Originally explained on the blancolirio channel on YouTube -
The timing and manner of the break make a lot more intuitive sense when you consider that the engine is essentially a massive gyroscope. As the plane starts to rotate, the spinning engine resists changes to the direction of its spin axis, putting load on the cowling. When the cowling and mount fail, that angular momentum helps fling the engine toward the fuselage.
Yup. That's exactly what experts said of American Airlines flight 191 which was basically the same engine mount, same failure. Engine flipping over the wing.
Flipping backwards is what caused the engine to fly to the right and land to the right of the takeoff runway. The stills in the NTSB preliminary report clearly show the engine flying over the aircraft, to the right, and then heading straight down.
Yes, obviously; MD-11s aren't flinging engines off the wing every single takeoff. A 34 year old airframe may or may not actually match design strength, though.
Yes, but the point is that this moment of the takeoff is when a failure that's been waiting to happen is most likely both because of the thrust and the gyroscopic resistance.
Grounding all MD-11s and DC-10s is a major move. I guess it makes sense as a big factor was the fatigue cracks on the pylon (lugs), despite the pylon not being behind on inspections. I am wondering what the inspections of pylons in other planes will yield, likely that will determine whether the grounding will continue.
But beyond figuring out why the engine mount failed, I am very interested in what caused the actual crash. "Just" losing thrust in a single engine is usually not enough to cause a crash, the remaining engine(s) have enough margin to get the plane airborne. Of course this was a major structural failure and might have caused additional damage.
EDIT: It seems there was damage to the engine in the tail, even though this was not specified in the preliminary report, likely because it has not been sufficiently confirmed yet.
And if the failure of a wing engine can cause the rear engine to fail, that would raise concerns about all "two in front one in back" trijets. Similar to how putting the Space Shuttle orbiter's heat shield directly in the line of fire for debris that comes off he rocket during launch turned out to be a bit of a problem.
At this point there aren’t any trijet designs like that being built, and it’s unlikely we’ll ever see a new trijet design. It served a role in the transition from four engines to two, but now with ETOPS-370 there’s no commercially viable route that can’t be served with an appropriate twinjet.
And the failure of an engine mounted on the left wing can cause debris to cross through the fuselage structure and cause a failure of the engine mounted on the right wing, or to fly thousands of feet in any particular direction, as happened to American Airlines in both a ground run incident, and in their Flight 883 accident.
Yeah, the trijet design seems failed in general. Unless you can design it to tolerate any wing+tail dual engine failure -- in which case, why have the tail engine at all?
At some point it comes down to probabilities. With so many flights going on, one in a million incidents become a certainty. For example UA232 [1] suffered failure in all 3 redundant hydraulic systems due to an uncontained engine failure. Any of the 3 systems would have been enough to retain control of the aircraft. Of course this lead to some investigations on why all 3 systems could be impacted at the same time and what can be done to limit failures.
Besides the technical aspects that flight is an impressive example of resilience and skill. Bringing that plane down to the ground in nearly one piece was essentially impossible and a one in a million chance in itself.
Even if they end the grounding of the MD-11/DC-10 I'd be shocked if any airlines still using them will continue to use them.
Seems like the risk/reward just isn't really there for the few of them still in service, and if anything happened it would be a PR nightmare on top of a tragedy.
UPS and FedEx each have around 25 MD-11s, Western Global has 2 I think, the Orbis Flying Eye Hospital is an MD-10, some cargo airline in Botswana has one, and 10 Tanker has some DC-10 firefighting tankers.
Given that the report only mentioned a single other seemingly related accident in 1979 I am not sure that objectively this is a reason to discontinue flying these planes. The fact that these planes have been in service since the early 70s is a testament to their safety and reliability in itself. Of course public perception, especially with the videos of huge fireballs from hitting one of the worst possible locations, might put enough pressure on airlines to retire the planes anyway.
I agree on the end of an era. Hearing something else besides just Airbus- or Boeing-something always gives me a bit of joy. Even though MDs and DCs are of course Boeings in a sense now as well.
I think that the Mad Dogs only exist as freighters (~or their derivative KC-10 tankers~-Edited to correct that they retired last year) these days. I think the last pax service for any of them was over a decade ago.
And air freight just gets a lot less public attention, I think they are going to keep flying them if they don't get grounded.
It wasn't just one engine off, aside from possibly damaging tail engine you also have damage to the wings and control surfaces that might've just not got enough lift because of that.
