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twitchy nosewheel on roll-out

Cervelorod

By Cervelorod
in Vintage Mooneys (pre-J models)

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Cervelorod Contributor

Cervelorod

Posted
Posted

I finished my 6th hour in the F this morning and I am still having trouble with my rollout.  The plane seems to want to drift left, and corrections send us into swerves, that have almost put us off the runway ( once )..

I changed my technique with my feet, and that seemed to help some. Hitting the numbers keeps it to a minimum, but it still is very squirrely on rollout. 

I'm sure part of it is pilot induced, but looking for any tips / techniques if you've seen this issue before.

I'm somewhat limited on CFI's in our area.  The CFI I used is a good pilot, and has flown just about everything including Mooney time, but I'm sure he is nothing like a Mooney specific CFI.  I will be looking for some Mooney specific time now that I can travel away from the home drome for training.

 

Thanks,

Rod

6341Q M20F

 

bonal Grand Master

bonal

Posted
Posted (edited)

Just a thought yesterday's landing at home winds were variable but with some local gusts just after touchdown we took a quartering tail wind gust and it weather vaned us to the right big time was able to get it under control but took a good bit of effort what were the wind conditions at the time this happened

Edited by bonal
RobertGary1 Grand Master

RobertGary1

Posted
Posted

Could be gear or overacting on the rudder. Are you holding aileron correction into the wind throughout rollout? Agreed that it's good to have everything checkout. It's also part of annual (per the mooney maint manual)

 

 

MyNameIsNobody Grand Master

MyNameIsNobody

Posted
Posted

Doubt it is you.  Should not be squirelley.  Get it check out ASAP.  If it is loose (mine was) Laser brass insert and shims work great.  Good luck.  Be careful.

Guest

Guest

Posted
Posted

Worn nose gear steering "Tee" and incorrect castor angle per SB M20-202 will make landing roll out in a Mooney exiting.

Clarence

Cervelorod Contributor

Cervelorod

Posted
  • Author
Posted

Put it on jacks and low and behold the plumb line is 3/8" behind the axle center.  The wheel is just doing what physics says it will do, try to caster around...

 

I am trying to find the actual SB to see what is included in the kit.  Sucks to find this on Sunday of a long weekend...

Thanks Everyone!!!

 

Rod

  • Like 1
Yetti Grand Master

Yetti

Posted
Posted

also if you have large feet make sure you are not hitting the brakes.  Somewhere in the pattern I think "heels on floor" "heels on floor"  and wiggle the rudder.

Guest

Guest

Posted
Posted

Put it on jacks and low and behold the plumb line is 3/8" behind the axle center.  The wheel is just doing what physics says it will do, try to caster around...

 

I am trying to find the actual SB to see what is included in the kit.  Sucks to find this on Sunday of a long weekend...

Thanks Everyone!!!

 

Rod

Check to see if the upper stop collar on the nose gear has an offset hole, sometimes they do and simply flipping it over will correct the caster angle, failing that you'll need additional spacers under the collar.

Clarence

Cervelorod Contributor

Cervelorod

Posted
  • Author
Posted

Check to see if the upper stop collar on the nose gear has an offset hole, sometimes they do and simply flipping it over will correct the caster angle, failing that you'll need additional spacers under the collar.

Clarence

M20Doc,  I can understand flipping the collar over if it has another hole a different distance from the face, but I can't see in my minds eye how adding spacers will move the axle into trail.  Caveat, I have not disassembled the shock disc assembly yet, but from the service and parts manual I can't imagine it..

Thanks!!

 

Rod

Guest

Guest

Posted
Posted

M20Doc,  I can understand flipping the collar over if it has another hole a different distance from the face, but I can't see in my minds eye how adding spacers will move the axle into trail.  Caveat, I have not disassembled the shock disc assembly yet, but from the service and parts manual I can't imagine it..

Thanks!!

