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Over size AN 5-20 for main gear?

bret

Well Known Member
So back in the early day of building, before I learned to look at every single detail of the plans carefully, I got ahead of my self and reamed out the landing gear bolt holes for the 5/16 bolt, I know you experienced builders are saying to your self ( No he didn't, not a 5/16 reamer ) yip thought I knew what I was doing until I read on here something about this .311 reamer, What? I go back and find out I messed up. So, this is for the main gear, I did the taper pin on the nose gear but I don't want to go through that proses inside the fuse, I am looking for an oversize bolt part number, I remember reading somewhere about specialty aircraft hardware with a part number ending in a X or Y ? .005" -.007" larger diameter to accommodate a hole that had a 5/16 reamer gone through? Thanks.
 
"X" is 1st OS, and "Y" is 2nd OS

There are other posts for this, and I recomend you search them. For the most part, you will need an NAS6605 -(length) X bolt. The X indicates first oversize (approx. 1/64") There is also a "Y", which is 1/32" O.S. The AN bolts are a little sloppier, but a nominal size AN-5 bolt would go in a .312" reamed hole. For the NAS9905-*Y bolt, you would ream to .325"-.328". Keep in mind, I am just briefing general guidelines, but the fact is, you have options. VANS likely carries some of these, as well as the usuall Big Box aviation hardware vendors.
 
Assuming you reamed carefully to 5/16 (.3125) diameter, you're really only .0015 looser than you wanted to be. That's within the tolerance band of the AN5 bolt (.309/.312"). Check with Vans, but I'd be inclined to see if a NAS6205 close-tolerance bolt would be the ticket here at .3110/.3120" diameter.
 
I called vans, they said they never heard of anyone ever reaming out a landing gear bolt to 5/16" I thought I was ok to ream a 5/16 bolt hole for a 5/16 bolt, the plans do say .311 reamer but in regular print, I didn't see it till years later on here, for a new builder like me I think it should be highlighted a little, I have seen other post on here in the past with the same mistake being made. I measure .315 at the gear mount and the bolt at .310 so I am .005 to big. all in all it is ok there is just a bout 1/8 to 1/4" play at the axle nut if the fuse is supported and you move the landing gear for and aft......the taper pin is the ticket, (did the nose gear) but that was a lot of work on the bench, cant imagine doing it inside the fuse!
 
Used standard NAS bolt and took up the gap in nose strut to make snug fit. Old AN bolt already had small ridge cut in it nearest the nut. Went thru backside of firewall. No picnic but doable.
 
Close tolerance bolts

You may want to contact...

http://www.gen-aircraft-hardware.com/

They were/are an advertiser on this site and have helped many people solve sloppy hole problems. There's lots in the archives or just give him a call. He has the bolts and reamers for close tolerance/oversize bolts and knows what you will need so they will never loosen up.

Bevan
just a very satisfied GAHco customer.
 
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I had to go with an oversized bolt on one of my main gear legs, believe it was 1/64 oversize, and the appropriate sized reamer. If you contact General Aircraft Hardware http://www.gen-aircraft-hardware.com/ they will set you up with needed bolt and reamer.

Looks like I just got beat to the punch above...

Chris
 
The metric equivalent to the 5/16 is a few thou bigger and is what i used for a better fit on my nose gear
 
The metric equivalent to the 5/16 is a few thou bigger and is what i used for a better fit on my nose gear
 
I did it, too!

Bret,

I did the same exact thing! I was sick to my stomach when I realized what I had done. Last thing I want is sloppiness in the gear leg mount from a hole that's too big for the bolt that holds it all together.

I described exactly how I fixed it, the reamer and hardware required, with lots of pictures, on my log page here:

Fixing a Problem with the Gear Leg Bolts

Good luck with this. Keep us posted on how it turns out, please. :)
 
Thanks Bruce, I wonder how many people have made our mistake, it really should be outline a little better.....
 
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