Loose nose gear door piano hinge

[0TreeLemur]

Hi everyone, while doing some "social distancing" in the hangar today and giving our C a belly rub, I noticed that the left nose gear door piano hinge is really loose.  The aft screw is gone, and the screws are progressively looser further aft.   These seem like No. 6 sheet metal screws.  Do I just tighten them up and replace the missing one?   Is that it?  Is there some kind of loc-tite that could be applied? 

It seems really dangerous vulnerability.  If this hinge were to separate in on takeoff or approach, dog only knows what would happen but I can't imagine any good outcome.  I don't have an A&P on field to ask.   Anyone seen this before?   Given that the annual was done just last month and they did take the gear off to paint them, this is probably a recent development, with only about 30 hours flown since then.  Thanks for any useful experience-based guidance.

-Fred

 

[RLCarter]

I seem to remember mine had sheet medal screws and I replaced them with machine screws and locknuts

[MooneyMitch]

If my memory serves me correctly, there are spring nuts [Tinnerman nuts] which the screws secure themselves to.   I might suggest replacing the missing one and  tighten the others.

A side note, not sure why the gear doors would need to be removed to remove the truss.  Regardless, try to tighten the screws. 

[carusoam]

Might want to take a real good look at what is in there...

Are they beveled, flush, sheet metal screws?

On the other end of sheet metal screws is some form of speed nut called a tinnerman nut...

Tinnermans are springy devices designed to do the job... over the decades they lose their springiness... and demand replacement...

So look if their is a clip with threads in it... attached at the back side...

 

And... if there is enough space between the closed hinge halfs.... real hardware would make a great option...

The parts catalog will be a great place to see what is there...

Best regards,

-a-

[0TreeLemur]

Just now, MooneyMitch said:

If my memory serves me correctly, there are spring nuts [Tinnerman nuts] which the screws secure themselves to.   I might suggest replacing the missing one and  tighten the others.

A side note, not sure why the gear doors would need to be removed to remove the truss.  Regardless, try to tighten the screws. 

Thanks.  They seem to be regular sheet metal screws.   BTW- I didn't write that they took the gear doors off- I wrote that they took the gear off to paint.   It seems that anyone working down there on such a task would have ample opportunity to notice floppy gear doors??

[MooneyMitch]

6 minutes ago, 0TreeLemur said:

Thanks.  They seem to be regular sheet metal screws.   BTW- I didn't write that they took the gear doors off- I wrote that they took the gear off to paint.   It seems that anyone working down there on such a task would have ample opportunity to notice floppy gear doors??

Yes, they are standard sheet metal screws that screw into the Tinnerman nuts on the other side of the sheet metal.  Sorry, I assumed [bad Mitchell] the door was loose due to removal.  It does seem strange the door would become that loose just over a month out of annual.  Hope this helps you.

P.S.  Also, to access the Tinnerman nuts, the adjacent fairing needs to be removed.  Easy to do, just more sheet metal screws. 

[carusoam]

There are fancy new sheet metal screws to go with that... instead of pointy... they are blunted... better for your skin this way... 

Best regards,

-a-

[Guest]

48 minutes ago, 0TreeLemur said:

Thanks.  They seem to be regular sheet metal screws.   BTW- I didn't write that they took the gear doors off- I wrote that they took the gear off to paint.   It seems that anyone working down there on such a task would have ample opportunity to notice floppy gear doors??

This might help, #4 sheet metal screws into Tinnerman nuts.

Clarence

[MooneyMitch]

Have I ever mentioned how much I LOVE MS!!! 

[0TreeLemur]

Thanks everyone!   Now I have another activity to keep me "socially distant" tomorrow!

[Jerry 5TJ]

If you own a vintage Mooney you will never lack for projects. 

[RLCarter]

42 minutes ago, Jerry 5TJ said:

If you own a vintage Mooney you will never lack for projects. 

If you own a vintage Aircraft you will never lack for projects, and I'm not real sure "vintage" needs to be in the statement 

[Yetti]

Over the years various screws were probably inserted.  You have to loosen them at some times to get the rear panels to fit.   So take all them off. replace with tinnerman, check the hinge to make sure it does not need replacing.  Can buy it from Spruce and cut to length.

[Guest]

In many cases unknowing maintainers removed the gear doors, never getting the Tinnerman nuts on the screw.  Then they install all manner of larger screws trying to tighten the hinges.  If you remove the lower fuselage fairing on each side you will likely find a pile of Tinnerman nuts collected in the back corner.

Clarence

[Yetti]

6 minutes ago, M20Doc said:

In many cases unknowing maintainers removed the gear doors, never getting the Tinnerman nuts on the screw.  Then they install all manner of larger screws trying to tighten the hinges.  If you remove the lower fuselage fairing on each side you will likely find a pile of Tinnerman nuts collected in the back corner.

Clarence

ha ha the reign down of parts when you remove a panel.   A little disconcerting the first time it happens.  :-)

 

[0TreeLemur]

10 hours ago, M20Doc said:

This might help, #4 sheet metal screws into Tinnerman nuts.

Clarence

Is this version of the parts manual available online?   Both the print and pdf versions of it that I have don't show this level of detail- they just show the door on Fig. 26 with no fasteners or holes.  The parts list does list 9 ea. AN530-4R8 screws with 9 ea. A1890-4Z-1 speed nuts.  Your version of the Parts manual would have answered my question.  Thx.

