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Maintain those tailwheels

rv8ch

Well Known Member
Patron
quick reminder - keep the tailwheel in good shape.

https://www.ntsb.gov/_layouts/ntsb.aviation/brief.aspx?ev_id=20200304X54241

NTSB Identification: CEN20CA114

14 CFR Part 91: General Aviation
Accident occurred Wednesday, March 4, 2020
Aircraft: Vans RV8
Injuries: 2 Uninjured.

NTSB investigators used data provided by various entities, including, but not limited to, the Federal Aviation Administration and/or the operator and did not travel in support of this investigation to prepare this aircraft accident report.

The pilot of the tailwheel-equipped airplane reported that he made a normal landing approach to the runway with a direct crosswind of 15 knots and gusts reaching 23 knots. The pilot reported that he was initially able to maintain directional control with normal flight control inputs after the airplane touched down on the main landing gear; however, when the tailwheel touched down the tail began to weathervane and the airplane veered to the right. The pilot was unable to regain directional control with an application of full left rudder and left brake before the airplane departed the right side of the runway and struck a precision approach path indicator lights (PAPI) system. The left wing, left horizontal stabilizer, and left elevator were substantially damaged during the collision with the PAPI system. A postaccident examination and functional test of the steerable tailwheel revealed that the spring-actuated key slide would stick in the retracted position within the tailwheel fork, which allowed the tailwheel to caster instead being steerable within the normal limits intended for takeoff and landing. Additional examination revealed that the slot in the tailwheel fork that held the spring-actuated key slide was slightly deformed, and that the key had several raised edges that caused the key to bind when fully retracted in the slot. It is likely that the tailwheel was able to caster during landing, which resulted in the pilot's inability to maintain directional control after the tailwheel had touched down during landing roll.
 
The maintenance instructions I got when I replaced mine with the Condor says to remove and grease that pin every 6 months.
 
I would suggest cleaning, inspecting, and lubricating every 25 hours, or six months, whichever comes first. This is a high wear item that needs attention to keep it working right. It is also a good idea to have a spare pin, and ?arm? in inventory as they do wear out.
 
Is a 15 kts gusting to 23 kts direct crosswind normal for an RV8? Could all of the tail wheel damage have been done on that landing?

Based on my C195 experience those winds are unacceptable for a tailwheel but I haven?t flown my RV8 yet either.
 
Is a 15 kts gusting to 23 kts direct crosswind normal for an RV8? Could all of the tail wheel damage have been done on that landing?

Based on my C195 experience those winds are unacceptable for a tailwheel but I haven?t flown my RV8 yet either.

I would have been comfortable with that wind level in my RV4 & have landed in similar conditions many times with no trouble.
 
I've had enough failures in various tailwheel airplanes to never assume the TW is functioning correctly. In gusty conditions this means one must get slowed down aggressively.
 
After having this problem occur while on a trip I carry a spare pin in my traveling kit, along with a small file.

Regarding crosswind capability, this topic has come up in several previous threads that tend to escalate into increasingly dubious claims. My favorite is post #21in this thread:

http://www.vansairforce.com/community/showthread.php?t=111399&highlight=g54&page=3

Yep....that is a good one. ;)

I landed my RV-6 with 19ktsG26 burbling over buildings and hangars within 10* of straight across the runway and decided I didn't want to do that again. Nothing bent but it was kinda noisy.....

The tailwheel pin needs to be inspected every Condition Inspection and burrs filled off the edges of the pin. If the pin is kept in good condition and lubed it should be very reliable.
 
Is a 15 kts gusting to 23 kts direct crosswind normal for an RV8? Could all of the tail wheel damage have been done on that landing?

Based on my C195 experience those winds are unacceptable for a tailwheel but I haven?t flown my RV8 yet either.

Direct 15 G25? I think the goal is knowing how to do it, and how to avoid proving it.

Tailwheel maintenance:

https://www.danhorton.net/Articles/1013_TailWheelTuneUp.pd.pdf

Dan is spot on!

