How strong is the M20 wing?

[cnoe]

In light of the recent Pilatus breakup and some older Bonanza incidents I've been reading about proper handling of an excursion into slow spirals in IMC. Of course the best solution is "don't go there" and that's one reason I have a backup Attitude Indicator (electric) as well as a backup vacuum pump, but...

 

If I were to realize that I'm in IMC banking, with the altimeter unwinding and the DG (or compass) turning the obvious first action is to simultaneously LEVEL THE WINGS and REDUCE POWER. I've done this many times in the past year as well as during my recent Instrument Checkride. No problem.

 

But my question relates to a situation where the scan also shows the IAS nearing Vne. I know, "don't go there", but if it happened I'd want to be certain of the best course of action.

 

Evidence I've read from the Pilatus case suggests that simply unloading the elevator and letting the trim do all the work might suffice. But there was a heated discussion on the Beech site arguing the merits of "pulling" on the yoke, with some even arguing for a "push" as the trim took over flight attitude. To minimize airspeed gain and altitude loss a respected member of the forum suggested that one should "pull" to the design limit of the wing ASAP, and if the ground was quickly approaching one should pull BEYOND the design limit reasoning that "bent wings are preferable to ground impact". This seems reasonable to me, but without a g-meter how am I to know how hard to pull? It was oft repeated that a typical pilot "thinks" they're pulling 4+ g's when they're really only pulling something like 2.5.

 

So... how strong IS the M20 wing, and how hard should one pull on the yoke if inadvertently approaching Vne in a dive?

 

 

[gsxrpilot]

There is a story told, (I can't recall where I heard it now) of a Mooney that went down in a box canyon somewhere in the North West. The pilot pulled the Mooney out of a dive in IMC and was estimated to pull some ridiculous G's in the neighborhood of 8 or 9. The pilot went to the hospital with massive internal injuries while the Mooney was disassembled and sent to Kerrville. The story is the wing was only 1/4" out of square and immediately popped back straight after the skins were removed. Supposedly the aircraft was repaired and returned to service.

 

Probably some others on this forum can recount this better than I.

 

I don't think you could possibly break the Mooney wing in flight. I would think the tail was the weak link in the chain.

[markejackson02]

Assuming you didn't move the trim, I wouldn't pull at all.  If you level the wings, you would probably end up pushing pretty hard as the wing will seek it's trimmed speed resulting in a huge pitch up.

[carusoam]

So many different ways of avoiding unusual attitudes, from panel mounted devices to I-technology back-ups to portable electronic HSI...

Maneuvering speed for gross weight are important to know while flying, as are G limits for normal category planes.

A couple of well trained steps for recovering from unusual attitudes....

You will be hard pressed to find Mooneys that have bent a wing from pulling Gs.

Avoid trees. Trees have been known to bend more Mooney wings than I would want to count.

If you are spiraling close to the ground, will you be looking at the G meter?

If yes, get a G meter. Go electronic with a memory. After the plane's demise, you will want to know what Gs you experienced.

If you get one minute to save your life, you may have really clear thought processes. Not everyone experiences brain freeze in stressful low(ish) level oxygen saturation situations. Follow your training.

I am probably misunderstanding your question. I enjoy the thought process that goes into the answers...

Best regards,

-a-

[RobertGary1]

Often times upsets occur in sever turbulence. In that case you can't rely on the plane going back to level flight based on the trim setting. It will require positive control.

-Robert

[mike_elliott]

It would be interesting to find out how many G's it takes to break the Mooney wing. I know I hit the ground hard enough last year in a bravo to have snapped it at the fuselage. Man, that hurt.

Stacey, got your ears on? any Engineering data to share? Ill ask Bob Kromer at the Mooney Summit for sure to see if he knows.

 

mike "cementhead" elliott

[KSMooniac]

I remember seeing a K on ebay several years ago that looked suspicious, and I followed the N-number back to an NTSB report.  The pilot penetrated a t'storm in eastern CO and got spit out the bottom fairly violently, necessitating a huge pull-up to recover control before hitting the ground.  He later made a successful landing and even flew a few more times before discovering some popped rivets and buckled skins on the wing.  It had permanently deformed upward a little bit... and I can't remember the G-estimate from the NTSB but it was substantial.  He made an insurance claim and the plane was totaled.  (and later resurrected on ebay after repairs)

 

I agree that the tail is likely to leave the plane first, but you would have to really aggravate the plane for that to happen.

[carusoam]

The factory reported testing the wing, back in the day...

The test stand broke before the wing did.

Look for the picture of the thirty or so factory employees standing on the wing.

As Mike points out above, hitting hard objects like the ground or trees is the more important focus.

A single point focus on strength of one wing and not the other, or the strength of the fuselage under ideal test conditions...

This will leave you focussed on one important point and possibly missing other equally important details.

Even Brand B didn't bend the wing, as much as it ripped the tail feathers off...?

From Brand B we learned... Avoid flying into thunderstorms, if you do, slow down while turning away from them. Maintain control.

Best regards,

-a-

S from K is a fast typer...

[PTK]

It would be interesting to find out how many G's it takes to break the Mooney wing. I know I hit the ground hard enough last year in a bravo to have snapped it at the fuselage. Man, that hurt.

Stacey, got your ears on? any Engineering data to share? Ill ask Bob Kromer at the Mooney Summit for sure to see if he knows.

 

mike "cementhead" elliott

And I'm certainly very happy you're here to talk about it Mike!

