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So my new bird likes to "dart" on landing rollout.  It does not have SB M20-202 applied, so I know there's some improvement available there.  Two things I notice:

1) The discs on the nose have a date code of 1968. :o

2) When someone works the rudder pedals I can see the sleeve of the steering horn moving independently of the arm it goes on (rotates and has slop on the outer end; looks like it can move about 1/2" each way where the pushrod attaches).

My A&P wants to put in the LASAR oversized bushing (LASKIT122A) and the spacer for SB M20-202.  I'm guessing he's also going to try to shim the horn back to spec on the arm.  So my questions are: Will that be sufficient?  Do I actually need the bushing?  Should I replace the horn and arm entirely?

I will be replacing the discs.  The ones on it might still meet spec (highly doubtful), but since he'll have to pull everything apart anyway I think it's worthwhile to replace them now.

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Look for a document by DMax called the eight second ride...

it details what you are describing.

Anything causing looseness in the steering, is bad... it is typically wear related...

Lasar has the method of curing the wear...

If you follow the SB, you will get the intended result.

old donuts don’t usually affect steering, but there may be an un-wanted change of geometry that goes with that...

There is a maintenance procedure to tell you about the donut’s compression health if you want a second opinion...

 

Reworking the old parts, puts them back in spec...

Buying new parts, they’re in spec already...

 

Check price and availability of the new parts... then decide...

You might find a good answer,...

But, you may also find new planes are expensive...

New parts and new planes all come from the same resource and are priced accordingly...  it just costs so much to have a company that builds this stuff...

PP thoughts only, not a mechanic...

Best regards,

-a-

 

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The 8 second ride, Don Maxwell has a good article on it if you haven’t seen it

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Haha, yeah.  Sage advice, Anthony. :)

I have seen that article from DMax.  It sounds pretty close to what I'm seeing.

Actually, I should probably just call DMax and discuss it...  Duh...

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OK, spoke to Don himself.  I probably just need the SB M20-202 spacer and new pucks.  The rest should be serviceable as-is, so I'll hold off on the oversized bushing or steering horn unless we get everything apart and find it's necessary.

Thanks!

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I installed a LASAR overhauled steering horn with their “hardware package” and all of the play disappeared in my steering- I don’t think they shim the horn- just an oversized bushing. I’m curious what kind of tire pressures you are running well...

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One more item to check while in there might be the 4 bushings

just aft of the bottom of the firewall that the rudder pedals rotate in.

They are AN3 bolts and if they are loose lots of play in the pedals is noted.

Can't see all 4 at one time but take the small firewall panel at the bottom of 

the firewall off  and you can see two of them (one each side). Move the pedals 

to check for play. I'll bet they have never been looked at for wear (or ever been lubricated).

In order to tighten

the two outboard ones you have to drill a 1/2" hole directly above them on the floor inside

up by the pedals. Don't worry its a non structural panel. Cover hole with silver high speed tape

when done. You'll need a ground down 3/8" box wrench to get in the hole and get around the 

bolt head. Grind it way down to a narrow ring around

the wrench head. Two man project as one has to be outside while one is scrunched up in the foot well inside. 

Use worm clamps to put it on the end of a long screw driver so you can reach the
bolt head easier. 

When you have the nose wheel off the ground lay under the wheel well and move the tire left and right 

and you'll see where there is play in the monkey motion linkage from pedals to nose wheel. If you have more than

a few degrees of left-right you have wear in the linkage. 

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19 hours ago, mooniacX said:

I am curious as to if you fixed the darting issue? if so what did you do?

Well...  "fixed" is a strong word here.  Worked-around it, maybe?  I've found (thanks to another MSer) that I was landing far too nose-up at touchdown, which when corrected leads to mostly docile handling on the rollout (it still wants to meander a little, but it's not darting by any stretch of the imagination).

It's still going to get fixed properly (maybe in the next day or two; depends on weather), but for now I think it's perfectly fine for someone who knows how to properly land a Mooney.

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Years ago when I did the SB202 on a 1965 C, it was a night and day difference.  There was no question that was the problem. It was not a matter of technique.

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Interesting...  So the difference in my technique is that I'm not letting the nose rise so high in the flare, so it settles in a lot more smoothly at touchdown (within the limits of my skill, that is).  Before, it would set down, then start steering pretty hard to the left (usually) or right (once or twice) a moment after touchdown (probably when it started getting good traction).  Now, it still likes to meander (need the steering horn bushing replaced!), but at least it's controllable.

Either way, I'll report back once it's back from the shop.  We'll see how it goes.

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I also have the sb202 spacer installed and have never flown the plane without it (the plane came to me that way). I am curious if anyone has noticed (before-after) a difference in the amount of back pressure required to raise the nose for take-off.....the SB202 spacer lowers the height of the nose, thereby lowing the AOA during the initial part of the takeoff roll. The spacer also decreases prop-to-ground clearance, which is an undesirable side effect.

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it doesnt lower it that much, the airplane is still +2.5 ANU on the ground

 

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2 hours ago, PilotCoyote said:

I also have the sb202 spacer installed and have never flown the plane without it (the plane came to me that way). I am curious if anyone has noticed (before-after) a difference in the amount of back pressure required to raise the nose for take-off.....the SB202 spacer lowers the height of the nose, thereby lowing the AOA during the initial part of the takeoff roll. The spacer also decreases prop-to-ground clearance, which is an undesirable side effect.

Also, a small difference in trim or weight loading will change that force quite a bit.  Our trim indicator isn’t exactly a fine tuned scientific instrument, so you can have it “set at takeoff” and there is a lot of “wiggle room” in that setting.

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5 minutes ago, Ragsf15e said:

Also, a small difference in trim or weight loading will change that force quite a bit.  Our trim indicator isn’t exactly a fine tuned scientific instrument, so you can have it “set at takeoff” and there is a lot of “wiggle room” in that setting.

Very true..

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Keep in mind...

1) While you are sorting out the hardware, and the skills...

2) in between the two... is thin layer of rubber...

3) A good pair of boots is great to have when hiking across a field in snowy Wisconsin... but something lighter will help to know if you are accidentally stepping on the brakes... even partially...

4) There are some pilot’s shoes available... extra expensive because you can run at 300nmph with them on...

5) there are also deck shoes you can use when you get to the yachting seen at the end of the flight...

6) Sperry docksiders are cool, and they come in a driver’s edition... very easy to tell if that is rudder, or if that is brake you are touching....

Sounds like you may get a pair of fancy shoes while you sort out the middle zone... :)

PP thoughts only, not a CFI...
Best regards,

-a-

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Haha, yeah...  I'm pretty careful with my foot placement on the pedals, but there's always the possibility I'm on the brake and don't realize it.  Thanks for the pointer!

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Another work around you might try until you get it checked out is to run the mains 5 psi low. The slight extra rolling friction dampens out the yawing moment.

Skip

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