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Posted

Just finished reinstalling all my belly panels after annual.  Next year I’m just going throw away all the existing sheet metal screws and tinnerman nuts on the front panel and the panels under the exhaust & fuel pump.  All the screws are different and the nuts are worn.

Heres the problem, the manual says use AN530-8R8 screws but the head on those sits much higher (like pimples) than the existing ones which look like pan head or truss head from my brief research.  What is the correct head type?  Do I just accept that what Spruce says is AN530-8R8 with a very round head is what is supposed to be in there?

Thanks!

Posted
50 minutes ago, Ragsf15e said:

Just finished reinstalling all my belly panels after annual.  Next year I’m just going throw away all the existing sheet metal screws and tinnerman nuts on the front panel and the panels under the exhaust & fuel pump.  All the screws are different and the nuts are worn.

Heres the problem, the manual says use AN530-8R8 screws but the head on those sits much higher (like pimples) than the existing ones which look like pan head or truss head from my brief research.  What is the correct head type?  Do I just accept that what Spruce says is AN530-8R8 with a very round head is what is supposed to be in there?

Thanks!

Followed the same path just a few days ago and thought that the AN530-8R8 don't look like they offer enough contact area.  So, I'm wrestling with the same issue and today ordered some truss head blunt end (type B ) sheet metal screws:  8X1/2-B-TR-PH.  Should have them by Saturday.

  • Like 1
Posted
3 minutes ago, 0TreeLemur said:

Followed the same path just a few days ago and thought that the AN530-8R8 don't look like they offer enough contact area.  So, I'm wrestling with the same issue and today ordered some truss head blunt end (type B ) sheet metal screws:  8X1/2-B-TR-PH.  Should have them by Saturday.

Interesting.  I think I’ll wait until you get yours and see.  Do you mind posting a picture?

Posted
Just now, Ragsf15e said:

Interesting.  I think I’ll wait until you get yours and see.  Do you mind posting a picture?

Will do.

The machine screws and speed nuts I ordered Monday arrived today.  Screws: AN526-1032R8 cadmium plated pan head look great.   The speed nuts: A1787-10Z1D, don't seem to want to accept #10 machine screws, at least by hand.

 

Posted
17 minutes ago, 0TreeLemur said:

Followed the same path just a few days ago and thought that the AN530-8R8 don't look like they offer enough contact area.  So, I'm wrestling with the same issue and today ordered some truss head blunt end (type B ) sheet metal screws:  8X1/2-B-TR-PH.  Should have them by Saturday.

I think you are on the right track. The truss heads just look better. Type B have a different thread pitch than the more common Type A and Tinnermans are really designed for Type B. Actually, in some locations the length is the most important parameter (after size, of course) because a too-long screw can interfere with controls and such. I prefer stainless though some fret about the fact that stainless and aluminum can corrode. But the area of the aluminum anode is so much greater than the area of the screw cathode that there isn't really a problem.

Skip

  • Like 2
Posted
58 minutes ago, 0TreeLemur said:

Will do.

The machine screws and speed nuts I ordered Monday arrived today.  Screws: AN526-1032R8 cadmium plated pan head look great.   The speed nuts: A1787-10Z1D, don't seem to want to accept #10 machine screws, at least by hand.

 

I was confused by the end of your post… aren’t all the screws that use tinnerman (“speed nuts”) #8?  And aren’t they only the sheet metal screws, not machine screws?

On my airplane everything aft of the panel just behind the nose gear has machine screws and the nuts are “welded” into place already in the frame.  Those machine screw panels go in much easier.  The ones in the front with the #8 sheet metal screws and tinnermans are a PIA.

And that begs the question about why they switched screw types on the different belly panels?

  • Like 1
Posted

On our '67 C, speed nuts are used on the belly for machine screws as well.  From a product description:

"These speed nuts are made of stamped spring steel and are meant for spaces with minimal clearance. The design is for a quick application and removal making the nuts reusable. They act as both a lock washer and nut so can generally eliminate the need for lock washers and can be used with either sheet metal or machine screws."

Getting machine screws started in new ones requires a fair bit of force into the nut.  More than I can do by hand at my desk.    I'm thinking once I clip them in place I'll be able to get the machine screws in.

