Pitch control emergency

[takair]

17 minutes ago, PT20J said:

Heim is actually a trade name -- now owned by RBC bearings. They are also know generically as rod ends.

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Old habits are hard break. Ironically RBC headquarters is about a mile from my home. 

[MooneyMitch]

2 minutes ago, takair said:

Old habits are hard break. Ironically RBC headquarters is about a mile from my home. 

Examples........I’ll make a Xerox of that.......do you have an Allen wrench........I need a Phillips screwdriver..........the list goes on and on and on....

[N231BN]

I have replaced that before due to a identical failure, it's a pretty easy job.

 

I'm pretty sure I still have the parts, I'll look around.

 

[PT20J]

41 minutes ago, takair said:

Old habits are hard break.

Me too -- I still reach for a Kleenex. It's one of the powers of branding. I only pointed it out so that the newer folks would know that there are a couple of names for the same thing. Aircraft parts names and numbering systems are so confusing. 

[carusoam]

We were reaching for Vernatherms the other day...  yes, a brand name...  

-a-

[MooneyMitch]

Vaseline......another example of name branding.

The correct name for the product is of German origin....... der vennie schlider ! 

[N201MKTurbo]

53 minutes ago, MooneyMitch said:

Vaseline......another example of name branding.

The correct name for the product is of German origin....... der vennie schlider ! 

So, back in the 30s, oil well workers noticed this stuff in the drill pipe. They wondered what it was. Somebody decided to make a profit with it. In WWII, all the guns and part were preserved with Cosmoline, guess what, Same stuff! It helped win the war. You can still find guns and stuff preserved in the stuff, and it is like brand new. And it is good for your skin. 

[ragedracer1977]

38 minutes ago, N201MKTurbo said:

So, back in the 30s, oil well workers noticed this stuff in the drill pipe. They wondered what it was. Somebody decided to make a profit with it. In WWII, all the guns and part were preserved with Cosmoline, guess what, Same stuff! It helped win the war. You can still find guns and stuff preserved in the stuff, and it is like brand new. And it is good for your skin. 

I've got an old Chinese knock off of a Moisin Nagant.  It was literally in a 55 gallon drum with about 30 other rifles, filled to the brim with cosmoline.  I spent a LONG time cleaning it.  Still, 15 years later, if I leave it in the sun, more cosmoline leaks out of the wood.

[KB4]

On 9/25/2020 at 9:59 AM, WaynePierce said:

How can you even inspect this part on my J? Is there a plate there? Not at the plane or I'd look, but I will be later today and I will.

At the hinge.  Same panel you remove to lube the jack screw inside that black boot.  More room and light if you remove both sides.

[N231BN]

Here is the broken part. It is a "T" extrusion and it looks like the extrusion die left some lines in the part that possibly created a stress riser contributing to the failure.

I believe I bought a replacement from LASAR.

[Sam Judd]

@Freemasm - Note that the part picture is from a different poster. Maybe they also have experienced a similar failure? 

[N231BN]

1 hour ago, Sam Judd said:

@Freemasm - Note that the part picture is from a different poster. Maybe they also have experienced a similar failure? 

I mentioned earlier in the thread I had repaired a 201 that had a similar failure. I guess it got lost in the chatter about Vaseline...

Anyway, the part was original to the airplane. I'm sure I blasted it with plastic beads to get a better look at the failure.

[LANCECASPER]

On 9/25/2020 at 9:19 PM, MooneyMitch said:

Vaseline......another example of name branding.

The correct name for the product is of German origin....... der vennie schlider ! 

They were referring to brand names of parts Mitch, Vaseline is referring to labor charges.  

[EricJ]

1 hour ago, LANCECASPER said:

They were referring to brand names of parts Mitch, Vaseline is referring to labor charges.  

Ohhhh, I thought the vaseline was for the anal inspection.   Still not sure about the whole thing, but maybe it helps.

On 9/25/2020 at 10:56 AM, Freemasm said:

...

Bead blast, anally inspect, then re-prime both exposed bulkheads. 

...

 

[JRo]

@Sam Judd, glad you landed safely.

[carusoam]

BN’s part really looks like the extruder die lines aided in the direction of the failure...

Wasn’t expecting that to be so well pronounced...

PP thoughts only, not a mechanic..

Best regards,

-a-

[jaylw314]

On 9/25/2020 at 8:21 PM, N201MKTurbo said:

So, back in the 30s, oil well workers noticed this stuff in the drill pipe. They wondered what it was. Somebody decided to make a profit with it. In WWII, all the guns and part were preserved with Cosmoline, guess what, Same stuff! It helped win the war. You can still find guns and stuff preserved in the stuff, and it is like brand new. And it is good for your skin. 

One of the initial uses of petroleum jelly was as an alternative to butter on toast in tropical climates.  That thought kind of gives me the squickies...

[Sam Judd]

After some back and forth with the FAA and the NTSB, my mechanic was vale to work out a temporary repair and a ferry permit today so I could bring the plane back to the shop. It sounds like @Freemasm is right and the fix will involve some fairly substantial surgery including removing the tail and/or trim assembly.

