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RV6-A Nose gear inspection

Honestly, I think that is a bit more than a slight. It will only get worse if left unchecked.

Many, including myself either replace the bolt on top with a close tolerance or even better go to a tapered bolt. You may also check to see if there is movement in the socket or just the bolt.
 
As noted above, that needs to be addressed ASAP or it will get worse. With that much play, you will probably need the ream oversize or go with a taper bolt. The taper bolt is the better choice, but access is more of a problem.
 
Start with the close tolerance bolt, it might fix the problem. They are a few thou larger in diameter than the standard ones. Do not try to simply clamp the bolt tight enough to keep the motion from happening - you will likely grossly over-torque the bolt.
 
ground it now

ground it now. all you need is 1) continue to beat on the bolt, 2) get some nose wheel shimmy, and you'll eventually 3) shear off the bolt. Which will lead to a bad day.

I put in a close tolerance bolt, but mine wasn't this bad. The correct reamer to fit the close tolerance bolt was absurdly expensive so I think I found a reamer on eBay. Probably won't last 100 holes, but I only needed one!

I agree the taper pin is the way to go but I don't know how you'd get the taper cut without pulling the engine. Sorry!
 
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ground it now. all you need is 1) continue to beat on the bolt, 2) get some nose wheel shimmy, and you'll eventually 3) shear off the bolt. Which will lead to a bad day.

I put in a close tolerance bolt, but mine wasn't this bad. The correct reamer to fit the close tolerance bolt was absurdly expensive so I think I found a reamer on eBay. Probably won't last 100 holes, but I only needed one!

I agree the taper pin is the way to go but I don't know how you'd get the taper cut without pulling the engine. Sorry!


+1. This is a serious issue that can be a 30 minute fix. Take care of it now.
 
Nose wheel stop flange in wrong position - THIS

could have caused your problem if in the past it had been installed wrong (probably was) --- I have seen this, just recently, during a condition inspection --- check service bulletin 14-12-22 - so easy to get it wrong, because "it looks right!"


Ron
 
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Correctly installed

The flange in the video is correctly installed. It could have have been wrong sometime earlier.
 
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Hello,

A slight rotation was noticed when checking the break out force on my nose wheel, is this normal ? All SB's have been addressed regarding
the nose gear/wheel and it has no noticeable flaws while flying or landing.

https://www.youtube.com/watch?v=NjQ8wUIXw4U

Thanks for the help,
Justin

Which SB?s were addresses and what was done? Was the nose stop flange in an incorrect orientation and then repositioned to the correct orientation? From the video it appears to be correctly oriented but you didn?t indicated what steps were taken re the SB compliance. If it was incorrectly oriented, the service bulletin calls for discarding the original hardware and replacing it. The can be no play in the nose gear. https://www.vansaircraft.com/wp-content/uploads/2019/01/sb14-12-22.pdf

The same issue could be caused by excessively bad towing methods but the most common cause is the issue addressed in 14-12-22 as ROMSIM pointed out. The important thing right now is that this needs to be addressed before further flight. Regardless of whether or not you?ve already competed the SB, the damage must be addressed. Contact the Van?s support staff for assistance on the repair.
 
Thanks for the response guys, I also got a response from the mothership and pulled the nose gear off to inspect. the washer showed signs of damage and the nyloc nut was past it's service life from typical hardware reuse. The thru bolt hole in the mount wasn't oblong and still round. The thru whole in the gear was still snug with bolt inserted.

I got new hardware per van's drawings and put it all back together and there is no rotation anymore and everything is in spec again. I marked the bolts and will monitor for any moment.

Looks like I found it just in time, thanks again guys!
 
Thanks for the response guys, I also got a response from the mothership and pulled the nose gear off to inspect. the washer showed signs of damage and the nyloc nut was past it's service life from typical hardware reuse. The thru bolt hole in the mount wasn't oblong and still round. The thru whole in the gear was still snug with bolt inserted.

I got new hardware per van's drawings and put it all back together and there is no rotation anymore and everything is in spec again. I marked the bolts and will monitor for any moment.

Looks like I found it just in time, thanks again guys!

Good! Question: was the bolt deformed/worn? If not, what was allowing the movement? Or did you replace it with a close tolerance bolt?
 
Bolt was just fine , washer and nut was degraded. I will take a pic if I didn?t throw the bolt, nut, and washer away.
 
Bolt was just fine , washer and nut was degraded. I will take a pic if I didn?t throw the bolt, nut, and washer away.

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?
 
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?

+1 to this, you need to check the play with the nut loose. On a side note, close tolerance bolts are not necessarily larger than AN bolts. When I installed my nose gear, I could feel a very slight tick of play. I had a variety of close tol. And AN bolts in that size. I measured them all with a micrometer, the AN was the largest diameter, so I used it, that eliminated the tick of play.
 
I had play in my nose gear bolt. I found that the bolt measured a little under on the threaded end allowing only one place on the bolt to load in shear instead of two. Checking bolts, I found the best way to resolve this problem is go to the next longer bolt and add one washer under the head and two under the nut. It now placed a greater part of the shank of the bolt in a press (tap in) fit. The leg now has NO play in any direction without the nut installed.
 
A close tolerance AN bolt of -5 size (which I'm going from memory is the nose gear size) is .3125/.3120 in OD. A regular -5 AN bolt will be .312/.309" OD. Doesn't sound like a lot, but it makes a large difference in this thread's subject application.

There is a lot of information that thread Walt linked earlier in this thread, please have a look. It really should be mandatory reading for any tri-gear owner/operator.

Worth mentioning is to be sure that the shank part of the bolt extends completely through the OD of the motor mount socket, and use washers as appropriate. You do not want the threads contacting the socket as they will not support shear as well.
 
A close tolerance AN bolt of -5 size (which I'm going from memory is the nose gear size) is .3125/.3120 in OD. A regular -5 AN bolt will be .312/.309" OD. Doesn't sound like a lot, but it makes a large difference in this thread's subject application.

There is a lot of information that thread Walt linked earlier in this thread, please have a look. It really should be mandatory reading for any tri-gear owner/operator.
.

Yes, Walt?s 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. I?d also be worried that his new found nose gear ?tightness? 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 can?t imagine from the original video that the OP?s problem could possibly be rectified simply by replacing the bolt with a new one of the same spec.
 
Yes, Walt?s 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. I?d also be worried that his new found nose gear ?tightness? 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 can?t imagine from the original video that the OP?s 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.
 
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.
 
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.
 
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...... :rolleyes: 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 won?t 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. :eek:) 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. Didn?t know that about the gear. It?s 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.

I?ll get it right on my second airplane. :D

Here?s a link to help:
http://www.vansairforce.com/community/showthread.php?t=24566&highlight=NAS6605-25
 
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 didn?t need a rubber mallet to get the bolt in then you didn?t 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.
 
Wow thanks for all the responses guys, love this forum. I?m not the builder as this is a 1998 model. The plane is very well documented and I haven?t had any landing mishaps(yet) and only handed on hard surfaces but I can?t 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.
 
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.
 
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. :confused:
 
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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