Pitch control emergency

[carusoam]

Great work @Freemasm

Consider leaving this out...   it doesn’t help where you are going...

“Don't expect any back and forth from me. One thing that appears to be common with forums, the loudest objectors tend to know the least about the topic. ”

It is more of an invite, than a method to avoid, confrontation....

Stay focussed on the topic...

Some people are loud, and they are smart too...

We have plenty of not smart people around here too, and they count equally as much as the smart ones...

MSers are all smarter than the users of the other forums they attend...

Loud PP thoughts only, not a quiet bystander... 

Best regards,

-a-

[Sam Judd]

"""

The fracture surface appears to be unoxidized. Reference photo. That suggests that either the fracture occurred fairly recently or it was well protected from corrosion. (possible but doubtful. The OP will hopefully expand here).

"""

The airplane was tied down at WVI outside. It's been outside or under a shade cover for the last two years. The previous owner said it had been hangared in CA and then NM  until I got it. 

 

Thanks for the detailed report @Freemasm, fascinating read!

[Ragsf15e]

22 minutes ago, Sam Judd said:

"""

The fracture surface appears to be unoxidized. Reference photo. That suggests that either the fracture occurred fairly recently or it was well protected from corrosion. (possible but doubtful. The OP will hopefully expand here).

"""

The airplane was tied down at WVI outside. It's been outside or under a shade cover for the last two years. The previous owner said it had been hangared in CA and then NM  until I got it. 

 

Thanks for the detailed report @Freemasm, fascinating read!

It’s a little spooky.  If it was nicely corroded, we could all blow it off by saying ours is in a hangar, cleaning it, inspecting it, spraying acf on if or whatever.  It appears it’s a fatigue issue and would be really difficult to prevent.  I’m glad it was controllable, but I don’t want to be next!

How much did the repairs cost?  Where did you get a new bracket?

[Sam Judd]

5 minutes ago, Ragsf15e said:

It’s a little spooky.  If it was nicely corroded, we could all blow it off by saying ours is in a hangar, cleaning it, inspecting it, spraying acf on if or whatever.  It appears it’s a fatigue issue and would be really difficult to prevent.  I’m glad it was controllable, but I don’t want to be next!

How much did the repairs cost?  Where did you get a new bracket?

The bracket came from the factory, they just happened to have one in stock.

 

The final repair was ~6.8 hours and around $850. The part was just under $61. While my mechanic is one of the very well known west coast Mooney shops, this was the first time they'd seen this particular failure. They tried a couple of things before finally removing the tail to get access to the area with a rivet gun. It's possible that it'll be somewhat less for the next person now that they know what to do. 

 

An additional 6 hours was billed for travel to/from the airport where I was stuck and attaching the the replacement bracket with cherry rivets for a temporary flight permit so I could get the plane to my mechanics airport.  

[Ragsf15e]

3 hours ago, Freemasm said:

@Sam Judd Your parts have been returned to me from the lab. I’ll have them on the way to your coast by this weekend. Will send PM a tracking number when available. I need to get back out there and to Napa again soon.

@carusoam You probably didn’t misunderstand my disclaimer but I won’t say the same for the intent.  I’ll help anyone with anything whenever I’m able; bucking rivets, analyzing issues, whatever. When trying to help someone here, I do usually at least try to explain the rationales or principles behind my statements. If I misunderstand something or am wrong, someone will let me know.  I respect that. I offer most of my help through PMs these days but due to the nature of this specific issue thought open discussions here was best.

I didn’t see any request for more info or explanation from my preceding post so I’ll assume I was able to convey things pretty clearly. From other past threads when someone disputes something over anecdotal “proof” or because they heard it from xxx or yyy without providing any backing technical rationale, it’s a much different story. The aforementioned is a common tactic here and other places. As you stated, they have their right to their public opinions. I don’t feel obligated to indulge; in fact, it feels so wasteful and non-productive.

My BS detector goes off each time someone hints or quotes at the unnamed Mooney/Lycoming/Hartzell, engineer as the source of their knowledge. Because someone’s cousin said so and “he used to work on the Space Shuttle” (I actually was an engineer on such for eight years; a very overrated experience) doesn’t bring credibility. The guy that justifies his dangerous behavior because “My friend’s (probably himself) been burning car gas in his Bonanza for years” no longer gets my attention either.  BTW, none of these examples are made-up.

Anyway, this was an honest and open effort that I hope helped. I figured I was in a fairly unique position to be of help due to my resources.  Speaking of which, I’m most grateful to the lab guys whose efforts really nailed things down. I make no apologies for any perceived lack of political correctness. In the end, it probably saved time and potential confusion. 

PP only. Not a politician. Just someone trying to help and is surprisingly, actually liked by those that know him.

Best of luck to you both, Sirs.

I actually did have a question... which side of the bracket are the fatigue indicators and the initial stress fractures from forming the part?  It seems to me that the offset in the rod connection (assuming the rod is under tension) would put the “pilot side” of the bracket in compression and the side of the bracket that faces the copilot side in tension.  That copilot side is very hard to clean, paint, and inspect because it’s between the trim rod boot and the rod connected to our failed bracket.

If the failure started on the joint facing out the inspection cover (pilot side), It would seem there was some torsion or something else going on there to start it.  
 

Looking closer at your pictures, it looks like the inside joint I think?  Near the top too.  I wonder if that rod could be at an unplanned angle or something?

