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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
by rft 10mo ago
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.
- SteveNuts 10mo 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 10mo 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 10mo agoThe airforce retired the KC-10 in 2021.
- buildsjets 10mo agoThe KC-10 went out of service last year. None are operating.
- loeg 10mo agoYeah, but DC-10 based tankers for wildfire fighting were still flying until the recent grounding: https://en.wikipedia.org/wiki/DC-10_Air_Tanker https://en.wikipedia.org/wiki/DC-10_Air_Tanker (Blancolirio points out that the DC-10 tanker is what they modernized to relatively recently -- before that they were flying even more dangerous WW2 airframes for firefighting.)
- mandevil 10mo agoDamnit, I knew that! Just forgot it in the moment.
- inferiorhuman 10mo agoMost of the DC-10s in service in the US are used for fire fighting.
- dingaling 10mo agoAnd with Omega Air, for contracted air refuelling https://www.omegaairrefueling.com/ https://www.omegaairrefueling.com/
- mandevil 10mo agoYes, but there are many MD-11's still flying as freighters. There are four fire-fighting DC10's out of ~8 still flying, but there are 25 Mad Dogs (MD-11) at UPS, 38 with FedEx, and Western Global has 4, so there are plenty of MD-11F's around.
- dreamcompiler 10mo agoHere are 4 of them. All grounded now. https://www.10tanker.com/gallery https://www.10tanker.com/gallery
- m2fkxy 10mo agoMad dogs are MD-80s.
- rft 10mo agoGiven 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.
- TinkersW 10mo agoOne other accident that was similiar, but these planes have had a ton of crashes for other reason.
- rft 10mo agoI managed to find some statistics on hull losses per million departures [1, p. 13]. Seems like indeed MD-11s have a highish rate of incidents by that metric compared to other types, even if they are not catastrophically less safe than other planes. That metric stacks the statistics a bit against cargo planes, which most (all?) MD-11s are now. These planes tend to fly longer haul instead of short hop, so you get more flight time/miles but less departures. There are also likely some other confounding factors like mostly night operations (visibility and crew fatigue) and the tendency to write off older planes instead of returning them to service after an incident. Plus these aircraft have been in operation long enough that improvements in procedures and training would impact them less than more modern types, as in they already had more accidents before these improvements. [1] https://www.boeing.com/content/dam/boeing/boeingdotcom/company/about_bca/pdf/statsum.pdf https://www.boeing.com/content/dam/boeing/boeingdotcom/compa...
- inferiorhuman 10mo agoThe DC-10 had a number of other problems, but the MD-11 has always had a reputation of being an unforgiving aircraft especially when compared to the DC-10. It's less about training and more that the MD-11 was simply too many design compromises piled on to an old design. The MD-11 had a pretty short service life as a passenger aircraft because it simply wasn't very fuel efficient compared to the competition, safety wasn't really the motivating factor. However fuel consumption was behind some of the poor design choices McDonnell/Boeing made. In broad strokes: McDonnell/Boeing shrunk the control surfaces to improve fuel consumption "necessitating" poorly designed software to mask the dodgy handling and higher landing speeds. This exacerbated a DC-10 design "quirk" where hard landings got out of hand very quickly and main landing gear failure would tend to flip the plane. Yeah you can train around this but when something else goes tits up you've got a lot less leeway to actually recover safely.
- loeg 10mo agoAirlines haven't been using them, or at least not 1st world airlines. Just freight and wilderness fire fighters.
- mrpippy 10mo agoUPS 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.
- deleted 10mo ago[deleted]
- virtue3 10mo agoMost 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.
- burnt-resistor 10mo agoThere were only about 18 aircraft of all types still flying at the time and none are dedicated passenger aircraft. Indefinite grounding is the most sensible move. Now, Boeing, et. al. are trying to evaluate the deficiencies in existing D checks and put together an inspection regime (i.e., NDT) that would proactively identify fatigue that would economically permit continued serviceable operation. If this feat turns out to be impossible for technical or cost reasons, then and only then will the grounding will become permanent.
- bunderbunder 10mo agoAnd 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.
- loeg 10mo agoYeah, 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?
- potato3732842 10mo ago> in which case, why have the tail engine at all? "you know what this motorized piece of anything needs, less power" -nobody, ever
- lazide 10mo agoBased 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.
- crote 10mo ago> 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.
- lazide 10mo agoSure, but if the engine grenades it can take it’s mounts with it and not shoot off like a bottle rocket in front of and over the plane, dropping down and under the plane instead (or even just sit there). Same with a compressor stall, or whatever. It’s clear from the photos this wasn’t the engine failing at all, and in fact the engine kept producing a ton of thrust (probably until it ran out of fuel as it pulled it’s fuel line apart while departing the wing), and instead the thing that is supposed to be so incredibly strong that it restrains all this chaos failed. Which is a pattern in this family of aircraft, but definitely not a common or normal thing in general eh? Most aircraft, the engine stays with the airframe even if it turns into a giant burning pile of shrapnel and dead hopes and dreams.
- inferiorhuman 10mo agoFully functioning engines departing from aircraft isn't common but it's not unheard of either. Off the top of my head it's happened a few times on the 747 and 737.
- cyberax 10mo ago> 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.
- PunchyHamster 10mo agoIt 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.
- decimalenough 10mo ago> 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.
- pixl97 10mo agoLosing cargo jet capacity right before the holidays may cause some issues.
- citbl 10mo agoAll cargo companies run a wide fleet of many different plane types, particularly to avoid this very problem of being grounded by the FAA. But yes, these were still widely used in cargo transports. Although newer 2 engine planes can haul the same kg and use a lot less fuel.
- sathackr 10mo agoCaptain 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 https://youtu.be/CmXLQHhUtv4?t=499