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Nose wheel fairing induced yaw?

Moshonsk

Member
Just started flying my new RV-10 and had a very disconcerting experience today. First flight was excellent and as I was in engine break in and first flight mode I flew it without the wheel pants. Everything was good with the ball perfectly centred throughout the flight. Today, after installing the wheel pants, I went up again. Everything was good on climbout and it accelerated nicely almost 15 knots faster than without the pants. I was happy because the ball stayed nicely centred and all seemed well.
About 20 minutes into the flight I hit a bit of turbulence and then after a bit of bouncing and yawing I found I needed a fair bit of left rudder to keep the ball centred. Feet off the pedals the ball was now about halfway out of centre. Throughout the rest of the flight with all power settings and airspeeds I needed left rudder to keep the ball centred.
I figured I had either lost a wheel pant or the nosewheel had somehow cocked itself off centre and induced some yaw on the airplane. After I landed all fairings were present and accounted for and if the nose had cocked off centre it would have straightened itself on landing so there was no way to know there.
Has anyone experienced this? How do you correct it? More tension on the big nut or less? How do you fix it in the air? I'm assuming some aggressive rudder to straighten the fairing out.
Or is it something other than that?
 
There is a specification for the breakout force on the nosewheel - IIRC around 25 pounds.

They tend to loosen up after a few hours: I had the same symptoms on 14A soon after installing the wheel fairings.

Paradoxically, be sure the grease the belleville washers, then set the breakout force. Important step according to my guru on the topic.
 
Tighten

Moshonsk;1613480 Has anyone experienced this? How do you correct it? More tension on the big nut or less? How do you fix it in the air? I'm assuming some aggressive rudder to straighten the fairing out. Or is it something other than that?[/QUOTE said:
Tighten. I don’t recall exactly but somewhere around 27 pound breakout force measured from about the mid point . Sounds counterintuitive but I’m betting it isn’t tight enough.

Regards,
Doug
 
Also important - be sure the belleville washers are correctly oriented - the two together basically form a convex "flying saucer" shape.
 
I had a similar experience testing an Rv-10. As we approached VNE I felt a change in yaw. It now needed rudder to keep straight in the cruise whereas before it didn’t. We did a quick touch and go and it went back to normal.
Readjusted the breakout on the nose wheel and it didn’t reoccur.

Regards

Peter
 
In my experience, if you lift the nose off during T/O with any amount of yawing and the breakout force is correct, the wheel will stay in that slightly turned postion and force yawing. A good stab on the opposite rudder pedal in flight will often move it back to center. When the Break out force is too weak, usually the ball stays out a certain amount and cannot be moved back with forces on the rudder, as it is the props slipstream that keeps it in a certain turned position (I think it is always turned to the right, moving the ball to the left). You need a high enough resistance to keep the nose gear from being influenced by the prop's slipstream.

First flight is too early to tell if the ball will be centered or not. Need to learn your plane's quirks and behaviors. Also, breakout force is adjusted with a fish scale following the manual's guidance and specs. DO NOT loosen or tighten based upon flight experience or opinions on the internet. Behavior will tell you something may not be right, but the follow on is to perform the proper adjustment routine. The B/O force will need to be re-adjusted at least twice in the first 100 hours, so good to know the signs.

Larry
 
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Yes thanks for that. This wasn't the first flight. The first flight was without pants or fairings and everything was good with the ball nicely centred.
As I had stated this was the second flight and the first flight with the pants and fairings. The ball was nicely centred for the first 10 minutes into the flight and did not go out until we accelerated through about 140 indicated and hit some turbulence. In hindsight I guess I'm lucky it happened that way or I would have assumed that there was something wrong with my pant alignment if it did it immediately on liftoff.
I was surprised at how common this seems and yet there is not much mention of it online. My 2 friends with RV-9's had never even heard of that happening.
Retorquing the nut is an easy adjustment and I figured I would have to do it at some point but didn't think it would be several iterations as it works itself in but iguess it's all part of the process.
Thanks to all who took the time to offer their advice.
 
Has anyone experienced this? How do you correct it? More tension on the big nut or less?

I found tension on nose wheel after 1st flight down to less than 11 lbs of tension. Spec is 25 (IIRC), but I could get 21 at one stop of castle nut, and around 60 at the next stop. Had to drill and extra hole in nose gear tube in between. Ended up close to 40 lbs of pressure. Works great now. Even at higher than spec, nose wheel turns freely when pulling with tow bar.
 
Yes thanks for that. This wasn't the first flight. The first flight was without pants or fairings and everything was good with the ball nicely centred.
As I had stated this was the second flight and the first flight with the pants and fairings. The ball was nicely centred for the first 10 minutes into the flight and did not go out until we accelerated through about 140 indicated and hit some turbulence. In hindsight I guess I'm lucky it happened that way or I would have assumed that there was something wrong with my pant alignment if it did it immediately on liftoff.
I was surprised at how common this seems and yet there is not much mention of it online. My 2 friends with RV-9's had never even heard of that happening.
Retorquing the nut is an easy adjustment and I figured I would have to do it at some point but didn't think it would be several iterations as it works itself in but iguess it's all part of the process.
Thanks to all who took the time to offer their advice.

Let us know if retorquing will fix this or not. If it doesn't then perhaps your gear leg fearing or the wheel fearing would be the cause.
Keep in mind that this type of misalignment will show themselves more at higher speed and they increase as the speed increases.
 
Did the retorque but have yet to fly. As others have said the torque 'as found' after a couple flights had indeed dropped down to only around 11 pounds I guess as the setup wears in. Ended up retorquing to around 34 to catch the nex t available cotter pin location. Didn't want to redrill the shaft at this point as I'm sure I will be retorquing more than one more time.

I'm confident the alignment of the pants is good as we flew with the ball nicely centred for the first 15 minutes of the last flight before the Nose wheel abruptly went over.

On a related note I found with $90 worth of avgas in the baggage compartment and $240 worth on the tail tiedown I could easily hold the Nose wheel off the ground to make the adjustments.
 

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