Minnesota Crash

[RLCarter]

1 hour ago, Ragsf15e said:

The centrifuge is one of the worst experiences ever.  You’ve never been so exhausted, dizzy or sick in your life.

Sure sounds like my 1st marriage 

[chrixxer]

On 8/18/2021 at 2:48 PM, David Lloyd said:

I saw a video either here or Beechtalk, a couple weeks back about the Saturn V and it was 1.25 at launch

I remember reading somewhere (but now of course can't find it) that Saturn V launches were, at least from the astronauts' perspective, very gentle. The first few seconds it was impossible for them to know (at least by feel) that they'd even left the ground.

Ah, found it:

“The Saturn V had a much lower thrust-to-weight ratio than Titan II GLV, the launch system used by Project Gemini, NASA's second human spaceflight program. Richard F. Gordon, Jr. described Saturn V as "an old man's ride", with "a lot more shake-rattle-and-roll" but milder thrust. Buzz Aldrin and other Apollo 11 astronauts agreed that unlike Titan, they could not tell when Saturn V liftoff occurred except from instruments.”

https://en.wikipedia.org/wiki/Saturn_V#Titan_II

[LANCECASPER]

10 hours ago, 1980Mooney said:

The person just posted on KathrynsReport and said that the damage to the entire tail occurred before the plane was sold new originally.  The damage occurred when it was still the property of Mooney Aircraft Corporation.  Hence it was hauled back to the factory.  It will not appear in the logs or in any report.

It better be in the logs

[LANCECASPER]

This post was from almost 4 years ago in a thread about Rockets, but seems to apply here:

[A64Pilot]

On 8/21/2021 at 12:22 AM, LANCECASPER said:

It better be in the logs

Well we have established log book data is only required to be kept for one year, 337’s are forever, no 337 is filled out under manufacturing, when a aircraft is in manufacturing, there is no logbook. Aircraft is under MIDO jurisdiction, but build records should indicate anything that happens, but they aren’t supplied to the purchaser, the Factory keeps them, we kept all of them so I don’t know how long they are required to be kept.

An aircraft isn’t “born” until the the DMIR which is Designated Manufacturers inspectors Representative, a manufacturers employee working as an FAA Representative completes a Conformity inspection and issues an Airworthiness Certificate, then it becomes an aircraft and is no longer being manufactured, but being maintained and as such is under FSDO and not MIDO. Those two don’t intermingle at all.

At this point the manufacturer can’t do anything to the aircraft unless they have a Repair Station. An individual A&P can, but the manufacturer can’t.     

‘All kinds of damage is dealt with during manufacturing and there is supposed to be paperwork to cover all of it, say a mis-drilled  hole for example, a form should be submitted for Engineering review and Engineering will determine what needs to be done to correct the fault. For smaller parts we just scrapped them as that was easier and cheaper.

Very often for something like a mis-drilled hole you will see a inspection stamp right beside of it so that the next person will know it’s been dealt with properly.

So if this aircraft was repaired prior to the DMIR and issuance of an airworthiness certificate then the paperwork for the repair would be in the build records, if after then most likely there would be a 337 and those are kept at Oklahoma City by the FAA forever, but as with everything done by the FAA it’s not perfect, many of my old 337’s for my 140 when the FAA went from paper to digital they scanned the 337’s and many are illegible and or blank.

[Scott Dennstaedt, PhD]

The NTSB preliminary report has been posted for this accident.  Read it here.  Not a lot of new information in the report, but some info on the debris field and examination of the wreckage that might be of interest.  

[jlunseth]

Thanks Scott. How sad.

[A64Pilot]

38 minutes ago, 1980Mooney said:

What condition/forces would rip the elevator from its hinge blocks located on the horizontal stabilizer (“The three outboard hinge blocks of the left elevator remained attached to the left horizontal stabilizer, with the rivets pulled out and sheared off the elevator”)? …Flutter induced by a high speed dive?

It could have been flutter, but my bet is a severe overload, remember the arse end has to be pushed down very hard to pull excessive positive G’s.

I think excessive turbulence / wind shear  has been sort of ruled out?