Edited January 14, 2021 by Ragsf15e

[carusoam]

Freemasm,

You have done an incredible service...

Great support for the entire community...

Where else could we have a knowledgable discussion on Mooney metallurgy..?

We still get spelling and grammar lessons thrown in...

Go MS!

-a-

[tmo]

13 hours ago, Freemasm said:

I didn’t see any request for more info or explanation from my preceding post so I’ll assume I was able to convey things pretty clearly.

Your post is great. Much of what you say is "above my pay grade" but I hope that in time of need the right neurons will fire and it will all "click". Thank you!

[PT20J]

Seems bad practice to leave tooling marks at a point of maximum stress. 

[skykrawler]

Skip,  it does seem like yours have been apart.

I inspected mine yesterday, but it seems like pending failure may not be detectable.  It also seems like there might be a relationship to lack of lube in the system.

I wonder, would be acceptable to use AN cap screws rather than rivets for a replacement installation?

[PT20J]

1 hour ago, skykrawler said:

Skip,  it does seem like yours have been apart.

I inspected mine yesterday, but it seems like pending failure may not be detectable.  It also seems like there might be a relationship to lack of lube in the system.

I wonder, would be acceptable to use AN cap screws rather than rivets for a replacement installation?

I don’t think it’s ever been removed. There is nothing mentioned in the logbook and the “new” looking rivet seems to be a trick of lighting in the photo. I have some other photos where the rivet does not appear different than the others. 

The only things I can see to lube are  be the heim bearings at each end of the rod and these are well lubed and free on my airplane. 

You’d have to discuss the idea of bolting it on with your IA. But, I don’t see that it would have any benefit other than to make it easier to replace the part if it fails again.

Skip

 

 

[mhrivnak]

I found this thread while looking for discussion of the bolts and nuts for the elevator controls. At my home airport, we recently noticed that 3 out of 3 Js have lock nuts for all of the visible rod ends in the tail, while the IPC shows castellated nuts with cotter pins. From memory it's at least 5 or 6 bolts, most of which are a real pain to get to (par for the course I guess). From that and other posts on MS, it seems like a lot of planes must have come from the factory with lock nuts instead of what the IPC shows. These 3 Js span 1984-1993.

The "don't fix it if it ain't broke" approach makes a lot of sense in general, especially if we suspect the factory sent them out this way. But in this case, the IA responsible for all three is concerned. He points out that the IPC, AC 43.13, and other standard IPCs for brands C, P, etc. all call for a pin to be involved in similar control systems, and that the pin is a safer option.

Has anyone gone through the effort of replacing them all? Is there some Mooney-specific thinking on the wisdom of changing them or not? Seems like it would turn into a big project.

[bmcconnaha]

1 minute ago, mhrivnak said:

I found this thread while looking for discussion of the bolts and nuts for the elevator controls. At my home airport, we recently noticed that 3 out of 3 Js have lock nuts for all of the visible rod ends in the tail, while the IPC shows castellated nuts with cotter pins. From memory it's at least 5 or 6 bolts, most of which are a real pain to get to (par for the course I guess). From that and other posts on MS, it seems like a lot of planes must have come from the factory with lock nuts instead of what the IPC shows. These 3 Js span 1984-1993.

The "don't fix it if it ain't broke" approach makes a lot of sense in general, especially if we suspect the factory sent them out this way. But in this case, the IA responsible for all three is concerned. He points out that the IPC, AC 43.13, and other standard IPCs for brands C, P, etc. all call for a pin to be involved in similar control systems, and that the pin is a safer option.

Has anyone gone through the effort of replacing them all? Is there some Mooney-specific thinking on the wisdom of changing them or not? Seems like it would turn into a big project.

Could you post a picture of where your referencing on the plane?? Mine has lock nuts if it’s where I’m thinking 

[mhrivnak]

29, 43, 44 in this diagram for sure. There were at least a couple others I'd have to stand in front of the plane with the diagram to get oriented on them again. Part 45 is the one for which this thread discusses breakage.

You can see both 29s without taking anything apart if you peek in through the back as pictured.

[N231BN]

If they are all connected to rod end bearings, no pin required as they are non-rotating.

[EricJ]

3 hours ago, N231BN said:

If they are all connected to rod end bearings, no pin required as they are non-rotating.

If the rod end binds or seizes it'll be subject to rotation, so I think that one's a tough call.    A castellated nut with a cotter pin would be a better option, imho, but that's just me.

I checked the IPC to see whether there are alternative fasteners listed, and there don't seem to be.

 

[N231BN]

If the rod end binds or seizes it'll be subject to rotation, so I think that one's a tough call.    A castellated nut with a cotter pin would be a better option, imho, but that's just me.
I checked the IPC to see whether there are alternative fasteners listed, and there don't seem to be.
 

If the bearing seizes you will have bigger problems than what kind of hardware was used.

Every one of those joints on a M20K calls for a lock nut. Perhaps the J manual was carried over from some of the older models. Even the elevator hinges use lock nuts.

[carusoam]

I’m not a big fan of the old style lock nuts… they may tire with age or use and fall off… at least that is what one did on my M20C… the spring fatigued.

Let’s invite @M20Doc to stop by… he may know if there is an update to these fasteners… (lock nut and flight controls)

Best regards,

-a-

[N231BN]

The old style AN363 will lose their tension rather quickly with re-use, a nylock is actually better in that regard. The new solid metal lock nuts are much better, especially the mini ones or "jet-nuts."