[vas4vans]

[moderator - I didn't think this was that specific to the RV-10 but feel free to move it to the RV-10 group if is more appropriate)

I've had a -10 for about 2 years and the ball has always been centered in cruise. I did install the Aerosport Rudder Trim mod about a year ago to maintain tension on the rudder pedals on the ground so I didn't have to put on the gust lock for low to moderate winds.

Starting about 6-7 weeks ago, I've had this strange situation where there is a significant yaw to the left in cruise on some flights - about half the ball is off to the right so it needs constant right rudder once it happens. Out of the 15+ flights that I have done since then, it has happened on only 3-4 flights (quite a few of those flights were local flights at fairly low speeds).

I initially thought it might be a problem with the rudder trim so I took it off completely about a week ago but the problem occurred again last weekend. I flew to a formation clinic at KVIS (from KRHV), did a few flights as part of the clinic and flew someone back to KMRY and the problem didn't show up but then it showed up again on the last short leg from KMRY to KRHV (about 17 min). It appears that it may be correlated to a higher IAS/TAS but I can't be sure.

The range of motion of the rudder on the ground seems fine and there don't appear to be any impediments to smooth movement. An A&P friend suggested it may be something aerodynamic - maybe a fairing coming slightly loose at high cruise speeds so on Wednesday I went over the airplane with a fine toothcomb but all panels and fairings seem to be snug and no fasteners appear to be missing. I did a test flight with a wing mounted 360 camera to capture anything interesting but the problem did not recur (perhaps I did not fly fast enough).

The EFIS photo is from an earlier flight when it occurred. On the last flight when the problem occurred (KMRY-KRHV), unlike on other flights when it happened, it was very obvious when it happened - I felt the yaw and had to put in right rudder in cruise. I have also attached a screenshot from an app called FlySto (I uploaded my flight/engine logs to it) right after the issue showed up and it shows an IAS at the top of the green.

Also, once the problem happens, it doesn't seem to go away until power is reduced quite a bit for the descent.

Any ideas of what might be causing this yaw or steps I might take to help figure it out.

Thanks,
Vas

 

[rvbuilder2002]

[moderator - I didn't think this was that specific to the RV-10 but feel free to move it to the RV-10 group if is more appropriate)

I've had a -10 for about 2 years and the ball has always been centered in cruise. I did install the Aerosport Rudder Trim mod about a year ago to maintain tension on the rudder pedals on the ground so I didn't have to put on the gust lock for low to moderate winds.

Starting about 6-7 weeks ago, I've had this strange situation where there is a significant yaw to the left in cruise on some flights - about half the ball is off to the right so it needs constant right rudder once it happens. Out of the 15+ flights that I have done since then, it has happened on only 3-4 flights (quite a few of those flights were local flights at fairly low speeds).

I initially thought it might be a problem with the rudder trim so I took it off completely about a week ago but the problem occurred again last weekend. I flew to a formation clinic at KVIS (from KRHV), did a few flights as part of the clinic and flew someone back to KMRY and the problem didn't show up but then it showed up again on the last short leg from KMRY to KRHV (about 17 min). It appears that it may be correlated to a higher IAS/TAS but I can't be sure.

The range of motion of the rudder on the ground seems fine and there don't appear to be any impediments to smooth movement. An A&P friend suggested it may be something aerodynamic - maybe a fairing coming slightly loose at high cruise speeds so on Wednesday I went over the airplane with a fine toothcomb but all panels and fairings seem to be snug and no fasteners appear to be missing. I did a test flight with a wing mounted 360 camera to capture anything interesting but the problem did not recur (perhaps I did not fly fast enough).

The EFIS photo is from an earlier flight when it occurred. On the last flight when the problem occurred (KMRY-KRHV), unlike on other flights when it happened, it was very obvious when it happened - I felt the yaw and had to put in right rudder in cruise. I have also attached a screenshot from an app called FlySto (I uploaded my flight/engine logs to it) right after the issue showed up and it shows an IAS at the top of the green.

Also, once the problem happens, it doesn't seem to go away until power is reduced quite a bit for the descent.

Any ideas of what might be causing this yaw or steps I might take to help figure it out.

Thanks,
Vas

Breakout force on the nose wheel steering has gotten below the specified value.
Airplane hits a little turbulence bump, which yaws the aircraft,
and then the nose wheel swings slightly off center, because the breakout is so low.
From that point on the ball will be out of center because of the influence of the nose wheel fairing being misaligned.