[Shadrach]

43 minutes ago, A64Pilot said:

It could have been flutter, but my bet is a severe overload, remember the arse end has to be pushed down very hard to pull excessive positive G’s.

I think excessive turbulence / wind shear  has been sort of ruled out?

Perhaps an abrupt pitch control reversal combined with high speed.

[A64Pilot]

27 minutes ago, Shadrach said:

Perhaps an abrupt pitch control reversal combined with high speed.

yeah a reversal would really put some bending loads on it

 

[LANCECASPER]

16 hours ago, Shadrach said:

Perhaps an abrupt pitch control reversal combined with high speed.

Maybe at high speed descent being told by ATC that he is way below course and then pulling back abruptly. One possiblity.

[hypertech]

Are the control rods really that strong?  I would have guessed that the pin holding the yoke would come off before a control input could break the wings.

[EricJ]

4 hours ago, 1980Mooney said:

Remember that the rear passenger was sitting directly on top of that portion of the center section of the main spar as it broke and fragmented - it must have been horrific.

I suspect the tail failure caused an abrupt pitch-up which induced enough g-force to fail the spars.   That amount of force would also likely have g-loc'ed all of the occupants, so the only horror was probably the few moments that led to the tail failure.

[aviatoreb]

1 minute ago, EricJ said:

That amount of force would also likely have g-loc'ed all of the occupants, so the only horror was probably the few moments that led to the tail failure.

I suspect you are right.  I hope you are right.  That they were spared a horrifying death fall for 60 seconds.

[Hank]

46 minutes ago, aviatoreb said:

I suspect you are right.  I hope you are right.  That they were spared a horrifying death fall for 60 seconds.

The posted ADSB data showed 18,000 to 30,00p fpm descent for 2000 feet. It didn't take long . . .

Even if that's wrong, he likely yanked coming out of the clouds at ~1000' agl. That fall was mere seconds. 

[carusoam]

7 hours ago, hypertech said:

Are the control rods really that strong?  I would have guessed that the pin holding the yoke would come off before a control input could break the wings.

The forces we are discussing are aerodynamics and have great multiplying strengths…

We are all trained the same, way back when…

Maneuvering speed is a proven method of controlling the mechanics to prevent tearing flight controls off… and breaking things…

So… in the type of failure that is being discussed here… control rods are pretty safe from destruction in the usual push / pull application…

When out of rig, control rods are really easy to bend and break…

Mechanical multipliers are always present…

 

Above maneuvering speed… full application of any controls is extremely un-recommended…

Wow… that leaves a lot to be interpreted doesn’t it…?

 

Lets say you break out of the clouds, while your asi is screaming past Vne… and your windshield is filling up with trees and houses…

Pray and go gently on the controls… or avoid getting into this situation all together…

Our best defense, is to avoid the loss of control, at low altitudes…

The last ditch effort is to use all of the space available… throwing out all the drag you can…

know that the drag mechanisms are not tested to be deployed above Vne either…

 

In the automotive world… we see a lot of similar limitations… it is really hard to break the steering mechanisms… and we can’t use full control inputs after certain speeds…

Going down the highway near the speed limit is OK…. A deer jumps in front of the car 1k’ away….   Depending on how you react…. loss of control is nearly guaranteed if you jerk the wheel hard… and slam on the brakes…

(sort of an extreme discussion to make a point about mechanical systems we are familiar with)

hmmm….  Some cars are better than others… some drivers have more currency than others….

PP thoughts of what to do in similar situations in the future, not looking back on what could have been done differently in the past… not a CFI either…

Best regards,

-a-

[EricJ]

49 minutes ago, 1980Mooney said:

Most of the discussion in the “wing spar failure?“ topic focuses on the fact that the tail (Horizontal stabilizer) is an inverted wing that creates a downward force - in order to keep the nose up. Loss of the tail causes the plane to  nose down. 
 

The only way to pull out of the dive was for the pilot to violently force the tail down.  Most likely the pilot induced pitch-up caused the wing spar to fail. 