> EDIT: It seems there was damage to the engine in the tail, even though this was not specified in the preliminary report, likely because it has not been sufficiently confirmed yet.
Yes, the initial videos were showing the tail engine flaming out. And in the 1979 crash, the engine also severed hydraulic lines that hold the slats extended. So they folded in due to the aerodynamic pressure, essentially stalling the wing.
Based on the original descriptions of the crash, I assumed the engine fell off.
From the photos, it’s clear it went up over the wing and impacted the fuselage with a (at least) minor explosion, which would have thrown foreign objects into the third engine in the tail for sure.
Losing 2/3 of the engines isn’t survivable on takeoff for this class of plane, at the weights they were at.
It's an engine - the thing pushing the entire plane forwards. Provided it is running (and at takeoff that's definitely the case), an engine being liberated from its plane suddenly has a lot less mass holding it back, so the logical thing to do is to shoot forwards. And because the wing is attached to the upper side of the engine, anything short of an immediate failure of all mounting points is probably also going to give it an upwards trajectory.
Add in air resistance, and you get the "swing across the wing and back" seen in the photos.
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That's a pretty nice message. Most sites that filter VPNs and proxies just kill the connection, give a generic error, or subject you to endless captchas.
> On the aft lug, on both the inboard and outboard fracture surfaces, a fatigue crack was observed where the aft lug bore met the aft lug forward face. For the forward lug's inboard fracture surface, fatigue cracks were observed along the lug bore. For the forward lug's outboard fracture surface, the fracture consisted entirely of overstress with no indications of fatigue cracking
If I'm parsing this correctly, they're saying that fatigue cracks should have been visible in the aft pylon mount, and that the forward mount was similarly fatigued but showed no damage on the outside?
> If I'm parsing this correctly, they're saying that fatigue cracks should have been visible in the aft pylon mount, and that the forward mount was similarly fatigued but showed no damage on the outside?
If you can get to the report, Figure 7 shows the left pylon, with the forward and aft lug enlarged in the inset. Both lugs cracked on two sides. They're saying both cracks on the aft lug as well as the inboard crack on the forward lug were observed to be fatigue cracks, but the forward lug outboard fracture was observed to be entirely a stress crack.
Outboard and inboard are just away from and towards the center of the plane. On the left pylon, that's left and right, respectively. So, it looks like the left side crack in the forward lug developed from overstress, but the other three cracks were from fatigue. My expectation is that fatigue should be apparent upon the right kind of inspection, if timely, even if the metal has yet to fracture.
Very fast. Quite sad to see it happen. Also quite puzzling is how the Air India disaster still does not have a root cause analysis done (though supposedly it will be released end of this year)
> Also quite puzzling is how the Air India disaster still does not have a root cause analysis done
Nothing puzzling. Straight-up cover-up.
Now, the interesting part would be to know what is being covered-up. Pilot error? Pilot suicide? Or a critical system malfunction Boeing cannot afford?
The Indian authorities has blamed the pilots in every single crash. AND there is not enough evidence to guarantee that was the case. It is one of many possibilities.
These all seem like OCR errors...? Why would there be OCR in this workflow? Did they print this out and then generate a PDF from a scan instead of the original source? To maintain an air gap maybe?
TIL about this eerily similar DC-10 crash in 2011:
Shortly after liftoff, 20 feet (6.1 m) above and 7,000 feet (2,100 m) down the runway, the No. 2 engine separated from the wing and struck the No. 1 engine's inlet cowling, causing it to produce drag and reduced thrust. Even with full right aileron and rudder, the plane started to descend and drift to the left. The captain lowered the nose and leveled the wings, which was followed by the plane making multiple contacts with the runway. After touchdown, the plane drifted left and departed the runway, crossing a taxiway before coming to rest in a saltwater marsh. A fire erupted which consumed the top of the cabin and the cockpit. All three crew members survived.
...is this a bot comment? The accident you linked is very clearly of a Boeing 707, which has zero relation to a DC-10 and is most decidedly not a trijet.
40 years between severe accidents is fine in terms of expected failures. It's also not a good comparison because in the 70s maintenance crew were using a forklift to remive engines, improperly stressing the engine pylon. This was done as a shortcut
Rather the opposite: if the cause is similar to AA 191, why weren't the actions taken after AA 191 to prevent a repeat effective? If we can get a repeat of that incident, what's preventing the industry from repeating the mistakes from all those other incidents from the past decades? Why aren't they learning from their past mistakes - often paid for in blood?