 

Rod

By compressing the shock discs more, be either flipping the collar or adding shims you change the caster angle of the nose gear.

Clarence

MyNameIsNobody Grand Master

MyNameIsNobody

Posted
Posted

Worn nose gear steering "Tee" and incorrect castor angle per SB M20-202 will make landing roll out in a Mooney exiting.

Clarence

Exciting, while exiting...the runway :)

  • Like 1
Cervelorod Contributor

Cervelorod

Posted
  • Author
Posted

Took the collar off this morning and mic'ed the distance's on either side.  One side had 0.153" and the other was 0.185".  Flipped the collar over and the plumb line was centered on the axle.  Test flew it and it's a whole lot better.  It still has a little twitchiness, but it's not looking for the exit..  I wonder if moving the center of the axle 0.05" behind the plumb line will make it better.  

M20Doc, it seems like there is some variation in the collar's, what is a good value to shoot for?

Thanks to all!

Rod

 

  • Like 1
Guest

Guest

Posted
Posted

Took the collar off this morning and mic'ed the distance's on either side.  One side had 0.153" and the other was 0.185".  Flipped the collar over and the plumb line was centered on the axle.  Test flew it and it's a whole lot better.  It still has a little twitchiness, but it's not looking for the exit..  I wonder if moving the center of the axle 0.05" behind the plumb line will make it better.  

M20Doc, it seems like there is some variation in the collar's, what is a good value to shoot for?

Thanks to all!

Rod

 

Whichever combination of stop collar and or spacers gives the correct caster angle as called out in the SB or maintenance manual.

Clarence

  • 2 weeks later...
Cervelorod Contributor

Cervelorod

Posted
  • Author
Posted (edited)

Mooney emailed me the Service Bulletin, which doesn't call out a ending caster angle, just a beginning measurement and a shim if you are outside that.  We manufactured a shim, 0.120" 1.25 dia 4130 cond. N. tubing, and I finally got to test fly it today.

PERFECTION...  No darting to the left.  Can keep my heels on the floor to work the rudder and not feel as though I have to cover the brakes to keep her on the runway.

Thanks to all, especially M20Doc.

PS - the shim moved the center of the axle 1.15" behind the centerline, it had been 0.375 in front of the centerline.

sbm20-202.pdf

Edited by Cervelorod
  • Like 2
Guest

Guest

Posted
Posted

Mooney emailed me the Service Bulletin, which doesn't call out a ending caster angle, just a beginning measurement and a shim if you are outside that.  We manufactured a shim, 0.120" 1.25 dia 4130 cond. N. tubing, and I finally got to test fly it today.

PERFECTION...  No darting to the left.  Can keep my heels on the floor to work the rudder and not feel as though I have to cover the brakes to keep her on the runway.

Thanks to all, especially M20Doc.

PS - the shim moved the center of the axle 1.15" behind the centerline, it had been 0.375 in front of the centerline.

sbm20-202.pdf

You should be really pleased with how well it tracks down the runway now. And no fear of an off runway excursion.

Clarence

  • 6 months later...
Guest

Guest

Posted
Posted
2 hours ago, daver328 said:

It will make it way better.

After installing new shock discs we were really squirrelly. Read bulletin. Read Don Maxwells "Eight Second Ride." We looked at that spacer (purchased from Don Maxwell) and wondered "Just how in the world can this little spacer make a difference?" Made all the difference! 

Also, over the years Mooney has reduced the amount of torque on that vertical bolt (can't recall the specific name) ... and that also makes a difference. 

See SI M20-109 for nose bolt torque and SB M20-202 for nose gear castor angle.

Clarence

carusoam Grand Master

carusoam

Posted
Posted

Welcome aboard Electric Mike.

Keep in mind some type of work is best left for the pros.  (Legal issue) 

It may help to let people know you are a mechanic or you are working with your mechanic.

I'm glad you are here seeking guidance.

Best regards,

-a-

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