 said:

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i wonder how this is going to impact inspection frequencies as well. not just in these aircraft but others.

if i understood right basically these pylon connections were still thousands of cycles away from being due to be inspected?

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If I recall the numbers correctly, despite being over thirty years old this plane still had not hit the number of cycles that required an inspection. I would imagine that is an expensive and time-consuming process, requiring removal of the engine and the pylon.

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correct. This plane had +21k cycles. Inspection would've been required around 29k.

Longer grounding is now forecast by Western Global:

Quote:

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"During the past two weeks, WGA has been in constant communication with Boeing, who originally anticipated that by Nov. 14 they would have an approved noninvasive inspection protocol to return the aircraft to service. Because of this, we were hopeful that the MD-11 grounding would be short-lived. However, Boeing has now advised that more and highly invasive inspections, as well as repairs and parts replacements, would be required, resulting in an extended grounding of the MD-11 fleet for an undeterminable period of time," Romnios wrote.

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https://www.freightwaves.com/news/md-11-freighters-face-extended-grounding-for-inspections-airline-says

Either Boeing is being extremely cautious and covering every potential possibility, or the NTSB has a damn good idea of exactly why the failure happened.

Very possible it is both.

Feels like something as simple as:

"Initial testing showed this lug on the pylon needed inspection at 29,000 cycles. We just had a catastrophic failure at 21,000 cycles with no other obvious cause"

Would justify grounding the fleet to inspect at least a representative sample of the remaining MD-11 fleet. Which given the location of said lugs, would be a prolonged and expensive exercise.

Or they had a potential non-invasive way to examine the part and it yielded indeterminate or concerning results.

whats surprising to me is that a part that is fatigue limited wouldn't have a correct(?) damage theory associated life and appropriately conservative inspection interval.

the issue is less that it failed, more that it failed well within the prescribed inspection interval.

i'd be very curious what the number of cycles to failure were once a detectable flaw was initiated, what the estimated number of cycles to initiation were, and how that lines up with the inspection interval. that should be an afternoon of work for someone with FEA and basic material data.

anyone geeked up enough on this stuff to know what lifing theory would be used on that part? like safe-life part versus damage tolerance?

... for those less nerdy, everything has a life, things that have a life have an associated failure mode and inspection interval associated with that. when you're talking about fatigue, you have a period of time where the cycling of the part causes damage that's not detectable prior to initiating a crack. then you have a period where the cycling grows the crack until it hits fast fracture.

safe-life theory is that the part is retired when something like one in a thousand has initiated a crack.

damage tolerance assumes a crack is there, just below detectable limits (you can't see microscopic cracks), and then comes up with a life interval to inspect at a safe (conservative) interval, even if the crack was there when you started.

sts7049 said:

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i wonder how this is going to impact inspection frequencies as well. not just in these aircraft but others.

if i understood right basically these pylon connections were still thousands of cycles away from being due to be inspected?

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What is it about the Dc10/MD11 that makes this such a concern vs every other aircraft with underwing pylons/engines that I would think have a similar design?

Could be the specific fatigue specs of this part. Could be the specific materials and lifecycle associated with them. Could be the exact design based on number of lugs, etc. Could be the variable of introducing FOD into a tail mounted engine that isn't present on most other jets.

Or it could be that this is the second identical pylon failure in the history of the MD-11 and maybe they're concerned that they didn't get the failure mode correct on the last one. If it's true that it wasn't just improper maintenance for the last crash then that would make sense that they're a lot more concerned now.

Good explanation of the physics and materials science of the accident.

Scum sucking lawyers activated. Surprised it took them this long.

https://www.wave3.com/2025/12/03/were-prepared-do-whats-necessary-families-two-ups-plane-crash-victims-file-wrongful-death-lawsuits/

To be fair, an airliner falling on your head why you are going about your terrestrial day probably deserves a payday.

Now, given the names and nature of the businesses, how does this sort out if the are illegals?

flown-the-coop said:

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To be fair, an airliner falling on your head why you are going about your terrestrial day probably deserves a payday.

Now, given the names and nature of the businesses, how does this sort out if the are illegals?