> The referenced AA Flight 191 is shockingly similar. It makes me wonder if aviation really is back sliding into a dangerous place.
I think it's cut throat capitalism at its best. Surely it was much too safe before, let's see how far back we can scale maintenance on the operations front but also how far back can you scale cost during development and production and then see where it takes us. If that changes the risk for population from 0.005 to 0.010, the shareholders won't care and it's great for profits.
I think we can see both but especially the latter with Boeing.
The entire MD-11 project was a budget-limited rush-job to try to capture some market share before the A340 and 777 came into service.
It produced an aircraft that failed to meet its performance targets, was a brute to fly and was obsolete the moment its rivals flew.
Douglas* by the early 1990s was a basket-case of warmed-over 1960s designs without the managerial courage to launch the clean-sheet project they needed to survive.
El Al 1862 was another flight [1] that had an engine fall off, taking another engine out with it. The pilots managed to fly around for a few minutes and attempt a landing, but there was too much structural damage.
It doesn't seem aircraft are designed to survive these types of catastrophic failures.
They seem to have lost the tail engine too. Yes, it is a significant problem that engine failures aren't independent, so trijets are kind of a bad design.
Not only did it happen at the worst possible moment, it took out a second engine on it's way out and over the plane. Two engines should've been enough to get off the ground and potentially land the plane, but one engine on a trijet isn't enough.
From the wing down I assumed it may have depended if the engine coming out unintentionally means redundant hydraulic lines and mounts are also getting disconnected causing a complete loss of control not that it would have helped much at that point beyond minimizing ground damages.
Yeah, pilots I know saw puffs of flame coming out of the engine, and said that that's a tell-tale sign of a compressor stall. Which could have been caused by debris from the separating left engine striking the turbine.
I'm surprised at how many years the plane went without having that part inspected. It looks like the failure was due to fatigue cracks, but the last time the part was inspected was in 2001?
I believe the part was at least visually inspected in 2021:
> A review of the inspection tasks for the left pylon aft mount found both a general visual inspection (GVI) and a detailed visual inspection of the left pylon aft mount, required by UPS's maintenance program at a 72-month interval, was last accomplished on October 28, 2021.
As I told my friends, this preliminary report annoys me. It annoys me for the same reason it seemingly annoys the NTSB: American 191 is nearly identical on the surface, right down to the engine detachment and resultant loss of the aircraft, in almost the exact same spot on the airframe, ~45 years later.
Needless to say they’re going to be scrutinizing everything to determine what the cause is and the sequence of events that created the accident, but I also suspect everyone involved is just as annoyed at this as I am, given that this exact situation should have been fixed already.
Gyroscopic precession took the left engine to the right. In AA 191 the right engine departing to the right did not affect the center engine. Sadly the engine failure procedure at the time mandated slowing down to V2 which was below the stall speed with slats retracted. There's now revised procedure and hydraulic fuses.
I expect all remaining aircraft will be getting new rear pylon lugs with shortened inspection intervals - provided the replacement cost is below the value of continued usage.
Looks like it's been moved to https://www.ntsb.gov/investigations/Documents/DCA26MA024%20P...
Originally explained on the blancolirio channel on YouTube -
The timing and manner of the break make a lot more intuitive sense when you consider that the engine is essentially a massive gyroscope. As the plane starts to rotate, the spinning engine resists changes to the direction of its spin axis, putting load on the cowling. When the cowling and mount fail, that angular momentum helps fling the engine toward the fuselage.
I think far simpler explanation is "the back part failed first and engine is making thrust so it just flipped over on now-hinge mounting
That's why it flipped upwards, but not why it flipped towards the body of the plane / to the right.
4 replies →
Yup. That's exactly what experts said of American Airlines flight 191 which was basically the same engine mount, same failure. Engine flipping over the wing.
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Flipping backwards is what caused the engine to fly to the right and land to the right of the takeoff runway. The stills in the NTSB preliminary report clearly show the engine flying over the aircraft, to the right, and then heading straight down.
There might be some truth in that. But the report doesn't confirm that theory.
What theory? That the mount failed? Or the rotation of the engine in the photos going up and over the fuselage?
It seems like both are true, but doesn't necessarily prove WHY the mount failed.
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I'm presenting it "useful not true" - not an RCA.
