RV-6 rear spar bolt
 

Is the rear spar bolt an AN5-7 castle? Or is it something close tolerance and special?

Thanks,

-Bruce

It should just be a standard bolt with a castle nut.

I measured it it's a AN5-7, thank you!

Now that we are on this topic, when I drilled my rear spar bolts one of them fits snug but the other has the slightest indication of looseness. I thought about drilling to a larger size. I assume that they make an oversize(close tolerance) AN5 size bolt so that I do not have to step up to an AN7. Any recommendations?

CLOSE
 

Don't drill to #7 get a close bolt .

My AN5 feels lose... not sloppy, but not tight. And nothing on this wing has been easy... makes me suspicious.

Be careful with edge distance if you decide to upsize that bolt! This is one area that many of us struggled to meet edge distance with the AN5 let alone a larger bolt.

Are the close tolerance bolts AN175?

Bolt
 

Before you go to oversize try a NAS bolt in equivalent diameter to AN5. The smaller diameter AN bolts tend to be .002 to .0025 under the nominal size, the NAS should be right on the nominal size, ie .3125.
For those that haven't drilled this fitting yet:
drill a small pilot hole
drill with a 1/64" undersize drill bit in new or perfect condition.
Buy a quality straight flute reamer slightly under the nominal size( ex .311 reamer.
Use some kind of drill guide to final ream, even a block of hardwood with a sguare tight hole.

I am not an RV builder but a machinist in a previous life.
MSC Supply is a good source for reamers.

Spar
 

mxcdirect.com is the source for reamers. They have .310 and .311 diameter. They also have adjustable reamers.
My preference is high speed steel, straight flute reamer/