The proper question in the case of our C might be: How long did the welded nuts last, and in which decade were they drilled out and replaced with speed nuts?


 

  • Like 1
Posted

My 65C

Had the six or so 8-32 screws…. That one day became 10-32 screws…. :)
 

Then all the pointy sheet metal screws got replaced with the snub nosed variety… my skin healed after that…. :)

The Tinnermans all got replaced one at a time….

The hard ones to find are for the dog house… they are tiny… probably #6 sized…(?)

Tinnermans wear out slowly and lose their springiness…. And ability to hold a screw in place…. Real easy to replace…

 

Pp thoughts,

-a-

  • Like 1
Posted
12 hours ago, Ragsf15e said:

 aren’t all the screws that use tinnerman (“speed nuts”) #8? 

 

Didn't answer this part- our C has a bunch of #10 machine screws that use speed nuts.

  • Like 1
Posted

@Ragsf15e I'm learning a bit more.  Called my favorite A&P/IA who unfortunately has his shop 100 miles from me.   The No. 10 speed nuts that I brought from AS (A1787-10Z1D) he calls PK nuts, after the manufacturer, and are designed only for No. 10 sheet metal screws.   Yes, they will work for No. 8 machine screws, but sometimes won't tighten up, especially after some time in service.  That explains why my No. 10 machine screws won't fit them.

Since the belly skin on our C is held on by a mish-mash of machine and sheet metal screws, I'm looking for consistency.   What that looks like I don't know yet.  Gotta spend some time this weekend doing a stock take of the sit.

WRT Fig. 15 of the parts manual, my problem stems from skin panel #13, which specifies 40 ea.  AN526-1032R8 machine screws but does not specify the corresponding "other" fastener (nut).   My a/c has a bad nut on that panel.  What is it?   I'll take a photo next time I'm at the hangar hopefully this weekend.

Thx.

Posted

Mooney must have owned a screw manufacturing company, they seem to have used almost ever type of screw ever designed. #8x1/2 PK or sheet metal screws for the exhaust coves, #8x1/2 PK and AN507-632R8 for the first belly panel, AN526-1032R8 for the second, third and flap cover, AN507-832R8 for flush panels, #4 PK for wing root fairing, AN526-832R8 for bumpy panels.  There are likely some I’m missing.

Clarence

 

Posted
1 hour ago, M20Doc said:

Mooney must have owned a screw manufacturing company, they seem to have used almost ever type of screw ever designed. #8x1/2 PK or sheet metal screws for the exhaust coves, #8x1/2 PK and AN507-632R8 for the first belly panel, AN526-1032R8 for the second, third and flap cover, AN507-832R8 for flush panels, #4 PK for wing root fairing, AN526-832R8 for bumpy panels.  There are likely some I’m missing.

Clarence

 

My problem is the #8x1/2 sheet metal screws for exhaust and other forward panels… the manual part number corresponds to a round head which doesn’t look like the ones on the airplane.  The airplane ones look more like truss heads…

Posted
3 hours ago, 0TreeLemur said:

@Ragsf15e I'm learning a bit more.  Called my favorite A&P/IA who unfortunately has his shop 100 miles from me.   The No. 10 speed nuts that I brought from AS (A1787-10Z1D) he calls PK nuts, after the manufacturer, and are designed only for No. 10 sheet metal screws.   Yes, they will work for No. 8 machine screws, but sometimes won't tighten up, especially after some time in service.  That explains why my No. 10 machine screws won't fit them.

Since the belly skin on our C is held on by a mish-mash of machine and sheet metal screws, I'm looking for consistency.   What that looks like I don't know yet.  Gotta spend some time this weekend doing a stock take of the sit.

WRT Fig. 15 of the parts manual, my problem stems from skin panel #13, which specifies 40 ea.  AN526-1032R8 machine screws but does not specify the corresponding "other" fastener (nut).   My a/c has a bad nut on that panel.  What is it?   I'll take a photo next time I'm at the hangar hopefully this weekend.

Thx.

Yeah that’s tough.  Mine is a 68.  All the machine screws have nuts “welded” to the frame above the panel and they screw right in.  The sheet metal screws in the forward section and the tinnerman nuts are a different story.