This is a preliminary report. Its purpose is to present initial evidence/information.
The final reports are always much more comprehensive.
I assume such forces are calculated and added in when deciding hot thick to make those mounting brackets.
Yes, obviously; MD-11s aren't flinging engines off the wing every single takeoff. A 34 year old airframe may or may not actually match design strength, though.
Yep. Now do 3 decades of metal fatigue.
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Yes, but the point is that this moment of the takeoff is when a failure that's been waiting to happen is most likely both because of the thrust and the gyroscopic resistance.
Aluminum has limited loading cycles
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Grounding all MD-11s and DC-10s is a major move. I guess it makes sense as a big factor was the fatigue cracks on the pylon (lugs), despite the pylon not being behind on inspections. I am wondering what the inspections of pylons in other planes will yield, likely that will determine whether the grounding will continue.
But beyond figuring out why the engine mount failed, I am very interested in what caused the actual crash. "Just" losing thrust in a single engine is usually not enough to cause a crash, the remaining engine(s) have enough margin to get the plane airborne. Of course this was a major structural failure and might have caused additional damage.
EDIT: It seems there was damage to the engine in the tail, even though this was not specified in the preliminary report, likely because it has not been sufficiently confirmed yet.
And if the failure of a wing engine can cause the rear engine to fail, that would raise concerns about all "two in front one in back" trijets. Similar to how putting the Space Shuttle orbiter's heat shield directly in the line of fire for debris that comes off he rocket during launch turned out to be a bit of a problem.
At this point there aren’t any trijet designs like that being built, and it’s unlikely we’ll ever see a new trijet design. It served a role in the transition from four engines to two, but now with ETOPS-370 there’s no commercially viable route that can’t be served with an appropriate twinjet.
3 replies →
And the failure of an inboard wing mounted engine can cause the failure of an outboard wing mounted engine on the same side, as in the case of El Al 1862. https://www.faa.gov/lessons_learned/transport_airplane/accid...
And the failure of an engine mounted on the left wing can cause debris to cross through the fuselage structure and cause a failure of the engine mounted on the right wing, or to fly thousands of feet in any particular direction, as happened to American Airlines in both a ground run incident, and in their Flight 883 accident.
https://www.dauntless-soft.com/PRODUCTS/Freebies/AAEngine/
https://aerossurance.com/safety-management/uncontained-cf6-a...
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Yeah, the trijet design seems failed in general. Unless you can design it to tolerate any wing+tail dual engine failure -- in which case, why have the tail engine at all?
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At some point it comes down to probabilities. With so many flights going on, one in a million incidents become a certainty. For example UA232 [1] suffered failure in all 3 redundant hydraulic systems due to an uncontained engine failure. Any of the 3 systems would have been enough to retain control of the aircraft. Of course this lead to some investigations on why all 3 systems could be impacted at the same time and what can be done to limit failures.
Besides the technical aspects that flight is an impressive example of resilience and skill. Bringing that plane down to the ground in nearly one piece was essentially impossible and a one in a million chance in itself.
[1] https://en.wikipedia.org/wiki/United_Airlines_Flight_232
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Even if they end the grounding of the MD-11/DC-10 I'd be shocked if any airlines still using them will continue to use them.
Seems like the risk/reward just isn't really there for the few of them still in service, and if anything happened it would be a PR nightmare on top of a tragedy.
Definitely an end of an era!
UPS and FedEx each have around 25 MD-11s, Western Global has 2 I think, the Orbis Flying Eye Hospital is an MD-10, some cargo airline in Botswana has one, and 10 Tanker has some DC-10 firefighting tankers.
That’s the entire worldwide fleet.
Given that the report only mentioned a single other seemingly related accident in 1979 I am not sure that objectively this is a reason to discontinue flying these planes. The fact that these planes have been in service since the early 70s is a testament to their safety and reliability in itself. Of course public perception, especially with the videos of huge fireballs from hitting one of the worst possible locations, might put enough pressure on airlines to retire the planes anyway.
I agree on the end of an era. Hearing something else besides just Airbus- or Boeing-something always gives me a bit of joy. Even though MDs and DCs are of course Boeings in a sense now as well.
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I think that the Mad Dogs only exist as freighters (~or their derivative KC-10 tankers~-Edited to correct that they retired last year) these days. I think the last pax service for any of them was over a decade ago.
And air freight just gets a lot less public attention, I think they are going to keep flying them if they don't get grounded.