When a surface is failing it can twist under the prevailing forces and will go in whatever direction the forces move it based on where the failure starts and how it progresses.   A stab that fails with the leading edge moving down can generate a sudden pitch-up while it is failing.    I don't think any pilot, even with a full, intact tail, can generate enough pull to induce the sort of g's that will fail a spar on a Mooney (or just about any airplane, as that would be considered a dangerous design).  Less so if half the tail is missing.   I think if it were possible there would have been a lot more such events in history.

There are many videos online of rc aircraft experiencing failures due to flutter or other structural issues, and some vids of full-sized aircraft in the same circumstances.   The violence of the resulting maneuvers is telling.

This isn't quite the same thing, but it shows the sort of violent induced maneuvering that can happen during a structural failure:
 

 

 

[Hank]

Wow, the tail broke, causing a sudden turn, followed by more failures that caused strange gyrations, then nose down towards the ground, periodically going nose up even after the pilot ejected. Hit the ground tail low, too . . .

[DJE22]

6 hours ago, Hank said:

Wow, the tail broke, causing a sudden turn, followed by more failures that caused strange gyrations, then nose down towards the ground, periodically going nose up even after the pilot ejected. Hit the ground tail low, too . . .

Wow, indeed!  I paused the video just prior to the first failure then slowly (almost frame-by-frame) moved the video forward as each gyration and failure occurred.  Even though I knew the pilot ejected I felt myself tense until the frame(s) when the ejection occurred. @Hank your description tells us a lot….revisits the discussions of this accident weeks ago.

[jlunseth]

Yes to what Eric said. The classic analysis that the elevator pushes down to keep the nose up just is not applicable in this situation. For one thing, that analysis assumes a low speed flight regime - the closer the aircraft is to stall the more the elevator/stabilizer is needed to increase the angle of attack of the wing. However, that analysis, for one thing, forgets that the elevator on a Mooney is a movable flight surface. As we all know, the Mooney tail looks forward on the ground. That is because we just landed, and in doing that, we trimmed back (up) to generate low speed lift. But at cruise we look like a Cherokee, the empennage has been trimmed so that the tail is back and the angle of attack of the elevator has decreased dramatically, or even gone negative to keep the plane level as airspeed and therefore wing lift increases.  Combine that with the fact that the attached elevator can be used to pitch the aircraft down, even dramatically down, and you have an adjustable airfoil that can generate lift in either direction, not just down to keep the nose up, but up to put the nose down.

Then you have regime of flight questions. If an aircraft does into a steepening dive it begins an outside loop. In an outside loop, what keeps the aircraft in the loop? A centripetal force. What is that force? It is wing lift that varies from neutral to negative (lift toward the belly of the aircraft).

We don’t at this point know exactly what the attitude of the aircraft was when it began to come apart, but it is a good bet that it was in an accelerating dive or steep downward spiral. The wing would have failed in whatever direction it happened to be making lift when the departure of the stabilizer ceased to counterbalance that lift. If the wing lift was positive the result would have been a very abrupt, almost explosive, positive change in the angle of attack, possibly even to the point where the wing was flying more like a flat piece of plywood into winds well over 200 mph. That will crack the wing spar on any normal category aircraft and probably would even challenge an aerobatic wing.

It’s possible the pilot created this accident with a sharp pull up, maybe. But. How does that explain the departure of the counterweight from the left elevator. Flutter, and tearing of the elevator explains the departure of the counterweight, followed quickly by the departure of the left elevator itself, then the stabilizer, and the aircraft simply ceases to fly.

[Aerodon]

3 hours ago, jlunseth said:

How does that explain the departure of the counterweight from the left elevator. Flutter, and tearing of the elevator explains the departure of the counterweight, followed quickly by the departure of the left elevator itself, then the stabilizer, and the aircraft simply ceases to fly.

Maybe thats the start of the whole sequence.  Pilot or mechanical induced failure of the elevator counterbalance.  Flutter tears the elevator and stabilizer off.  

I'm still having trouble rationalizing the upward failure of the wings.  Maybe it did in fact tumble forward, but broke on a 270 degree rotation.

