UPS MD-11 crash at SDF

MikeD said:
If anything, #2 appears to be compressor stalling from possibly the flame ingestion, if not FOD ingestion. In the KC-10 series, there’s about 15+ feet or so of distance from the inlet lip of the #2 intake to the front end of the actual engine itself, so any disturbed air entering the inlet that could potentially cause compressor stalling, generally straightens out by the time it reaches the actual engine. But I can’t imagine that this amount of disturbed air, likely laced with FOD from the departed engine, didn’t do some degree of interruption at best, or damage at worst, that there wasn’t some degree of thrust loss at this critical phase of flight. Interestingly, the #2 engine is normally the least susceptible to compressor stalls, just due to its inlet design, but the most susceptible to FOD due to its location, on these jets.
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Agree with the above. They flew the fleet three days post accident until they were grounded by the FAA over the weekend. The seperated engine was sitting on the runway and the "airport surveillance video" would have been immediately available, I would think. Mike, do you think the video could have been withheld from the company due to it being part of an FAA investigation?
 
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MikeD said:
And “so fast”, wasn’t fast enough, like I inquired about in the first pages of this thread. UPS should’ve been concerned enough to not keep their MD planes flying for days (and perhaps longer), when they had a separated engine sitting in the infield grass, far before the wreckage of their plane off the departure end of the runway, all right there at their home base. Should’ve been enough concern for the unknown to at least temporarily not fly them, until the Boeing decision did it for them.
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Not only that, looking at the pictures of the fractures of the pylon mount, it would have been obvious that there was a significant issue and would have been noted by the most junior A&P out there...in an instant.
 
HeyEng said:
Not only that, looking at the pictures of the fractures of the pylon mount, it would have been obvious that there was a significant issue and would have been noted by the most junior A&P out there...in an instant.
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The plane came out of C check just a couple weeks before the accident. UPS used a vendor for this.
 
DE727UPS said:
Agree with the above. They flew the fleet three days post accident until they were grounded by the FAA over the weekend. The seperated engine was sitting on the runway and the "airport surveillance video" would have been immediately available, I would think. Mike, do you think the video could have been withheld from the company due to it being part of an FAA investigation?
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Video from all sources would’ve been requested and collected, and of course would need to be reviewed to find what they showed, and likely UPS never saw or reviewed the video before turning it over by request. But even with that, the physical evidence sitting at the scene should’ve made UPS managements concern raise to an alarming level, if not the NTSBs, to take at least a temporary company action, regardless of what anyone else did, before Boeing had to do it for them. Just my opinion.
 
Brian29 said:
Wow. It appears number 1 departed post rotation.
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I'd think from an engineering/physics standpoint, it makes some sense that it would have happened then. Rotation imparts a force on the airframe/engines/pylons, which could have been the final straw for whatever failed in the engine pylon attachment hardware. Hardware that would already be under heavy loads even in a normal situation, trying to restrain a motor at high thrust from ripping itself off the wing. From there, it's just the physics of an underwing engine at a high power setting, that now has a rotational moment applied (due to the pylon likely not failing symmetrically/immediately) to its thrust vector. At least that would be my armchair analysis. Horrifying images for sure.
 
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HeyEng said:
I think even if #2 wasn't FOD'd out (or compressor stalled), the fate of that airplane was sealed. It wasn't going to fly anymore. :(
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Theoretically, it would’ve had the climb performance if only the complete loss of #1 was encountered and the other two engines were unaffected. Whether or not there was other damage to the wing, to lift components of the wing, or otherwise, remains to be seen and would obviously be a factor. But as others have mentioned here who fly the plane, loss of the #1 engine, plus any performance degradation of any other engine, and yes in this phase of flight at these weights, fate would be sealed even with no other damage. Sadly.
 
HeyEng said:
I think even if #2 wasn't FOD'd out (or compressor stalled), the fate of that airplane was sealed. It wasn't going to fly anymore. :(
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Actually, that's the whole question: If #2 was operating normally, I think the aircraft would be flyable. In fact, you could argue that they did fly it. We have an engine "...separation" checklist on my fleet. The engine is near enough to the CG that while there would be a CG shift, I'd guess it's still controllable. On the other hand, you aren't climbing with a dual engine failure.
 