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Airlines haven't been using them, or at least not 1st world airlines. Just freight and wilderness fire fighters.
Most of them are used as cargo planes. Which have dramatically lower usage rates than passenger planes (and they are retired passenger planes)
Sucks for the pilots flying them for sure tho.
> Grounding all MD-11s and DC-10s is a major move
Not really. There are zero left in passenger service, they pretty much only serve cargo now.
Losing cargo jet capacity right before the holidays may cause some issues.
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It wasn't just one engine off, aside from possibly damaging tail engine you also have damage to the wings and control surfaces that might've just not got enough lift because of that.
Captain Steeeve thinks it was actually the starboard engine that also failed due to evidence of compressor stalls in some of the footage
https://youtu.be/CmXLQHhUtv4?t=499
> EDIT: It seems there was damage to the engine in the tail, even though this was not specified in the preliminary report, likely because it has not been sufficiently confirmed yet.
Yes, the initial videos were showing the tail engine flaming out. And in the 1979 crash, the engine also severed hydraulic lines that hold the slats extended. So they folded in due to the aerodynamic pressure, essentially stalling the wing.
Based on the original descriptions of the crash, I assumed the engine fell off.
From the photos, it’s clear it went up over the wing and impacted the fuselage with a (at least) minor explosion, which would have thrown foreign objects into the third engine in the tail for sure.
Losing 2/3 of the engines isn’t survivable on takeoff for this class of plane, at the weights they were at.
> I assumed the engine fell off
It's an engine - the thing pushing the entire plane forwards. Provided it is running (and at takeoff that's definitely the case), an engine being liberated from its plane suddenly has a lot less mass holding it back, so the logical thing to do is to shoot forwards. And because the wing is attached to the upper side of the engine, anything short of an immediate failure of all mounting points is probably also going to give it an upwards trajectory.
Add in air resistance, and you get the "swing across the wing and back" seen in the photos.
3 replies →
Adding summary analysis from AVHerald [0]
[0] https://avherald.com/h?article=52f5748f&opt=0
"Your IP address 104.28.103.15 has been used for unauthorized accesses and is therefore blocked! Your IP address belongs to Cloudflare and is being used by many users, some of which are hackers and hide behind the cloud/proxy to avoid being tracked down. Hence the automatic defense closed access from that IP address.
"Make sure to not use a proxy/cloud service for visiting AVH (e.g. Apple Users turn off your private relay) but your native IP address, then access should be possible without a problem again."
No thank you, AV Herald.
That's a pretty nice message. Most sites that filter VPNs and proxies just kill the connection, give a generic error, or subject you to endless captchas.
4 replies →
> On the aft lug, on both the inboard and outboard fracture surfaces, a fatigue crack was observed where the aft lug bore met the aft lug forward face. For the forward lug's inboard fracture surface, fatigue cracks were observed along the lug bore. For the forward lug's outboard fracture surface, the fracture consisted entirely of overstress with no indications of fatigue cracking
If I'm parsing this correctly, they're saying that fatigue cracks should have been visible in the aft pylon mount, and that the forward mount was similarly fatigued but showed no damage on the outside?
> If I'm parsing this correctly, they're saying that fatigue cracks should have been visible in the aft pylon mount, and that the forward mount was similarly fatigued but showed no damage on the outside?
If you can get to the report, Figure 7 shows the left pylon, with the forward and aft lug enlarged in the inset. Both lugs cracked on two sides. They're saying both cracks on the aft lug as well as the inboard crack on the forward lug were observed to be fatigue cracks, but the forward lug outboard fracture was observed to be entirely a stress crack.
Outboard and inboard are just away from and towards the center of the plane. On the left pylon, that's left and right, respectively. So, it looks like the left side crack in the forward lug developed from overstress, but the other three cracks were from fatigue. My expectation is that fatigue should be apparent upon the right kind of inspection, if timely, even if the metal has yet to fracture.
It sounds like the aft lug failed first, and then the not quite as compromised forward lug failed in overload.
Very fast. Quite sad to see it happen. Also quite puzzling is how the Air India disaster still does not have a root cause analysis done (though supposedly it will be released end of this year)
> Also quite puzzling is how the Air India disaster still does not have a root cause analysis done
Nothing puzzling. Straight-up cover-up.
Now, the interesting part would be to know what is being covered-up. Pilot error? Pilot suicide? Or a critical system malfunction Boeing cannot afford?