I have landed mine in a 32 knot direct crosswind, one time!
The controller watching me said he had his hand on the crash button the entire time.

While I can do it and practice whenever there is a crosswind, there is a huge pucker factor but an RV can handle some amazing crosswinds.
 
My RV-8 had that problem when I bought it and flew it home, coast to coast. I couldn't figure out why my tailwheel skills were so bad...

That experience made me gun shy, and certainly detracted from the joy of ownership...
 
Thanks for your words of wisdom guys , I just did my maintenance at my last annual in the fall but before that it was only done once in my first 150 hrs when I installed my Bell tail wheel on , I?m definitely uping my maintenance game after reading this post !
 
Dan H, in the article, what are the part numbers of the fittings used to attach the springs to the tailwheel control arm?

AN115 cable shackle. I despise the bent wire clips usually seen in that location.

BTW, IMHO this is the the best tailwheel ever: https://www.jdair.com/complete-tailwheel-assembly-for-vans-rv/

The roller elements on the shaft means it steers with minimal pedal pressure...like power steering. That relates right back to the lock pin issue discussed here. The pin and its companion notch in the steering arm links the steering arm and the fork, so if the fork is easier to turn, the pin sees less load.
 
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Aren't there castering tailwheels?

I had the experience early in Phase I with a stuck pin. I think it was 4-5 flights before I discovered it. Not so bad, actually, as I had no significant cross wind. It was only found as the rudder did not latch on the ground when setting the tow bar, not from TO/Landing performance. Fix it, but don't fear it.

I used the tips from Flyboy to file and adjust the Vans unit and have had excellent results with a condition inspection interval. With the cold temps here I use oil, not grease, on the pin. Maybe, I will try a touch of speedometer cable grease, I have a 1000 yr supply. YMMV
 
Early on I too had a stuck pin and didn't notice it until I went to a fly-in and realized the rudder was free to swing when I tied the plane down.

The little spring loaded locking pin developed a burr on it that kept it from going back out and locking the tailwheel in place. A little file solved that problem.

Later on, I replaced the pin with one made of hardened steel an the problem never returned.
 
Castoring Tailwheel

This is a topic I struggled with as I built my RV and began flying my first tailwheel aircraft.

I envisioned a crosswind situation which provided a peak need for directional control around the <=40 knot range right when when the tailwheel begins to take on directional control influences.

I hold ailerons and elevator as appropriate and naturally feed in rudder to counter the gust then 'click' the tailwheel castors by design right at the moment you need its full authority.

I am not saying that a controlled tailwheel is required, history shows it is not. But it seems that the sudden transition at the exact moment when you need consistent control response is a little problematic no?
 
This is a topic I struggled with as I built my RV and began flying my first tailwheel aircraft.

I envisioned a crosswind situation which provided a peak need for directional control around the <=40 knot range right when when the tailwheel begins to take on directional control influences.

I hold ailerons and elevator as appropriate and naturally feed in rudder to counter the gust then 'click' the tailwheel castors by design right at the moment you need its full authority.

I am not saying that a controlled tailwheel is required, history shows it is not. But it seems that the sudden transition at the exact moment when you need consistent control response is a little problematic no?

Possibly. However, if you get the stick in your lap, and keep it there, at those speeds, there is a lot of down force on the tailwheel and it is going to help you keep things straight. You will transition out of your cross control quickly once the tailwheel makes contact.
This plays into the two schools of thought in crosswind landings. Those that prefer wheeling it on, and those that want that tail on the ground ASAP
Regardless, when you put the tail down, get the stick in your lap and keep it there, all sins are forgiven, and a properly maintained tailwheel should not unlock.
 
When the tailwheel castors

So my concern is that a properly maintained tailwheel castors when we get to our full rudder travel by design. So I am not talking about an inadvertent release, I am addressing a design release just when we need it most.
 
So my concern is that a properly maintained tailwheel castors when we get to our full rudder travel by design. So I am not talking about an inadvertent release, I am addressing a design release just when we need it most.