[cliffy]

In reality, Tinnerman nuts should be used with TYPE B screws NOT standard sheet metal screws, It has to do with the pitch diameter of the screws. Here's what they look like-

https://www.aircraftspruce.com/catalog/hapages/trusstypeb.php

While sheet metal screws (the sharp pointy ones) can be made to work, they really aren't the correct screws

Also in observing your picture it looks like there is worn out metal above the missing screw hole. You might need some sheet metal work in that area.

Something to think about for the next annual might be to inspect, clean and repaint the nose gear push/pull rods. They look a little the worse for wear in the picture. If you remove them you will have to reset the entire gear over center torque NOT just the nose gear setting.

Edited March 22, 2020 by cliffy

[0TreeLemur]

5 minutes ago, cliffy said:

In reality, Tinnerman nuts should be used with TYPE B screws NOT standard sheet metal screws, It has to do with the pitch diameter of the screws. Here's what they look like-

https://www.aircraftspruce.com/catalog/hapages/trusstypeb.php

While sheet metal screws (the sharp pointy ones) can be made to work, they really aren't the correct screws

Also in observing your picture it looks like there is worn out metal above the missing screw hole. You might need some sheet metal work in that area.

Thanks for pointing that out.  I'll take a look at the area that seems like missing metal and see if that is real or some kind of shadow/artifact.

[MooneyMitch]

“In reality, Tinnerman nuts should be used with TYPE B screws NOT standard sheet metal screws, It has to do with the pitch diameter of the screws. Here's what they look like-“

Thank you for that.  My memory did not serve me well.  

[Guest]

3 hours ago, 0TreeLemur said:

Is this version of the parts manual available online?   Both the print and pdf versions of it that I have don't show this level of detail- they just show the door on Fig. 26 with no fasteners or holes.  The parts list does list 9 ea. AN530-4R8 screws with 9 ea. A1890-4Z-1 speed nuts.  Your version of the Parts manual would have answered my question.  Thx.

As an MSC I have access to the Mooney library, many of which I have on my iPad at home.

Clarence

[0TreeLemur]

1 minute ago, M20Doc said:

As an MSC I have access to the Mooney library, many of which I have on my iPad at home.

Clarence

Aha.  As usual, thanks for your reply! 

I did not know that you were a MSC.  Too bad you're so far away!  In another country!

-Fred

[Old Chub]

I had what M20Doc described as all different sizes of sheet metal screws installed in the nose gear door hinges.   From sheet metal screw sizes ranging from 6 to 10 I elected to go the machine screw route with nut plates.   Yes it was a pain to do all of the positions in nut plates (with countersunk rivets) but I now have number 8 machine screws in all positions and as you know the nut plates are self locking so they are now very secure.    Prior I was finding loose sheet metal screws almost every post flight.  And yes I found no Tinnerman nuts on the back side of my sheet metal screws holding the nose gear door hinges to airframe.  

 

A&P, IA, DAR 

 

 

[Guest]

21 minutes ago, Old Chub said:

I had what M20Doc described as all different sizes of sheet metal screws installed in the nose gear door hinges.   From sheet metal screw sizes ranging from 6 to 10 I elected to go the machine screw route with nut plates.   Yes it was a pain to do all of the positions in nut plates (with countersunk rivets) but I now have number 8 machine screws in all positions and as you know the nut plates are self locking so they are now very secure.    Prior I was finding loose sheet metal screws almost every post flight.  And yes I found no Tinnerman nuts on the back side of my sheet metal screws holding the nose gear door hinges to airframe.  

 

A&P, IA, DAR 

 

 

That is the method used on most of the newer models, no chance of lost Tinnerman nuts now.

Clarence 

[0TreeLemur]

UPDATE:  Today we removed the forward belly panels from LHS and RHS.  Here's what we discovered:   The piano hinges on both sides were fastened with an assortment of mostly #4 screws on both sides, of various lengths, all but one with a pointy end, and only three used Tinnerman nuts.    My co-pilot found six Tnuts unassociated with screws on the left side in the miscellaneous agglomeration of quasi-gritty and used ta be sticky substance formerly known as lubricant as she cleaned the area.   Oddly, the Tnuts on the LHS had loosened.  This indicates that either the wrong type of screws were used or the Tnuts lost their grip somehow. 

Plan of action: order new type-B screws with Tnuts and replace them all on LHS and RSH during next weekend's social-distancing at the airport.   Regular preflight now to include jiggling the nose gear doors to make sure they haven't worked loose.  Thanks to everyone for the guidance.

-Fred

[Mooneymuscle56m]

I just had and issue in the hinge itself on my long body. My MSC was able to source a new hinge from Mooney for under $100 a side. 
 

As long as I have owned the plane I have noticed a vibration in the floor,  it was getting worse then I notice one day it went away when the gear went down.  Now the vibration is slight but still there, no more adjustment in the rod linkage but has the slightest play in the connecting rod ends.  I’m going to have the rod ends replaced when I get back to my MSC.  On a better note, I think I picked up 4-5 kts tightening the nose gear doors.
 

I noticed a long body on the ramp so I went and check it out, way more sloppiness than mine ever was.  Maybe a common problem..? The other doors were composite, and my are aluminum. Serial number says our planes are 67 part.