Posted
1 hour ago, Ragsf15e said:

My problem is the #8x1/2 sheet metal screws for exhaust and other forward panels… the manual part number corresponds to a round head which doesn’t look like the ones on the airplane.  The airplane ones look more like truss heads…

That’s the AN 530 pan head screw.  Most have been changed to 8Rx1/2 Truss head PK screws.  Available from Spruce.

 

136B45A1-92EC-4C9C-9857-74112D2D39D4.jpeg

Posted
1 minute ago, M20Doc said:

That’s the AN 530 pan head screw.  Most have been changed to 8Rx1/2 Truss head PK screws.  Available from Spruce.

 

136B45A1-92EC-4C9C-9857-74112D2D39D4.jpeg

Yeah that’s exactly where I was in the manual and I ordered those screws, exact part number, from spruce.  They don’t look right. I’m gonna try truss head, I think you’re right about that.  Actually I’m gonna wait and see a picture of the truss heads from @0TreeLemur when his arrive and go from there.

Posted

The AN530 should be a “B” type. Spruce sells a truss head ”B” type.  A steel screw will out last the stainless steel version.

796A15C1-964E-4468-8496-13487B31A680.jpeg

Posted
On 1/21/2022 at 7:26 PM, Ragsf15e said:

Yeah that’s tough.  Mine is a 68.  All the machine screws have nuts “welded” to the frame above the panel and they screw right in.  The sheet metal screws in the forward section and the tinnerman nuts are a different story.

I'm going to try running a #10x32  tap into those two messed up welded nuts above the third belly panel tomorrow and get them to work right again.  With luck....

  • Like 2
Posted
On 1/21/2022 at 9:57 AM, 0TreeLemur said:

Didn't answer this part- our C has a bunch of #10 machine screws that use speed nuts.

O’Tree,

Look close at what you have…

The machine screws go into a threaded hole, held in place with rivets….

The sheet metal screws go into Tinnermans, speed nuts, whatever name we are using today….

 

It is important to match the threads… the machine screws are a fine thread… too fine to match the Tinnermans….

Look close… to be sure of what you have…

 

It wouldn’t be normal to use a machine screw with the Tinnermans….  The holding strength would be unknown…

 

Its possible the wrong hardware got used along the way… this happens a lot over the decades…

 

PP thoughts only, not a mechanic…

-a-

Posted

What are these called?  I cannot find them on AS.  They seem like a captured U-nut, but those search terms produce no results.   Someone mixed sizes on my a/c, interspersing a few No. 8's in with the No. 10's.    Grrrrr. 

Source recomm. appreciated. 

Thx.  Fred

 

U-nut1.jpg

U-nut2.jpg

Posted
3 minutes ago, 0TreeLemur said:

What are these called?  I cannot find them on AS.  They seem like a captured U-nut, but those search terms produce no results.   Someone mixed sizes on my a/c, interspersing a few No. 8's in with the No. 10's.    Grrrrr. 

Source recomm. appreciated. 

Thx.  Fred

 

U-nut1.jpg

U-nut2.jpg


Hmmmmm…..

Lets see if @M20Doc is familiar with Tinnermans for machine screws….   :)
 

They may be in a lot of modern Mooneys….(?)

Best regards,

-a-

Posted
1 hour ago, 0TreeLemur said:

What are these called?  I cannot find them on AS.  They seem like a captured U-nut, but those search terms produce no results.   Someone mixed sizes on my a/c, interspersing a few No. 8's in with the No. 10's.    Grrrrr. 

Source recomm. appreciated. 

Thx.  Fred

 

U-nut1.jpg

U-nut2.jpg

Oh jeez, I don’t have those.  Just the regular tinnerman for the #8 sheet metal screws.  
How did the truss heads look?

Posted
1 hour ago, Ragsf15e said:

Oh jeez, I don’t have those.  Just the regular tinnerman for the #8 sheet metal screws.  
How did the truss heads look?

The truss head screws weren't in the package- just realized that.   I'll have to look into that.  I must have another package coming tomorrow.  

edit-

Just looked at my orders, should be here tomorrow.

Posted
6 hours ago, 47U said:

Search the term ‘clipnut’ on AS… 

image.thumb.png.cf713f55bc28d94a1a514139b9d46bd0.png

From Spruce or Monroe Aerospace.

Clarence

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