Upper cowl machine screw issue on '83 J

[0TreeLemur]

An A&P did some work on my Mooney today.  He and I put the lower cowl on and he left for the day.  While installing the upper cowl I encountered a problem.

The upper cowl on my '83 J has a bunch of quarter-turn fasteners and three machine screws on each side.  Two machine screws go into the stanchion around the propeller flange, and one on the forward corners.  The screw on the right forward corner started normally but after a few turns started to get real tight...   Those are stainless steel screws and it felt like it might be starting to spall.   So I backed it out.  It was tough to turn and definitely felt like it was spalling.  The threads were definitely messed up.

Looking in there, the threads on the inside nut plate are not perfectly aligned with the hole in the nut plate.  The threads on the left front nutplate are centered.   On the right hand side it seems that the nut is too high.  Looking in there I could see a many threads in the bottom of the hole and none in the top.

Question: are those nut plates with captured floating nuts?   Why is it suddenly out of alignment, and how can I center it?   Any ideas on how to fix this?  One Idea I have is to run a tap in there and see if that centers it.  Thought I would ask the collective about this idea before trying it.  

Thanks,

Fred

[Slick Nick]

Just drill out the rivets and put some new nut plates in. 

[0TreeLemur]

2 hours ago, Slick Nick said:

Just drill out the rivets and put some new nut plates in. 

Does not answer my questions at all.

[N201MKTurbo]

There are floating and fixed nut plates. Just look at them and you can tell.

You can also chase the threads with a tap.

[Slick Nick]

10 hours ago, 0TreeLemur said:

Does not answer my questions at all.

Q: "How can I fix this?" 

A: Install new nut plates.

Not sure how that didn't answer your question? 

Most nut plates are squished at the end so they will retain the fastener. Tapping it out removes that, which is why it's best to replace them. Not sure if the cowl ones are like that, but replacing it would be the easiest and most professional solution. 

[N201MKTurbo]

16 minutes ago, Slick Nick said:

Q: "How can I fix this?" 

A: Install new nut plates.

Not sure how that didn't answer your question? 

Most nut plates are squished at the end so they will retain the fastener. Tapping it out removes that, which is why it's best to replace them. Not sure if the cowl ones are like that, but replacing it would be the easiest and most professional solution. 

If you replace them, you will traumatize the fiberglass and paint. Chasing the threads will get it working without screwing up the appearance of the cowl.

[0TreeLemur]

14 hours ago, N201MKTurbo said:

Chasing the threads will get it working.

To answer my own question it is not a floating nut plate so alignment was not the issue.  Running a tap in did clear the way.  It seems odd to me that suddenly it developed a problem.  I can't imagine what caused it to change.

 I suspect that nut plate is going to need replacing sooner rather than later by an A&P with the experience and tools, which I am not.

[jetdriven]

Stainless screws tend to gall and seize up in the nut plate and then break off and then you have one heck of a problem. We just started using more and more cad plates steel fasteners, which don’t do this nearly as often. Spinner screws in M20Js  are another notable example.