 

I did get a few more pictures of the part: https://photos.app.goo.gl/6UsusgKjthD5cxncA. To my untrained eye, it looks pretty much identical the other failure shown in this thread.

My mechanic will save the part, but we have to give the FAA first crack and the factory probably gets the second. If neither of them want it, I'll get hold of it and work with @Freemasm.

 

I'll also follow up a bit more with the process around communicating with the FAA/NTSB later on. So far everyone has actually been quite responsive and helpful, but I'll save detailed comments until this is definitively over. 

[carusoam]

Sam’s link, just slightly more live...
 

Looks like lots of metal flake was ejected with the failure...

which could have been instantaneously deposited... if it had failed slowly over time, there may have been a few days during an annual that those flakes would have stood out to good mechanical inspector...

https://photos.google.com/share/AF1QipN95icT-rkpXrkJCdSpbqeXXLT3PWJb3siWQ52RX4httQ_vNZEB67zMBHgFquWTkw?key=cnJGbmFKRFJCZkpqbGhRRkI3MlhuY21reWRTTDlB

-a-

[PT20J]

Hard to see how there would be a bending moment given the rod ends on each end of the tube and the linear action of the tube. The attached drawing from the M20J IPC only shows a rod end at the aft end, but the parts list does call out 2 for the assembly. My annual inspection is scheduled in a couple of weeks - I’ll be looking this part over very closely.

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[PT20J]

6 hours ago, Freemasm said:

A properly torqued bolt through a bearing would yield more of a shear load but a bending load still exists as there is a offset between the bearing and bracket. This would be aggravated if not properly torqued.

This is correct, of course. I overlooked the offset. Thanks for pointing that out.

I was at the hangar today and decided to take a look at my 1994 'J. A couple of observations:

1. The bracket appears to be an aluminum T extrusion. The thickness of the "stem" to which the tube attaches is only about 0.08".

2. Mine shows a very slight bending of the "stem" to the outboard (presumably due to the offset pull force of the tube that attaches to the trim assist bungees). This is evident in the picture if you look closely.

I don't think this is a very robust design.

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[Hank]

2 minutes ago, PT20J said:

This is correct, of course. I overlooked the offset. Thanks for pointing that out.

I was at the hangar today and decided to take a look at my 1994 'J. A couple of observations:

1. The bracket appears to be an aluminum T extrusion. The thickness of the "stem" to which the tube attaches is only about 0.08".

2. Mine shows a very slight bending of the "stem" to the outboard (presumably due to the offset pull force of the tube that attaches to the trim assist bungees). This is evident in the picture if you look closely.

I don't think this is a very robust design.

Skip

 

It's lasted 30 years with sufficiently minor deformation that you have to look very closely to see it, but it's not a robust design? How long should it last? Mine's 20 years older, but it'll be sometime next week before I can look at it. 

[EricJ]

25 minutes ago, PT20J said:

This is correct, of course. I overlooked the offset. Thanks for pointing that out.

I was at the hangar today and decided to take a look at my 1994 'J. A couple of observations:

1. The bracket appears to be an aluminum T extrusion. The thickness of the "stem" to which the tube attaches is only about 0.08".

2. Mine shows a very slight bending of the "stem" to the outboard (presumably due to the offset pull force of the tube that attaches to the trim assist bungees). This is evident in the picture if you look closely.

I don't think this is a very robust design.

Skip

 

Ouch, that hurts just looking at it.   Based on the IPC excerpt you posted earlier it seems like maybe sometime along the way this was a double-shear attachment that got converted to a spherical rod end.   I don't think that conversion got implemented optimally.

The bracket could have been double-shear (a U to both sides of the rod end) but would have been more expensive to make.  I think this is a good item to add to the annual inspection list if it is implemented like this.  Now I gotta go look at mine sometime...

[0TreeLemur]

On 10/8/2020 at 9:59 PM, PT20J said:

I don't think this is a very robust design.

 

Agreed.  Much more susceptible to the observed failure mode that started this thread than the design using the stamped part.  Requires careful inspection for fracture indications.  Luckily this failure does not result in an unrecoverable situation in a J. 

I wonder how this failure would affect the pitch control in a short body?   Anybody with a short body ever lived through this?

There are aircraft in museums that are newer than my C.  Next annual I'll spend extra time inspecting that little piece of extruded aluminum.

[N201MKTurbo]

On 10/8/2020 at 7:59 PM, PT20J said:

This is correct, of course. I overlooked the offset. Thanks for pointing that out.

I was at the hangar today and decided to take a look at my 1994 'J. A couple of observations:

1. The bracket appears to be an aluminum T extrusion. The thickness of the "stem" to which the tube attaches is only about 0.08".

2. Mine shows a very slight bending of the "stem" to the outboard (presumably due to the offset pull force of the tube that attaches to the trim assist bungees). This is evident in the picture if you look closely.

I don't think this is a very robust design.

Skip

 

You don't have the correct hardware. The IPC shows a castellated nut with a cotter pin.