[PTK]

I have searched but haven't been able to find data specific to Mooney inflight breakups. I remember some years ago there was mention of the only Mooney breakup was a Missile or Rocket. I don't remember which.

[DanM20C]

A local K model had an bad icing encounter at 11K this last December.  They didn't recover until 1500 msl.  I have only heard 3rd hand stories about the actual incident but I did look over the plane in the hanger afterward. It was totaled. The entire top skin of both wings had ripples all the way down the spar.  Some popped rivets and the fuel tanks leaked.  The guys salvaging the airplane said they were originally planing on fixing it, but after tearing into it found it wasn't worth it.  I'm amazed the tail stayed on and I'm convinced a bonanza wouldn't have stayed together in a pull like that.  My Bonanza friend agreed but said a Bo would have carried the ice better.     

 

Regards,

Dan

[PTK]

This thread reminds me. A physics review of Va and g loads may not be a bad idea!

The relationship between Va and turbulence is defined by Newton's 2nd Law, a=F/m. Acceleration, a, is inversely proportional to mass, m. For a given force F a lighter object will accelerate faster than a heavier one. Recall that our airplanes' load characteristics are expressed in g's which is an acceleration quantity (aka acceleration due to gravity.) To be sure we don't exceed our airframe's g load acceleration we need to be sure that according to a=F/m, a (or g) remains within safe margins.

The only way we can control this is through airspeed! This is also due to F=ma because speed is directly proportional to force F. Force F is thus a function of airspeed! The lighter airplane is unable to withstand the same maximum force F as the heavier one. Simply because the lighter one accelerates easier and will exceed its g loading.

This is why a lighter airplane needs to be flown slower in turbulence!

[rbridges]

Marauder lets his babes walk on the wings.  Enuff said.

[Marauder]

It would be interesting to find out how many G's it takes to break the Mooney wing. I know I hit the ground hard enough last year in a bravo to have snapped it at the fuselage. Man, that hurt.

Stacey, got your ears on? any Engineering data to share? Ill ask Bob Kromer at the Mooney Summit for sure to see if he knows.

mike "cementhead" elliott

The factory reported testing the wing, back in the day...

The test stand broke before the wing did.

Look for the picture of the thirty or so factory employees standing on the wing.

As Mike points out above, hitting hard objects like the ground or trees is the more important focus.

A single point focus on strength of one wing and not the other, or the strength of the fuselage under ideal test conditions...

This will leave you focussed on one important point and possibly missing other equally important details.

Even Brand B didn't bend the wing, as much as it ripped the tail feathers off...?

From Brand B we learned... Avoid flying into thunderstorms, if you do, slow down while turning away from them. Maintain control.

Best regards,

-a-

S from K is a fast typer...

I can't remember if it was Bill Wheat who told me the story about the wing loading jig failure during certification but I remember it was over 10 Gs.

[N201MKTurbo]

I have heard that Mooney Hired Al Pietsch from ND to do dive tests on the Mooney. I heard that he took it to over 300KTS and pulled in excess of 9Gs without any damage.

 

You could call his son Warren Pietsch at Minot Aero Center for more details.

[mike_elliott]

And I'm certainly very happy you're here to talk about it Mike!

Thank you Peter. While we roll around every now and then like a couple of baby raccoons, I have a great deal of respect for you and of course wish you the best always! 

[PTK]

Marauder lets his babes walk on the wings.  Enuff said.

I don't think he has any choice but "let" them!

They'll smack him silly if he refused!

[KSMooniac]

The only in-flight breakup I've read about was another t'storm penetration (at night, no less) in east TX or west LA.  I don't remember which model it was, unfortunately.  Perhaps there have been others, but that is the only one I know about out of 10,000+ Mooneys in the fleet.

[PTK]

Thank you Peter. While we roll around every now and then like a couple of baby raccoons, I have a great deal of respect for you and of course wish you the best always!

Thank you Mike. You're very kind!

I have the utmost respect for you also. My hat's off to you my friend!

[Marauder]

Marauder lets his babes walk on the wings. Enuff said.

Well, every time they got on the wing walk, fuel would gush out of the vent. It was just getting to expensive...

Sent from my iPad using Tapatalk

[AndyFromCB]

There was one here over Lincoln, NE few years back that pulled 12G in a thunderstorm, landed with the wingtips about 6 inches higher than original, but landed ;-) 12G was factory estimate in order to cause the damage that it did...It takes a lot to break a Mooney. I know I tend to black out around 6Gs if I'm not ready for them and straining...which means I will probably break before the airplane does...

[MB65E]

Warren, is an outstanding guy that can fly the snot out of a Taylorcraft!!!

-Matt

[Glenn]

You would be wise to avoid the rolling pull-up.  Level the wings and reduce power if you are fast.  Once the wings are level you can pitch up if needed.

[Bennett]

Not that you would want to spend much time reading the gauge, but the Dynon D-2. Portable EFIS had a G meter (page 2) that reads up to +6 Gs, and - 4 Gs.

[cnoe]

In the Bo forum the thinking was that their tail-feathers departed due to air-speed induced flutter long before any ultimate g-load was surpassed. If the 300 kt/mph test flight is true then it's nice to know that "flutter" is not a primary concern. And it also sounds like g-loading of the wing isn't a huge concern either.

 

I've seen the pic of the factory guys standing on the wings, and I've also heard the tale of the test-jig breaking, but I didn't know the related numbers. It would be interesting to hear the "numbers" from an authoritative source.

 

If the wing and airframe are as strong as legend has it then I'd likely pass out well before breaking the wings off in a simple "pull" from a steep dive. Does anybody disagree?