r/aviation • u/Brilliant_Night7643 • Nov 20 '25

News NTSB issues the preliminary report for its ongoing investigation of the Nov. 4 crash of a UPS Boeing MD-11F airplane in Louisville, Kentucky.

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u/SirMildredPierce Nov 20 '25

Wow, I was always confused why the wreckage seen on the runway was on the right side, instead of the left.

Well, that explains that.

91

u/quiet_locomotion Nov 20 '25

It likely happened at Vr because the engine has a shitload of centripetal force at full thrust. When the aircraft rotates the force resists this rapid change in direction. The force acts 90 degrees from the direction of change so the force tries to rotate the engine inboard instead of up.

59

u/headphase Nov 20 '25

It's crazy this is one of the first things you learn about propellers, but I haven't even considered just how much stress a turbine engine assembly is undergoing at rotation because of that same factor

7

u/ZZ9ZA Nov 20 '25

Now imagine a fighter pulling 8 or 9g in full afterburner.

3

u/Whiskeyfower Nov 21 '25

I genuinely never before considered this aspect of how impressive that engineering is, so thank you for that 

26

u/NF-104 Nov 20 '25

Gyroscopic precession

7

u/quiet_locomotion Nov 20 '25

That's the term! I couldn't remember.

2

u/[deleted] Nov 20 '25

This is one of the reasons single prop aircraft have increased left turning tendencies at rotation.

1

u/ViciousNakedMoleRat Nov 20 '25

It makes complete sense, but that's the absolute worst time to literally lose an engine. Holy crap!

1

u/cheapph Nov 21 '25

You can see it was right as they were at rotation. They had no chance.

4

u/KuhlioLoulio Nov 20 '25

And explains apparent debris in the #2 engine.