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  #21  
Old 05-19-2019, 07:42 AM
AlexPeterson's Avatar
AlexPeterson AlexPeterson is offline
 
Join Date: Sep 2005
Location: Maple Grove, MN
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Quote:
Originally Posted by Captain Avgas View Post
Yes, Waltís thread is the definitive thread on the nose gear. A must read. However the actual spec for the AN 5/16 close tolerance bolt is in fact .3112 min to .3117 max. And as you stated the spec for the standard AN 5/16 bolt is .309 min to .312 max. Therefore it is technically possible that a standard bolt could have a larger shank than a close tolerance bolt and therefore be a tighter fit in the hole as Colin P. discovered (post #17).
As to the OP. Iíd also be worried that his new found nose gear ďtightnessĒ is due to clamping forces. As others have stated he would be well advised to check the nose gear slop with the nut backed off. That could be enlightening. Lack of slop due only to clamping force will last for maybe only a landing or two. I canít imagine from the original video that the OPís problem could possibly be rectified simply by replacing the bolt with a new one of the same spec.
Bob, you are correct on the diameters of close tolerance bolts, not sure where I came up with the wrong ones.
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  #22  
Old 05-19-2019, 11:28 PM
Captain Avgas Captain Avgas is offline
 
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Location: Melbourne, Australia
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The excessive movement in the nose gear as shown in the video posted by the OP is indicative of metal deformation at the location where the nose gear is bolted to the engine mount. There are 3 steel items at that location that could potentially yield leading to the movement. The first is the spring steel nose leg, the second is the engine mount, and the third is the AN bolt. I am sceptical that replacing the bolt would produce a satisfactory outcome because I would be reasonably confident that the yield strength of the bolt would be considerably higher than the yield strength of either the nose leg or the engine mount. My best guess is that in this case there would be yielding/deformation at the 2 holes in the engine mount.
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  #23  
Old 05-20-2019, 07:04 AM
Alchemist Alchemist is offline
 
Join Date: Mar 2014
Location: Glasgow, KY
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Quote:
Originally Posted by AlexPeterson View Post
Thanks. There remains a concern that you may have eliminated the play by the clamping force of the bolt, and not the fit of the bolt's shank in the gear leg and the gear socket. The nut and washer in this case provide only one real function - to keep the bolt from falling out. It is not a clamping type of application. What torque value was applied to the bolt?
I will go back out today and check it again with the nut loose, I only checked it with the nut torque @140 in/lb.
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  #24  
Old 05-20-2019, 08:57 PM
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chrishalfman chrishalfman is offline
 
Join Date: Jan 2005
Location: LaVista, NE
Posts: 60
Default Not a thing, with the right stuff.

The quick version is you're going to need to install a 1st or 2nd over bolt. (Or go the tapered route as was linked earlier in the thread.) Genuine Aircraft Hardware (moderators-delete out if their name shouldn't be in here) can help you out. I made a call to the vendor, borrowed tools, and fixed mine. I mean, this person I know that has an RV...... If you need the nut tight to have the leg tight, it ain't right and it ain't tight. For long.

At about 200 hours I notices a wiggle like you have on the nose. Tightened things up can called it good. Had to mess with a main a little while later noticed when I grabbed the rear of the pant it moved up and down-ish. A lot. Granted, it's out a bit from the axis so the motion is a bit exaggerated, but it was not right. Marked the top of the leg to the gear weldment, moved the pant, took a look.... sinking feeling in your gut. The nose wheel was lose again, too. Figured out all three of my gear legs were not even close to tight. If you built your plane, it's not a big thing, just takes a little time to fix. I see your profile has CNC machining as an interest, so I wonít bore you with the details regarding someone with no machining experience (me) needed to learn. (Luckily one retired guy in our EAA chapter spend his entire career locating and machining holes in things.) I ordered NAS6605-25X (nose) and NAS6605-29Y (mains) hardware from Genuine Aircraft Hardware. (Yes, I went 2nd over on my mains. ) They have reamers, too. Just make sure to ream out your flat washers.

Why did I have that problem? Lack of builder knowledge. Ream, drill, match-drill. Same thing, right? Nope. I knew the spar/wings were close tolerance bolts. Didnít know that about the gear. Itís fixed now.

My experience showed the gear legs and bolt had almost no wear on them. The bolt had the cad plating start to wear off, but they looked amazingly ok. And they fell right out when the pressure was taken off them. The weldment holes are what got beat up. As Captain Avgas mentioned, it makes sense, since it is the softest material of the three.

Iíll get it right on my second airplane.

Hereís a link to help:
http://www.vansairforce.com/communit...ght=NAS6605-25
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-7A, 300+ hours on the Hobbs, ECi O-360 185 hp, GA200L Whirlwind prop
Anything I post on here may not be the best way, the right way, the only way, or even an accepted way to do something, but it's how I did it. Use the information accordingly.
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  #25  
Old 05-20-2019, 10:23 PM
Captain Avgas Captain Avgas is offline
 
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Yielding of the engine mount in this location is widespread on the A models. It is exacerbated by the following factors: 1. Failure to use a precision reamer during the build to ensure a true interference fit of the bolt (if you didnít need a rubber mallet to get the bolt in then you didnít do it right). 2. Continual landing on unsealed surfaces. 3. Poor take-off, landing, and taxi technique. 4. Failure to comply with SB 14 12 22. 5. Poor nose gear maintenance practices resulting in shimmy.
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  #26  
Old 05-21-2019, 06:06 AM
Alchemist Alchemist is offline
 
Join Date: Mar 2014
Location: Glasgow, KY
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Wow thanks for all the responses guys, love this forum. Iím not the builder as this is a 1998 model. The plane is very well documented and I havenít had any landing mishaps(yet) and only handed on hard surfaces but I canít speak for other owners.

I am getting some gauges to measure the hole ID of the mount and will mic the bolts to find a best fit. I will post my findings when the repair is made.
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  #27  
Old 05-21-2019, 08:17 AM
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Raymo Raymo is offline
 
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Location: Richmond Hill, GA (KLHW)
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Mine was doing the same and caused a shimmy during landing roll-out. A close tolerance bolt mostly fixed it but I know it is a temporary fix. I'll be doing the taper pin fix in the near future.
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RV-7A - Slider - N495KL - First flt 27 Jan 17
O-360-A4M w/ AFP FM-150 FI, Dual PMags, Vetterman Trombone Exh, SkyTech starter, BandC Alt (PP failed after 226 hrs)
Catto 3 blade NLE, FlightLines Interior, James cowl, plenum & intake, Anti-Splat -14 seat mod and nose gear support
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  #28  
Old 05-21-2019, 09:08 AM
Alchemist Alchemist is offline
 
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Quote:
Originally Posted by Raymo View Post
Mine was doing the same and caused a shimmy during landing roll-out. A close tolerance bolt mostly fixed it but I know it is a temporary fix. I'll be doing the taper pin fix in the near future.
I figured mine would do that with the play I found on the condition inspection but mine is smooth as butter.
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  #29  
Old 05-31-2019, 06:53 AM
Alchemist Alchemist is offline
 
Join Date: Mar 2014
Location: Glasgow, KY
Posts: 12
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I ended up going with an AN175 bolt, will monitor for any rotation and oblonging of the hole in the motor mount.

Thanks for the help guys, waiting on the AP the inspect the aircraft and hopefully I will be finally again next week!
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