You mean it unlocks into full swivel right at full rudder deflection? Yep, lots of them like that. So change it. Move the link points inboard on the rudder horn or outboard at the tailwheel arm (i.e. a longer arm).
 
Slack in the chains

My rudder will deflect almost fully before it stears the tailwheel. It might even take a little shot of prop blast or brake to unlock it to swivel. I hear all the time how someones plane darts left or right when the tail touches down. I just prefer it to be less touchy.

Cm
 
My rudder will deflect almost fully before it stears the tailwheel. It might even take a little shot of prop blast or brake to unlock it to swivel. I hear all the time how someones plane darts left or right when the tail touches down. I just prefer it to be less touchy.

Cm

I totally agree with you Christopher! If springs are tight the tail wheel darts every movement of the peddles. I have lots of slack in my -7 and 1700 hrs TW time and I let the rudder do ALL the work while the wheel rolls straight, not darting side to side, as tight springs do. Then when I start to loose the effectiveness of the rudder I have enough peddle left to steer with the tail wheel.
I guess it what ever you get used to 🥴
 
Tailwheel control

The same thing just happened to me a couple of weeks ago. The tail wheel is greased every 100 hours or year whichever comes first. The airplane had 50 hours on it. The grease was all dry and caked up. A quick bunch of throttle and a little opposite brake prevented any incidents.
Dan Hortons article is a good one but information like this needs to be be on a site that is localized rather than looking all over the Internet. This one needs to have an important maintenance page. "Safety" is a good start and the S B and letters are good, but just saying.
So while I'm at it Our airplane is equipped with the push pull tail wheel springs rather than the chain and springs. Our plane has one on each side rather than just one side because they break. When one breaks you still have the other one working for you. That means they need to be preflighted because you can't always tell when they are broken by just looking at them.
 
For those of us that aren't familiar with tailwheel maintenance or have been putting off maintenance for fear of disassembly, I put together a short video discussing the inner workings of this mechanism.

https://youtu.be/LkBz3UqRanQ

I've got a longer video in the works dealing with troubleshooting common issues that we see in this mechanism, but it's not ready quite yet.

If you're having issues or need advice with a tailwheel assembly, don't hesitate to get in touch with us... we're here to help!
 
I had the same situation in my F1 this year. Its difficult to maintain directional control when it castors and I only had a 10 knot crosswind component. I replaced the pin and went through the entire assembly. Its a high wear item but the parts are cheap.
 
VAF Helped Fix This Issue

Purchased and flew my RV-6 quite some time before I found out that the problem was the pin. Thank You VAF!

Mine was stuck, just learned to be quick on the pedals and brakes for directional control. Now that it is fixed, feel lucky to have made it through those first months, helped train me well for TWs that actually work!

Battle Mountain, NV (KBAM) had some interesting winds last year on the 7th of June 2019.

Winds-KBAM-SC.png


Winds-KBAM-7-Jun19.jpg


Battle Mountain has 4-big runways, first runway was not an option by the time I arrived. Decided to commit to the second choice as the wind was changing to that direction. Timed it well, not a bad x-wind at 30 degrees. The Gusts were interesting; rock and roll all the way to the ground, love the handling the RV provides.

Plenty of rudder still available. You actually had to fly the RV on the taxiway, the whole way to parking! One of the reasons took the runway used, the taxiway would be almost aligned with the wind direction, did not want that kind of wind behind me.

Big guy came out and leaned on the wing when tying down. Nice crew and a courtesy car available. Discount rates at one of the hotels in town.

Mike
 
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I went out last Friday, (after reading this), and pulled it all apart, primarily to check the wear on the pin, and the 1/2 moon slot it rides in. All looks good, didn't appear that the pin or the left and right edges of the slot had any abnormal wear on them. (Likewise, the notch in the control arm (that connects to the chains). Regreased it all, and put it back together again. This normally gets taken care of for me on my conditionals/annuals, so I hadn't personally looked at it for about 3 years or so. This article inspired me. I write this, because I'm neither a builder, or a mechanic, but the tailwheel assembly is easy enough for even a guy like me to handle. (All my parts, tailwheel fork, locking pin, and control arm are from Vince Frazier, Blake's father--I guess the parts are all steel now??)

