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NTSB Finds Cause of Mooney Structural Failure Crash

Posted: Mon Mar 27, 2023 4:37 am
by Scudrunner

Re: NTSB Finds Cause of Mooney Structural Failure Crash

Posted: Mon Mar 27, 2023 4:47 am
by Slick Goodlin
That photo is wild.. I was hoping the article would explain some of the physics of how it got to that point.

Re: NTSB Finds Cause of Mooney Structural Failure Crash

Posted: Mon Mar 27, 2023 11:36 am
by Nark
Slick Goodlin wrote:
Mon Mar 27, 2023 4:47 am
That photo is wild.. I was hoping the article would explain some of the physics of how it got to that point.
It did, at least on a basic level: 8g’s in a spiral dive.

I think the article was written because of the doorbell camera pic. What I gathered was typical graveyard spiral on approach.
I may seem callous, but kind of a dime a dozen.

Proficiency vs currency …

Re: NTSB Finds Cause of Mooney Structural Failure Crash

Posted: Mon Mar 27, 2023 12:25 pm
by Colonel
Assuming that their calculation of +8G is correct….

Remember this is a spiral dive, NOT a straight pull. See Aerodynamics For Naval Aviators which explains that with a torsional load, the G must be decreased to 2/3 of the corresponding design or ultimate load.

This is not academic for those of us that fly snap rolls and must know our safe entry speed to observe design limit G.

Anyways a +8G torsional load corresponds to a +12G straight pull which sounds about right for a Mooney ultimate load. Strong airplane.

PS if it helps, they were not conscious at impact. The set of civilian pilots who can stay awake at a sustained +8G (eg L39) is minuscule.

Re: NTSB Finds Cause of Mooney Structural Failure Crash

Posted: Mon Mar 27, 2023 3:59 pm
by Slick Goodlin
What was making those Gs though? If it was a pull you’d think the stabilizers would fold down. Also somewhat incredible that both wings folded up and not just one, plus they stayed attached.

Re: NTSB Finds Cause of Mooney Structural Failure Crash

Posted: Tue Mar 28, 2023 1:47 pm
by Colonel
I remember doing the interior on our M20J and looking at the center spar section. It looked like a bridge truss - massively over-engineered.

Then compare it to an RV which looks like tinfoil in comparison.

Re: NTSB Finds Cause of Mooney Structural Failure Crash

Posted: Tue Mar 28, 2023 8:46 pm
by Squaretail
Colonel wrote:
Tue Mar 28, 2023 1:47 pm
It looked like a bridge truss - massively over-engineered.

Then compare it to an RV which looks like tinfoil in comparison.
One of the reasons I'm not a super fan of most home builts. Guys think they're as tough as factory built planes, and they're just not.

Re: NTSB Finds Cause of Mooney Structural Failure Crash

Posted: Tue Mar 28, 2023 10:26 pm
by Colonel
This is a bit of a digression but ….

I find Beechcraft distressing. They have this wonderfully solid feel , but all their spars and center sections suffer from cracking.

Image

Not cool.

Re: NTSB Finds Cause of Mooney Structural Failure Crash

Posted: Wed Mar 29, 2023 12:45 am
by Nark
Add in. $5-7 k spar X-ray every 5ish years.


I should have invested in bitcoin and boats…