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NTSB Preliminary Report – UPS Boeing MD-11F Crash [pdf]
- frenchman_in_ny 11mo agoAdding summary analysis from AVHerald [0] [0] https://avherald.com/h?article=52f5748f&opt=0 https://avherald.com/h?article=52f5748f&opt=0
- tremon 11mo ago> 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?
- pfdietz 11mo agoIt sounds like the aft lug failed first, and then the not quite as compromised forward lug failed in overload.
- toast0 11mo ago> 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.
- the-grump 11mo ago"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.
- kube-system 11mo agoThat'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.
- ErroneousBosh 11mo agoI block all traffic from Cloudflare outright on my servers. Every so often they sneak in new blocks of IP addresses though so you're playing whack-a-mole with a particularly scummy opponent.
- trollbridge 11mo agoThey're pretty upfront about their ranges: https://www.cloudflare.com/en-au/ips/ https://www.cloudflare.com/en-au/ips/ Or if you prefer: https://www.cloudflare.com/ips-v4/# https://www.cloudflare.com/ips-v4/#
- worewood 11mo agoThey could've blocked just the comments, allowing at least read-only access to the site, instead of blocking it off entirely
- kube-system 11mo agoSo could everyone that blocks network traffic for various reasons, but usually they don't because they're not doing it in the primary application layer, but using a WAF or reverse proxy or something else in front of their application... and also most DGAF to cater specifically to the users they block. Again, you're usually lucky to even get a return packet.
- Aman_Kalwar 11mo agoAppreciate the transparency in these reports. The technical breakdowns always highlight how complex aviation safety is.
- philip1209 11mo agoOriginally 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.
- testplzignore 11mo agoMaybe stupid question: Why not have the #1 engine spin in the opposite direction so that it doesn't go towards the fuselage?
- captaincrowbar 11mo agoBecause making every jet engine in two different models would make them a lot more expensive. It would also cause maintenance issues because of non-interchangeable parts.
- cj 11mo agoThere might be some truth in that. But the report doesn't confirm that theory.
- philip1209 11mo agoI'm presenting it "useful not true" - not an RCA.
- rconti 11mo agoWhat 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.
- cj 11mo agoThat the engine was flung into the fuselage due to gyroscopic forces.
- albert_e 11mo agoThe surveillance video mentioned in page 2 -- from which the series of still images are shown -- is that available publicly?
- rft 11mo agoI 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 https://youtu.be/POKJUJk_2xs?t=342
- sosodev 11mo agoA 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 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.
- lotsofpulp 11mo agoAre 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.
- deleted 11mo ago[deleted]
- crote 11mo agoRather 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?
- lotsofpulp 11mo agoI understood the post I responded to to be referring to the cause as the engine detaching from the same type of plane, not the root cause for why the engine detached. Per the “investigation section” in the wikipedia article, I would be surprised if it was the same root cause: https://en.wikipedia.org/wiki/American_Airlines_Flight_191 https://en.wikipedia.org/wiki/American_Airlines_Flight_191 I assume the erroneous maintenance procedures that led to the loss of AA191 were rectified a long time ago.
- mrguyorama 11mo ago>rectified a long time ago. There's no such thing as "This is fixed forever". If lax maintenance oversight has led to companies re-introducing known dangerous maintenance procedures or departing from known good ones, then we will be back in the 70s in terms of airplane safety and people will have to die again to relearn those lessons. Someone's always trying to claw you in the less safe direction. It's a constant battle to not regress. But IDK, hopefully this plane just got some sort of "unlucky" about fatigue somehow, and it doesn't have far reaching consequences.
- londons_explore 11mo agoI 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?
- lotsofpulp 11mo agoIt didn’t fall off, it flew up and then landed back on the plane. https://www.reddit.com/r/aviation/comments/1p276xx/ntsb_issues_the_preliminary_report_for_its/?utm_source=share&utm_medium=mweb3x&utm_name=mweb3xcss&utm_term=1&utm_content=share_button https://www.reddit.com/r/aviation/comments/1p276xx/ntsb_issu...
- buildsjets 11mo agoAnd also ripped open a giant hole in the fuel tank which allowed all of the fuel to be released and ignited.
- baggy_trough 11mo agoYes, 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.
- jeffbee 11mo agoEven if they had the thrust (doubtful) there wouldn't be enough lift with a gaping hole in the leading edge of one wing.
- sq_ 11mo agoYeah, if they had had more altitude, I would guess that this would have looked even more like the AA 191 crash from 1979, with the left wing stalling and causing a roll and pitch down. That in turn reminds me of the DHL flight out of Baghdad in 2003 that was hit by a missile [0]. Absolutely amazing that they managed to keep it together and land with damage like that. [0] https://en.wikipedia.org/wiki/2003_Baghdad_DHL_attempted_shootdown_incident https://en.wikipedia.org/wiki/2003_Baghdad_DHL_attempted_sho...
