Posted on 02/28/2023 8:42:22 AM PST by Paal Gulli
First reported here (twice), complete with video, when it happened last December at NAS JRB Fort Worth. The mishap was remarkable because the pilot ejected while the a/c was on the ground.
The news reports that followed all spoke to the engine as the cause -- which would seem to indicate that neither the pilot nor other aspects of the aircraft were under suspicion -- and DoD ordered engine manufacturer Pratt & Whitney to stop delivering new engines for the F-35B until the problem was sorted.
Last Friday, a news source that may not be quoted here for copyright reasons reported that P&W had identified the cause of the mishap as "a rare system phenomenon involving harmonic resonance" (in the engine). Not stated directly but P&W must have told DoD the problem is fixed because they have approved resuming engine deliveries. However, for reasons the story does not address (possibly waiting on a retrofit of "the fix" to all F-35Bs already in the field), the a/c are still grounded, which means the Marines won't be getting any new F-35Bs for the timebeing.
Actually, that's exactly why I posted this. The "incriminating" news story already had been posted, and I'm sure a great many in the Freepr peanut gallery rushed to the conclusion that it was pilot error. As often happens, people are in a rush post "bad news" stories but then ignore the follow-ups, which often are more important that the original story.
To this point, there is no indication the pilot did anything apart earning his pay.
New to me. Fascinating.
Is that anything like “sinusoidal repleneration”?
The turbo-encabulator never had that problem.
https://www.youtube.com/watch?v=Ac7G7xOG2Ag&t=6s
Except that wasn't what happened. It wasn't anywhere near an excessive rate of descent, especially not for an airframe meant to be slammed onto a carrier deck with impunity. I've seen Cessna 150s with a soloing student pilot at the controls pranged on harder than that, and nothing broke.
All objects will tend to rotate about their center of gravity. The CG of most airplanes is somewhere over the main wing. When the thrust from the front duct failed, and with the aft duct still working normally, the dissymmetry of thrust caused the empenage to pitch up, the airframe to rotate about its CG, and the nose to be driven down and into the tarmac.
The nose gear broke because the nose pitched down abruptly and struck the ground while the main gear were not on the ground. The nose gear wasn't designed to support the full weight of the airplane at such an unusual angle, and it failed.
It all started with inadequate or uncontrolled thrust coming from the forward duct. Nothing the pilot could do to cause or correct it.
That’s a MIL-STD-12 approved abbreviation.
Also why I type “pix” instead of “pic” e.g., in many of these threads.
Ok, have a look at the video again; he’s descending hot (I have landed a Harrier a few times) and lands on all three gears, level. Then he bounces up, tilts forward, and hits his front landing gear, while rolling to the left. He slams down again, level, and then ejects. His engine is still running - so unless his throttle was jammed, he didn’t try to close the throttle before leaving.
P.S: if I had student slam a 150 like that, he’d be done.
I looked at the video again and I stand corrected: that rate of descent wasn’t that bad - but after his touchdown, he went up again and then rotated forward and the nose dropped and he stuck. The puzzling part for me is why he bounced up again and when it started going south, why he didn’t chop the throttle and let the plane settle down.
Reminds of a car accident I saw once where a lady ran off the freeway into a grove of trees and kept blasting around in circles, round and round those trees, her foot still on full throttle.
What does STD stand for? : )
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