I’m surprised this video angle wasn’t leaked by some airport employee (as was the case for the DCA midair).

Kudos to them, I agree in principle, but it feels like if they had released this video immediately, the 3 airlines here would have grounded the MD11 immediately too. Instead of the 3-4 day wait.
 
On AA191 after the engine & pylon separated, the outboard slats retracted, causing the wing to stall and aircraft to roll. As @MikeD said, climb performance remains if only #1 is lost, so something else caused the loss of power and left roll.
 
MikeD said:
Theoretically, it would’ve had the climb performance if only the complete loss of #1 was encountered and the other two engines were unaffected. Whether or not there was other damage to the wing, to lift components of the wing, or otherwise, remains to be seen and would obviously be a factor. But as others have mentioned here who fly the plane, loss of the #1 engine, plus any performance degradation of any other engine, and yes in this phase of flight at these weights, fate would be sealed even with no other damage. Sadly.
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Hammertime said:
Actually, that's the whole question: If #2 was operating normally, I think the aircraft would be flyable. In fact, you could argue that they did fly it. We have an engine "...separation" checklist on my fleet. The engine is near enough to the CG that while there would be a CG shift, I'd guess it's still controllable. On the other hand, you aren't climbing with a dual engine failure.
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Um, are we not seeing the wing on fire, post engine separation in picture #4? What happened to the other 2 engines would be moot if the wing is on fire, right?
 
Cherokee_Cruiser said:
Um, are we not seeing the wing on fire, post engine separation in picture #4? What happened to the other 2 engines would be moot if the wing is on fire, right?
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It depends what the damage is at the time and what is on fire. Could be separated fluid lines, etc. One of the questions for investigators will be, aerodynamically, was the plane flyable at that moment of liftoff, damage wise? Damage from engine separation, damage from fire, etc. it’s going to be an interesting forensic analysis by the structure team. Of course, the fire could’ve been not enough to prevent the plane from lifting off and initially flying, but could’ve been enough to cause catastrophic damage later (or earlier) on climbout resulting in loss of control or explosion etc. Any number of factors that will have to be pieced together.

Investigation-wise, I’m not sure how much useable pieces of wreckage there are to investigate, just with the horrendous amount of fire damage from post-impact due to the amount of fuel onboard. It will be very difficult to determine, from main wreckage parts, what might have been pre-impact fire or damage, and what will have been post-impact fire/damage, if any useable pieces from those airframe areas even remain.
 
I don’t understand why this report wouldn’t address what the number 2 engine was doing, and maybe even a little more information on the speed the aircraft attained. I can understand not putting the crew actions in a preliminary report. Every pilot however is asking those first two questions.
 
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MikeD said:
It depends what the damage is at the time and what is on fire. Could be separated fluid lines, etc. One of the questions for investigators will be, aerodynamically, was the plane flyable at that moment of liftoff, damage wise? Damage from engine separation, damage from fire, etc. it’s going to be an interesting forensic analysis by the structure team. Of course, the fire could’ve been not enough to prevent the plane from lifting off and initially flying, but could’ve been enough to cause catostrophic damage later on climbout resulting in loss of control or explosion etc. Any number of factors that will have to be pieced together.

Investigation-wise, I’m not sure how much useable pieces of wreckage there are to investigate, just with the horrendous amount of fire damage from post-impact due to the amount of fuel onboard. It will be very difficult to determine, from main wreckage parts, what might have been pre-impact fire or damage, and what will have been post-impact fire/damage, if any useable pieces from those airframe areas even remain.
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That pic shows the fire continued “in the area of the left option attachment.”



I’m not aware of any commercial jetliner that took off, the wing caught fire, and the plane safely landed back. Are there any examples? I would assume a wing on fire, especially near a pylon area with fuel lines, is basically a doomed situation.

Prelim report link:

 
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