Wing bolt orientation

RVNewsletter · Post by **RVNewsletter** » Mon Jun 07, 2010 8:19 pm

The only drawing I can find in the plans regarding wing bolts is for a 7, not an "A" model. Obviously on the taildragger, having all bolts oriented from front to back is certainly not a problem. But with the gear weldments, some -- well, all four -- of the bottom bolts must be oriented back to front, right?

Also, I'm torquing the rear spar attach bolt and looking up the proper torque to use. Is this bolt a fine thread or course thread bolt and how does one distinguish the two?
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Bob Collins

cjensen · Post by **cjensen** » Mon Jun 07, 2010 8:31 pm

Even on the taildragger, at least one of the lower bolts have to go in back to front because of the gusset in front of the spar...

I'll let the "A" guys chime in on the rest of the bolts, but I have one backwards.

I believe the rear spar bolt is fine thread...I think the only course thread bolts used anywhere are Lycoming engine bolts. I can't remember any specific area where course is used in the airframe. I think anything with a 20 or less pitch is course and 24 pitch or more is fine.

Tom may be able to clarify here...

TomNativeNewYorker · Post by **TomNativeNewYorker** » Mon Jun 07, 2010 9:16 pm

cjensen wrote: I think anything with a 20 or less pitch is course and 24 pitch or more is fine.

Tom may be able to clarify here...

It all depends on the diameter of the bolt or screw. Off the top of my head a 1/4"x28 is a national fine, while the 1/4"x20 is national corse

Here is a chart off of wiki which shows the standard for NC and NF pitch for the standard diameters. http://en.wikipedia.org/wiki/Unified_Th ... esignation

Also a little snippet from wiki about the differences between NC and NF pitch '
A common misconception among people not familiar with engineering or machining is that the term coarse implies here lower quality and the term fine implies higher quality. The terms when used in reference to screw thread pitch have nothing to do with the tolerances used (degree of precision) or the amount of craftsmanship, quality, or cost. They simply refer to the size of the threads relative to the screw diameter. Coarse threads can be made accurately, or fine threads inaccurately.'

Post by **bullojm1** » Mon Jun 07, 2010 9:18 pm

Bob,

I inserted all of the bolts from the aft end of the F-704, forward. That's how its shown in the drawings. Also, pay close attention to where the washers are called out for these bolts. For some reason, I think the bottom bolts require a washer under the bolt head (and nut head). Lastly, when installing them, check that the nuts don't rest on the end of the threads of the close tolerance bolts. I needed to add a few washers to many of the bolts.

The rear spar bolt I torqued using the fine thread torque value.

RVNewsletter · Post by **RVNewsletter** » Tue Jun 08, 2010 7:40 am

bullojm1 wrote:Bob,

I inserted all of the bolts from the aft end of the F-704, forward. That's how its shown in the drawings. Also, pay close attention to where the washers are called out for these bolts. For some reason, I think the bottom bolts require a washer under the bolt head (and nut head). Lastly, when installing them, check that the nuts don't rest on the end of the threads of the close tolerance bolts. I needed to add a few washers to many of the bolts.

The rear spar bolt I torqued using the fine thread torque value.

The only drawing i could find was #11, I think, which shows a taildragger.