- chimpontherun 11mo agosurprised to see typos in aviation terms and acronyms: ADS-8 (page 3) and 747-BF (page 5)
- ynniv 11mo agopretty weird... NATIONAL TRANSPORTATION SAFEN'BOAFID :J11...:i= of ArutiOn SMel@LA5 301 A.,r Tral1C.IYU';UQlt-Ort!! NTS,B ri@ss @at.Joo JurtJer DCA26 22\C2<
- maxbond 11mo agoThese 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?
- ynniv 11mo agoit would seem so. so the question is why they would maintain an air gap for a safety report
- deleted 11mo ago[deleted]
- Denvercoder9 11mo agoSwapping B and 8 in both cases, which is typically something that happens with OCR. Weird.
- rft 11mo agoGrounding 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.
- SteveNuts 11mo agoEven 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!
- mandevil 11mo agoI 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.
- joleyj 11mo agoThe airforce retired the KC-10 in 2021.
- buildsjets 11mo agoThe KC-10 went out of service last year. None are operating.
- dzonga 11mo agoMcDonnell-Douglass right there that's where the problems start.
- GiorgioG 11mo agoIt's just time to kill the MD-11 entirely. These 3-engine aircraft are too risky to continue flying.
- LinuxAmbulance 11mo agoI'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?
- LPisGood 11mo agoI’m seeing 2021 on page 10 - an I missing something?
- deleted 11mo ago[deleted]
- loeg 11mo agoI 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.
- serhack_ 11mo agoNot an aviation expert, nor I want to be one, but the images look pretty intense.
- pseudosavant 11mo agoIt is incredible to me how quickly some lives can go from "another day as usual" to "gone" in a matter of seconds.
- kurtoid 11mo agoLink doesn't seem to be available now: > Page not found > The page you're looking for doesn't exist.
- zorgmonkey 11mo agoI found a link to the PDF that seems to work https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/201958/pdf 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 https://www.ntsb.gov/investigations/Pages/DCA26MA024.aspx EDIT: nevermind immediately after posting this comment it is now giving a 403 error
- greenavocado 11mo agoYour first link is working fine
- zorgmonkey 11mo agoYeah working again for me too, they're probably having some sort of server problems
- deleted 11mo ago[deleted]
- AceyMan 11mo agoIf 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 :-/ ).
- haeberli 11mo agoLink to page that links to the report, as of now: https://www.ntsb.gov/investigations/Pages/DCA26MA024.aspx https://www.ntsb.gov/investigations/Pages/DCA26MA024.aspx
- waiwai933 11mo agoLooks like it's been moved to https://www.ntsb.gov/investigations/Documents/DCA26MA024%20Preliminary%20Report.pdf https://www.ntsb.gov/investigations/Documents/DCA26MA024%20P...
- deleted 11mo ago[deleted]
- Aloha 11mo agoRevised URL -https://www.ntsb.gov/investigations/Documents/DCA26MA024%20Preliminary%20Report.pdf https://www.ntsb.gov/investigations/Documents/DCA26MA024%20P...
- decimalenough 11mo agoTIL 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_Services_Flight_70 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.
- filleduchaos 11mo ago...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.
- loeg 11mo agoThe 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.
- stego-tech 11mo agoAs 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
- filleduchaos 11mo agoActually, the two accidents are only superficially similar, and there is no basis for saying that "this exact situation" should have already been fixed. And no, this is not just pedantry. A bulkhead fracturing from impact damage and its mounting point failing from fatigue cracking are nowhere near the same thing, even if they might lead to the same outcome.
- stego-tech 11mo agoI’m not sure where you’re getting these conclusions from, because AA191 was an issue where the engine separated from the wing and took hydraulics with it, creating a sequence of failures that resulted in the loss of the airframe. The UPS flight also had a separation of the engine from the wing and created some sequence of events that resulted in the loss of the airframe, but they’ve made it very clear in the report that the how and the why are still very much open questions. My point - and from what I see in the report, a grievance shared by the NTSB, given their citation of AA191 - is that both aircraft come from the same lineage (DC-10/MD-11), the same manufacturer (McDonnell-Douglas, now Boeing), had the same failure (engine separating from wing assembly during takeoff roll), and with all involved parties throwing up their hands and swearing they followed all the rules and maintenance schedules. And that’s too many coincidences to just dismiss outright from the get-go.
- filleduchaos 11mo ago
- BXLE_1-1-BitIs1 11mo agoGyroscopic 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.
- Simon_O_Rourke 11mo agoThat'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.
- anshumankmr 11mo agoVery 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)
- objclxt 11mo ago> 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.
- anshumankmr 11mo agoThe 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.
- fransje26 11mo ago> 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?
- johnnienaked 11mo agoIt's so similar to AA191