I've looked at the Canadian Mooney GI-275 incident report - pretty wild gyrations, severe overspeed.  I'm amazed that it was signed off to fly again, that wing was stressed enough to cause fuel leaks and gear not retracting properly.  Brings to mind the tragic end result of the bent King Air in Hawaii from a previous wild ride.

I sure hope the 'tail replacement rumours' are not true. Or if they are, they are not related.

 

Aerodon

 

 

[Aerodon]

Maybe we are overthinking this.  If you look at the Partenavia P68 crash on youtube, the wings failed first (upwards) and it looks like one half of the stabilizer failed as well afterwards.

Maybe some planes stabilizers fail first, followed by a forward pitch and downward wing failure, others have the wing failure first followed by stabilizer?

I know of a Commander 695 that got a bent wing when the pilot realized he had blown through his assigned altitude on descent and pulled before he thought.  

Aerodon

 

 

 

[jlunseth]

1 hour ago, Aerodon said:

 

I'm still having trouble rationalizing the upward failure of the wings. 

 

Why? At least two others broke by that mechanism except they happened to be in an attitude that caused abrupt negative lift rather than positive.

[jlunseth]

It’s in the video that I posted a couple of times, of the stabilizer and elevator on the ground where they were found. https://www.fox9.com/news/neighbors-ran-to-help-after-plane-crash-in-victoria-minn

The elevator and stabilizer footage starts at 2:15. I found the video controls a little quirky, it may take a few tries to get the video to stop where you want it. The notch for the counterweight is still present in the end of the stabilizer but the counterweight is gone from the elevator. I also found video that I cannot find any longer, showing what I assume is an NTSB workman carrying the elevator, where it is in two pieces, broken or maybe folded to carry in one hand. However, it does not appear to be broken in the above video.

[Shadrach]

8 hours ago, jlunseth said:

Yes to what Eric said. The classic analysis that the elevator pushes down to keep the nose up just is not applicable in this situation. For one thing, that analysis assumes a low speed flight regime - the closer the aircraft is to stall the more the elevator/stabilizer is needed to increase the angle of attack of the wing. However, that analysis, for one thing, forgets that the elevator on a Mooney is a movable flight surface. As we all know, the Mooney tail looks forward on the ground. That is because we just landed, and in doing that, we trimmed back (up) to generate low speed lift. But at cruise we look like a Cherokee, the empennage has been trimmed so that the tail is back and the angle of attack of the elevator has decreased dramatically, or even gone negative to keep the plane level as airspeed and therefore wing lift increases.  Combine that with the fact that the attached elevator can be used to pitch the aircraft down, even dramatically down, and you have an adjustable airfoil that can generate lift in either direction, not just down to keep the nose up, but up to put the nose down.

Then you have regime of flight questions. If an aircraft does into a steepening dive it begins an outside loop. In an outside loop, what keeps the aircraft in the loop? A centripetal force. What is that force? It is wing lift that varies from neutral to negative (lift toward the belly of the aircraft).

We don’t at this point know exactly what the attitude of the aircraft was when it began to come apart, but it is a good bet that it was in an accelerating dive or steep downward spiral. The wing would have failed in whatever direction it happened to be making lift when the departure of the stabilizer ceased to counterbalance that lift. If the wing lift was positive the result would have been a very abrupt, almost explosive, positive change in the angle of attack, possibly even to the point where the wing was flying more like a flat piece of plywood into winds well over 200 mph. That will crack the wing spar on any normal category aircraft and probably would even challenge an aerobatic wing.

It’s possible the pilot created this accident with a sharp pull up, maybe. But. How does that explain the departure of the counterweight from the left elevator. Flutter, and tearing of the elevator explains the departure of the counterweight, followed quickly by the departure of the left elevator itself, then the stabilizer, and the aircraft simply ceases to fly.

Sorry, but I disagree with this analysis. The tail of any mooney loaded within CG limits (especially a long body), at any speed produces downforce. Trimming for level flight will produce more or less downforce as needed but it never becomes a lifting tail nor does the tail sweep back like a “Cherokee” in cruise.