 

[BobTurner]

Breakout force on the nose wheel steering has gotten below the specified value.
Airplane hits a little turbulence bump, which yaws the aircraft,
and then the nose wheel swings slightly off center, because the breakout is so low.
From that point on the ball will be out of center because of the influence of the nose wheel fairing being misaligned.

+1. This happened to me once, and rvbuilder is spot on.
Vas, if you don’t know how to test or tighten this up, let me know.

Bob

 

[Carl Froehlich]

In addtion to the nose wheel (and nose wheel pant), I suggest you look at the main gear wheel pants and leg fairings. If they can move then it will move the ball out.

Carl

 

[vas4vans]

Thanks @rvbuilder2002 and @BobTurner ! That seems to make a lot of sense given the symptoms. Bob, I'm not clear on how to test or adjust it so I will DM you.

@Carl Froehlich I did check all the wheel and leg fairings and they seemed to be quite tight.

Vas

 

[Mel]

I agree with Scott & Bob. Seen this several times. Not that unusual.

 

[vas4vans]

I checked the breakout force on the nose wheel and sure enough, it was only 13 pounds vs. the recommended 27 pounds. I tightened the castellated nut (MS21025-24) at the bottom of the spindle by only about 20-25 degrees and I was able to get the correct breakout force.

But the issue I now have is that the holes in the spindle no longer line up with the "slots" in the castellated nut. The slots are 60 degrees apart (six of them around the edge of the nut) and the old holes in the spindle are between two slots.

@BobTurner has been providing some guidance but I wanted to get some additional ideas.

A few questions:
- Does anyone know of thin washers of the same inner and outer diameter as the washer between the castellated nut and the Belleville washers (5710-243-060) that I could put in between the nut and the existing 5710-243-060 washer so that I could use the same holes as before for the cotter pin. Would it make sense to add another 5710-243-060 washer but I suspect it may be too thick to achieve the desired end result?

-If that is not possible (I have looked in lots of places online and have been unable to find a suitable washer), is it ok to drill another set of holes through the spindle for the cotter key?

-Or does it make sense to get two new Belleville washers? Is it possible that the original ones have some wear and tear which is why I had the issue in the first place.

Is there any other way to accomplish what needs to be done to get the castellated nut secure with the cotter key with the increased break out force.

Thanks,

Vas

 

[Richard Connell]

Others with extra experience may chime in but I’ve done it twice and just go the extra degrees as necessary to reuse the next existing hole.
IMHO this isnt a precision instrument, nor is it being measured by a precision instrument. My pull scales are decidedly agricultural.
Too loose has obvious issues. Marginally too tight has yielded no discernible issues for me. It loosens up soon enough.
In time I imagine the Belleville washers will need replacement when there is no more tightening to be done.

While you have the wheel off the ground take up any slack in the gear leg rubber donuts too.

 

[rvbuilder2002]

Others with extra experience may chime in but I’ve done it twice and just go the extra degrees as necessary to reuse the next existing hole.
IMHO this isnt a precision instrument, nor is it being measured by a precision instrument. My pull scales are decidedly agricultural.
Too loose has obvious issues. Marginally too tight has yielded no discernible issues for me. It loosens up soon enough.
In time I imagine the Belleville washers will need replacement when there is no more tightening to be done.

While you have the wheel off the ground take up any slack in the gear leg rubber donuts too.

It is ok to drill additional holes for installation of the cotter pin at a different position.
It is common for the friction to loosen after the initial adjustment. Once it has been readjusted it usually doesn’t change much.
Sticking close to the recommended value is a good idea.
Too loose and it can cause shimmy and the problem you saw. Too tight and you will end up wearing brakes out faster.

 

[Tim Lewis]

But the issue I now have is that the holes in the spindle no longer line up with the "slots" in the castellated nut. The slots are 60 degrees apart (six of them around the edge of the nut) and the old holes in the spindle are between two slots.

I bought an extra flat washer from Van's, then sanded it down (belt sander) until It had the proper thickness to let the cotter pin slots in the castellated nut match up with the holes already drilled in the nose gear. I went this route after being unsuccessful in drilling an additional hole in the nose gear leg.

 

[larrynew]

I checked the breakout force on the nose wheel and sure enough, it was only 13 pounds vs. the recommended 27 pounds. I tightened the castellated nut (MS21025-24) at the bottom of the spindle by only about 20-25 degrees and I was able to get the correct breakout force.

But the issue I now have is that the holes in the spindle no longer line up with the "slots" in the castellated nut. The slots are 60 degrees apart (six of them around the edge of the nut) and the old holes in the spindle are between two slots.