> quite puzzling is how the Air India disaster still does not have a root cause analysis done
Not that puzzling: the most likely explanation is pilot suicide and the Indian government does not want to acknowledge that.
The Indian authorities has blamed the pilots in every single crash. AND there is not enough evidence to guarantee that was the case. It is one of many possibilities.
Appreciate the transparency in these reports. The technical breakdowns always highlight how complex aviation safety is.
Link doesn't seem to be available now:
> Page not found
> The page you're looking for doesn't exist.
I found a link to the PDF that seems to work https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/G...
Also in case that link stops working I got it from this page https://www.ntsb.gov/investigations/Pages/DCA26MA024.aspx
EDIT: nevermind immediately after posting this comment it is now giving a 403 error
Your first link is working fine
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If anyone saved a copy locally, it'd be great if you could share it somewhere. (I, for once, did not, and the tab is gone now :-/ ).
Revised URL -https://www.ntsb.gov/investigations/Documents/DCA26MA024%20P...
Link to page that links to the report, as of now: https://www.ntsb.gov/investigations/Pages/DCA26MA024.aspx
surprised to see typos in aviation terms and acronyms: ADS-8 (page 3) and 747-BF (page 5)
Swapping B and 8 in both cases, which is typically something that happens with OCR. Weird.
Reminds me of xerox scanner fun, maybe someone scanned it to pdf to publicise?
Nontheless the pdfs have been replaced and the newer ones don't seem contain these errors anymore.
With many eyes, all typos are embarrassing.
The new document is an image.
pretty weird...
These all seem like OCR errors...? Why would there be OCR in this workflow? Did they print this out and then generate a PDF from a scan instead of the original source? To maintain an air gap maybe?
4 replies →
TIL about this eerily similar DC-10 crash in 2011:
Shortly after liftoff, 20 feet (6.1 m) above and 7,000 feet (2,100 m) down the runway, the No. 2 engine separated from the wing and struck the No. 1 engine's inlet cowling, causing it to produce drag and reduced thrust. Even with full right aileron and rudder, the plane started to descend and drift to the left. The captain lowered the nose and leveled the wings, which was followed by the plane making multiple contacts with the runway. After touchdown, the plane drifted left and departed the runway, crossing a taxiway before coming to rest in a saltwater marsh. A fire erupted which consumed the top of the cabin and the cockpit. All three crew members survived.
https://en.wikipedia.org/wiki/Omega_Aerial_Refueling_Service...
Obviously the DC-10 is not the MD-11, but the MD-11 is a direct descendant, including the trijet configuration.
The article you linked is talking about a 707, not a trijet. In particular, engine 2 on the MD-11 is the tail engine, not a wing engine.
...is this a bot comment? The accident you linked is very clearly of a Boeing 707, which has zero relation to a DC-10 and is most decidedly not a trijet.
A commenter in HN thread covering the initial crash mentioned that the left engine detaching might have been the cause https://news.ycombinator.com/item?id=45821537
The referenced AA Flight 191 is shockingly similar. It makes me wonder if aviation really is back sliding into a dangerous place.
40 years between severe accidents is fine in terms of expected failures. It's also not a good comparison because in the 70s maintenance crew were using a forklift to remive engines, improperly stressing the engine pylon. This was done as a shortcut
I don't know if it's "sliding back" as much as it is that this plane is also fundamentally from the 1970s.
The MD-11 was developed after that crash. Shouldn't its design and maintenance procedures have been informed by the incident?
7 replies →
Are you referring to AA 191 in 1979? That seems like low enough frequency event to not be worried about it.
The murder suicides in the last few decades seem more concerning.
Rather the opposite: if the cause is similar to AA 191, why weren't the actions taken after AA 191 to prevent a repeat effective? If we can get a repeat of that incident, what's preventing the industry from repeating the mistakes from all those other incidents from the past decades? Why aren't they learning from their past mistakes - often paid for in blood?
2 replies →
> The referenced AA Flight 191 is shockingly similar. It makes me wonder if aviation really is back sliding into a dangerous place.
I think it's cut throat capitalism at its best. Surely it was much too safe before, let's see how far back we can scale maintenance on the operations front but also how far back can you scale cost during development and production and then see where it takes us. If that changes the risk for population from 0.005 to 0.010, the shareholders won't care and it's great for profits.
I think we can see both but especially the latter with Boeing.