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On the fist point, yes, but this law firm makes their living suing everyone involved in plane crashes, regardless of blame/cause knowing most companies will just pay them off to go away. The cause could end up being the maintenance company used an unapproved replacement part which failed, and they'll still demand multi-millions from Boeing and GE. And right now, there is no evidence the engine caused the failure (a P&W or RR engines would have come off just the same) so suing GE is 100% a money grab.

As for #2, they'll get paid even if they're illegals, and probably protection from deportation.

Believe it or not, the Texas Supreme Court ruled fifteen years ago that illegal immigration status and lying about that status cannot be raised in a civil suit as it is always irrelevant and improper impeachment evidence.
TXI Transp. Co. v. Hughes, 306 S.W.3d 230, 240 (Tex.2010)

If it were up to me, the civil courthouse would not be available to plaintiffs illegally in the country (just like they cannot serve as jurors, attorneys or judges).

Jetpilot86 said:

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Good explanation of the physics and materials science of the accident.

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Im no pilot and don't know much about planes other than flying commercial fairly often, but after watching the video, it seems like there should / needs to be a better way to inspect the entire engine attachment system

the guy is saying that this airplane basically was never designed for long term (long long term) use as a freight carrier that handles heavier cargos on a continual basis. thus heavy loading the lugs/brackets eventually gave way and there was no real way to check them because of their location (they were hard to look at).

So my very simple question, wouldn't or should there be a maintenance requirement where the entire engine lugs / bearings, etc. connection system must be totally replaced? seems to be a rather simple requirement to replace all of that engine connection system? I do have an engineering degree and stuff like this bothers me, maybe it is not as simple as it seems based on this type of analysis otherwise it would have been fixed already

Not terrible, but a bit dramatic/doomsdayish.

FWIW, this is when it would have been checked next:

Airplane Cycles : 21,043 (actual)
Clevis Support Inspection next due : 28,000
Pylon Aft Mount Lugs Inspection next due : 29,200

My point is that there are/were scheduled inspections of the lug mounts for fatigue cracks/signs of wear etc on the bearings. Aircraft accidents are generally a result of multiple complex failures, due to the depth of failure modes/service requirements. Metallurgical failures are quite common contributory causes, and as seems obvious was a main contributor here, but the basic design (and freighter conversion/application) really in and of itself was not a 'uniquely difficult to inspect part so they just don't do it.' Could inspection/replacement be ordered much more frequently as a result of this investigation? Sure. Supposedly, and I could be wrong on this, it takes a combined 100 or so man hours to do the full inspection (remove engine etc).

My unsolicited opinion is that Fedex/UPS are going to get real tired of paying their 577 or so trijet pilots (they are still getting full pay due to union contracts) sometime after Xmas toward Feb, and I don't think it's too likely anything like a full return to service happens next year for these 50-ish planes. There is a real shortage of cargo aircraft in this size category (Boeing 767F is ending production at end of 2027, as is the 77F due to environmental restrictions etc).

Incredibly, the only new-build freighters (Boeing has long had over a 90 percent market share) are going to be the A330F, and A350F for a bit (778F, and then a likely 787F version toward the 2030-ish timeframe), but don't feel too bad for UPS/Fedex, they had the option to buy more 767F (even a 767-400ER derivative was offered), and 747F as well but declined.

ETA: Fedex is a total trainwreck at this point, not really directly related. Their all-Indian ethnic executive suite really is going to destroy the company, imho.
https://fdx.alpa.org/Portals/7/Documents/communications/public/2025/12/2025-12-02-mec-chair-message.html

I was curious so I looked. The ceo is Indian and worked his way up through the ranks, similar to Kawal Preet. Looks like a balanced board to me?


https://www.fedex.com/en-us/about/leadership.html

Look at the CEO's staff, among other data points.

Mrs. Jerk noticed that FedEx's legendary reliability collapsed in the last few years. (She uses them for shipping large quantities of perishable medical supplies. )

Their suddenly-poor performance was a frequent topic of our evening cocktail conversation. She thought it was… https://t.co/tQjGTe1jnj

— Dr. Insensitive Jerk (@DrInsensitive) October 6, 2025