@BobTurner has been providing some guidance but I wanted to get some additional ideas.

A few questions:
- Does anyone know of thin washers of the same inner and outer diameter as the washer between the castellated nut and the Belleville washers (5710-243-060) that I could put in between the nut and the existing 5710-243-060 washer so that I could use the same holes as before for the cotter pin. Would it make sense to add another 5710-243-060 washer but I suspect it may be too thick to achieve the desired end result?

-If that is not possible (I have looked in lots of places online and have been unable to find a suitable washer), is it ok to drill another set of holes through the spindle for the cotter key?

-Or does it make sense to get two new Belleville washers? Is it possible that the original ones have some wear and tear which is why I had the issue in the first place.

Is there any other way to accomplish what needs to be done to get the castellated nut secure with the cotter key with the increased break out force.

Thanks,

Vas

I know of 2 RV-10s that had the Belleville washers installed incorrectly. Ask me now I know about one! They were nested instead of opposing. It's shown clearly on the plans. It made keeping the breakout force difficult. I discovered mine early in Phase 1 when I had the same yaw problem as the OP. The other was not discovered until repairing a friend's nose wheel. He also had a problem keeping the breakout force.

 

[tom_AZ]

I bought an extra flat washer from Van's, then sanded it down (belt sander) until It had the proper thickness to let the cotter pin slots in the castellated nut match up with the holes already drilled in the nose gear. I went this route after being unsuccessful in drilling an additional hole in the nose gear leg.

I took a similar approach, but wasn’t convinced that I could do a good enough job with a sander.

I ordered TWO washers from Van’s, in case things didn’t go perfectly the first time. A neighbor has a surface grinder in his machine shop. I don’t recall the specifics, but think breakout force was something like 18 using one slot and 35 or so at the next one. I used thread pitch to guesstimate how many thousandths would need to be removed to get me to 26 lbs at the slot with the higher breakout force on the stock washer. I took off a little less than the guesstimate to start, then fine tuned it with a second run. I would think that most local machine shops would have a surface grinder and be able to perform this for you if you supply the washer.

 

[Cptnmat]

Found on my belly camera during phase I testing to Vne. Adjusted the breakout force and all is good. Drilled a second hole for fine adjustments

 

[rvanstory]

Others with extra experience may chime in but I’ve done it twice and just go the extra degrees as necessary to reuse the next existing hole.
IMHO this isnt a precision instrument, nor is it being measured by a precision instrument. My pull scales are decidedly agricultural.
Too loose has obvious issues. Marginally too tight has yielded no discernible issues for me. It loosens up soon enough.
In time I imagine the Belleville washers will need replacement when there is no more tightening to be done.

While you have the wheel off the ground take up any slack in the gear leg rubber donuts too.

First, yes it's ok to drill and extra hole for cotter pin where needed. I would do it exactly midway between existing holes, not right next to them. Second, you can have quite a bit more tension than the 26 lbs listed. If I recall, my force measures about 35 lbs and it works great. As long as your nose gear will swivel smoothly on the ground while taxiing, it should be fine. I have both situations, higher than listed break out force plus I had to drill a hole to get cotter pin in. Another thing is that I had to adjust a couple of times after 1st flight. But once "settled-in" my break out force has been good for 3 years now.

 

[rockyfatcat]

AC 43-13-1A/2B recommends torquing the castellated nut to minimum torque plus run on friction. Check for cotter pin hole alignment and continue tightening till the hole lines up, or to the maximum torque.

After that they recommend exchanging washers or nuts.

I like the idea of adjusting the thickness of the washer over drilling new holes

 

[rocketman1988]

AC 43-13-1A/2B recommends torquing the castellated nut to minimum torque plus run on friction. Check for cotter pin hole alignment and continue tightening till the hole lines up, or to the maximum torque.

After that they recommend exchanging washers or nuts.

I like the idea of adjusting the thickness of the washer over drilling new holes

That may not apply to the nose gear nut due to the belleville washers, which are not flat. There is no issue drilling new holes for the cotter pins; just use common sense and do not drill them close to the original holes.

I have had to reset my nose gear once, so far, in three years and I made it a bit tighter at 30 lbs. works great.

 

[rvbuilder2002]

AC 43-13-1A/2B recommends torquing the castellated nut to minimum torque plus run on friction. Check for cotter pin hole alignment and continue tightening till the hole lines up, or to the maximum torque.

After that they recommend exchanging washers or nuts.

I like the idea of adjusting the thickness of the washer over drilling new holes

Not relevant in the case of RV nose gear forks.