The entire MD-11 project was a budget-limited rush-job to try to capture some market share before the A340 and 777 came into service.
It produced an aircraft that failed to meet its performance targets, was a brute to fly and was obsolete the moment its rivals flew.
Douglas* by the early 1990s was a basket-case of warmed-over 1960s designs without the managerial courage to launch the clean-sheet project they needed to survive.
* as a division of MDC
I was under the impression that a plane could deal with an engine failure at any point in flight - including during takeoff.
Dropping an engine entirely is a similar situation to a failure - with the benefit that you now have a substantially lighter if imbalanced aircraft.
Should this plane have been able to fly by design even with an engine fallen off?
El Al 1862 was another flight [1] that had an engine fall off, taking another engine out with it. The pilots managed to fly around for a few minutes and attempt a landing, but there was too much structural damage.
It doesn't seem aircraft are designed to survive these types of catastrophic failures.
[1] - https://en.wikipedia.org/wiki/El_Al_Flight_1862
They seem to have lost the tail engine too. Yes, it is a significant problem that engine failures aren't independent, so trijets are kind of a bad design.
Not only did it happen at the worst possible moment, it took out a second engine on it's way out and over the plane. Two engines should've been enough to get off the ground and potentially land the plane, but one engine on a trijet isn't enough.
It nuked the tail engine so actually TWO engines failed.
From the wing down I assumed it may have depended if the engine coming out unintentionally means redundant hydraulic lines and mounts are also getting disconnected causing a complete loss of control not that it would have helped much at that point beyond minimizing ground damages.
Yes, but when the engine came off, it also disrupted the third engine in the tail. Can't take off in this model with 2 out of 3 engines gone.
Yeah, pilots I know saw puffs of flame coming out of the engine, and said that that's a tell-tale sign of a compressor stall. Which could have been caused by debris from the separating left engine striking the turbine.
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Even if they had the thrust (doubtful) there wouldn't be enough lift with a gaping hole in the leading edge of one wing.
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It didn’t fall off, it flew up and then landed back on the plane.
https://www.reddit.com/r/aviation/comments/1p276xx/ntsb_issu...
And also ripped open a giant hole in the fuel tank which allowed all of the fuel to be released and ignited.
This engine didn’t just fail, it failed catastrophically and took out another engine with it.
I'm surprised at how many years the plane went without having that part inspected. It looks like the failure was due to fatigue cracks, but the last time the part was inspected was in 2001?
I believe the part was at least visually inspected in 2021:
> A review of the inspection tasks for the left pylon aft mount found both a general visual inspection (GVI) and a detailed visual inspection of the left pylon aft mount, required by UPS's maintenance program at a 72-month interval, was last accomplished on October 28, 2021.
I’m seeing 2021 on page 10 - an I missing something?
The surveillance video mentioned in page 2 -- from which the series of still images are shown -- is that available publicly?
I haven't seen that one, this video [1] includes a different angle taken from a vehicle on the airport.
[1] https://youtu.be/POKJUJk_2xs?t=342
Not an aviation expert, nor I want to be one, but the images look pretty intense.
It is incredible to me how quickly some lives can go from "another day as usual" to "gone" in a matter of seconds.
As I told my friends, this preliminary report annoys me. It annoys me for the same reason it seemingly annoys the NTSB: American 191 is nearly identical on the surface, right down to the engine detachment and resultant loss of the aircraft, in almost the exact same spot on the airframe, ~45 years later.
Needless to say they’re going to be scrutinizing everything to determine what the cause is and the sequence of events that created the accident, but I also suspect everyone involved is just as annoyed at this as I am, given that this exact situation should have been fixed already.
* Annoyed = seething rage
That's terrible. If the NTSB had flagged this flaw before then someone failed with an inspection regime or maintenance.
The NTSB doesn't ever accept the "sometimes bad things happen, shrug" excuse and kudos to the professionals there.
It's just time to kill the MD-11 entirely. These 3-engine aircraft are too risky to continue flying.
McDonnell-Douglass right there that's where the problems start.
Gyroscopic precession took the left engine to the right. In AA 191 the right engine departing to the right did not affect the center engine. Sadly the engine failure procedure at the time mandated slowing down to V2 which was below the stall speed with slats retracted. There's now revised procedure and hydraulic fuses.
I expect all remaining aircraft will be getting new rear pylon lugs with shortened inspection intervals - provided the replacement cost is below the value of continued usage.