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RV-14A Nose Gear Spring Nut

bkervaski

Hellloooooooo!
Testing
Just checking over everything nearing my 40 hours ...

On my nose gear the MS21045-6 nut bottoms out on the threads. The instructions say "Fully torque the nut" but it wasn't getting to the torque value before bottoming out.

Anybody else having the same issue? If so, what did you do if anything.

Seems like I may want to install an additional U-1002 and/or MS21045-6 washers. Perhaps even a new MS21045-6 lock nut.

Advice appreciated!
 
I struggled a bit with the instructions here: what purpose does the spring serve if it's fully compressed by torquing that nut?
 
I believe the nut should always bottom out. It just sets the length (tension) of the spring. This tension should be enough to keep the donuts (elastomers) snugged up (gear unloaded) without any gap between them and the elastomer pad.

As the donuts compact (get thinner) over time, the spring length increases until it no longer has enough tension to keep them snugged up, so an extra washer just decreases the spring length (increases spring tension) to compensate for the thinner donuts. Like the manual says, 3 washers are the max allowed before the donuts need to be replaced.

The spring also cushions the gear drop as it raises off the ground and counteracts the aerodynamic forces pushing the nose wheel and fairing backwards and down in flight.

I had to add a washer since with the wheel off the ground, I could lift it about 1" before I felt the contact with the elastomers, indicating they were not snugged up.

Don't know why the manual says trimming is not needed on additional washers, they still have to fit inside the slot...
 
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I believe the nut should always bottom out. It just sets the length (tension) of the spring. This tension should be enough to keep the donuts (elastomers) snugged up (gear unloaded) without any gap between them and the elastomer pad.

As the donuts compact (get thinner) over time, the spring length increases until it no longer has enough tension to keep them snugged up, so an extra washer just decreases the spring length (increases spring tension) to compensate for the thinner donuts. Like the manual says, 3 washers are the max allowed before the donuts need to be replaced.

The spring also cushions the gear drop as it raises off the ground.

I had to add a washer since with the wheel off the ground, I could lift it about 1" before I felt the contact with the elastomers, indicating they were not snugged up.

Don't know why the manual says trimming is not needed on additional washers, they still have to fit inside the slot...

Thanks for the explanation!
 
As mentioned by Jake, the reason the manual describes it as fully torquing the nut is because the desire is for the nut to bottom out on the threads to set the proper amount of spring compression.
 
First, my plane has around 150 hours. I had been having an issue with nose gear/wheel shimmy for a bit. At first, I thought is was just the wheel nut might need a tiny turn because I had just greased it right before the problem started, and on the VAF forums they had mentioned this. Tightened the nut 1 notch in the castle and put the cotter pin back in. Didn't notice much difference.

Second, I had also just put on a new nose tire, so I thought maybe it was out of round. Put back on the old tire, again very little difference.

Finally, today I was taxiing with a setting sun, and I could see my nose gear shadow. When the shimmy started I looked at the shadow and saw that it wasn't the wheel at all, but the entire nose gear assembly that was shaking. Went back to the hangar, put her in and drove around the other hangars until I could find a second person to lean on the tail so I could check the nose gear. Man did it wobble. I noticed about 1/8" to maybe 3/16" of a gap between the top of the 4 elastomers and the Elastomer Pad.

Van's says add 1 or 2 washers under the spring to tighten it up. NO MORE THAN 3 TOTAL WASHERS CAN BE USED! When it loosens up after 3 washers, then all 4 elastomers need to be replaced.
 
I wonder if Van's has improved the elastomers so they will last longer, or if replacement every 200 hours or so is going to be the norm. Perhaps the way the elastomers work, they just need to wear out that soon.
 
I wonder if Van's has improved the elastomers so they will last longer, or if replacement every 200 hours or so is going to be the norm. Perhaps the way the elastomers work, they just need to wear out that soon.

The donuts are a Mooney part, used in the main landing gear. They should have as good a life or better than in Mooneys. YMMV, but I hope mine does not. :D
 
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