About 1 1/2 years ago, I was landing (with the mechanic in the back seat.) I wasn't aware of any strong crosswinds, but suddenly the aircraft went left, very very left, off the runway into the grass. I had full right rudder applied trying to stop it, but to no avail. Luckily, there was no damage to the airplane. Still can't figure out why that happened.:confused:
 
Super easy to check your tailwheel during preflight. A light push side to side and observe it is locked. It will also tell you if it is sticking, or sticky, and needs service.
I know some folks here are not mechanics and rely on others for maintenance. However, you should be familiar with all the critical control items, how they work, and what their purpose is, so you can evaluate your machine is in a safe condition to fly.
Flying for months with a critical component not working shouldn?t happen. That?s why we preflight. A preflight check list would be a must for the non-mechanically inclined.
 
Suggested Maintenance

Hi Everyone,

First, thanks Dan for the kind words on my JD Air tailwheel assembly. A lot of thought and testing went into the development. Still, without proper maintenance they can all fail.

I have conversed with Vic on this issue and Blake and I have talked. We all agree that regular maintenance is needed on the tailwheel assemblies. The tailwheel takes an absolute beating back there but is probably one of the most over looked pieces on our planes.

Over the years I have talked with dozens of owners that have had steering issues even it isn't our product. Those having problems generally have one thing in common, lack of maintenance on the tailwheel and in some cases lack of knowledge. I see this more often in owners that bought their planes than those who built them.

My recommendation is very simple. Do a complete removal, cleaning, regreasing and reassembly every 25 hours when you change your oil or no more than 6 months if you don't get the 25 hours. The logic is simple, you've got to wait for the oil to drain anyway. Why not do the tail wheel?

I have a saw horse that I cut the legs down on, probably 14" high. I lift the tail and put the saw horse under the rear bulkhead, with foam padding. I get the oil draining and then get ready to service the tail wheel.

Before you start, one of the hardest things in getting the tail wheel set up is determining just how tight to get the nut so it operates as intended. Once this is set up you hate the thought of losing it. I used a jewelers file with a sharp edge and made a mark on nut and on the housing of the yoke as an alignment point. Look and how many threads are showing and take a picture of it. Now you have a baseline.

Remove all the parts and clean them with brake cleaner. Try to get all the grease out. Inspect the pin for any signs of nicks or burrs. File out as necessary. Same with the receptacle in the arm. Put fresh grease in and reassemble.

It took longer to write this than to do it!! Follow these guidelines and you'll have a happy tail wheel and eliminate flying surprises.

Feel free to call if you have any questions!!
 
My recommendation is very simple. Do a complete removal, cleaning, regreasing and reassembly every 25 hours when you change your oil or no more than 6 months if you don't get the 25 hours.

Absolutely. I lift the tail for oil drain anyway. It's 50 hours for me, but a tailwheel interval really depends on operating conditions. Offhand I don't recall ever seeing one with shaft seals, so it's all about the local dirt/grit.

Before you start, one of the hardest things in getting the tail wheel set up is determining just how tight to get the nut so it operates as intended.

That's odd. The washer sits on top of the shaft, and is clamped firmly to the shaft with the nut. The washer sandwiches the control arm between the top of the housing and the underside of the washer with a small clearance set by the relative lengths of the housing and shaft. Put another way, the sum of A+B is slightly less than C, ballpark 0.020". The control arm will have a little wiggle room with the nut fully torqued.

Tailwheel.jpg
 
That's odd. The washer sits on top of the shaft, and is clamped firmly to the shaft with the nut. The washer sandwiches the control arm between the top of the housing and the underside of the washer with a small clearance set by the relative lengths of the housing and shaft. Put another way, the sum of A+B is slightly less than C, ballpark 0.020". The control arm will have a little wiggle room with the nut fully torqued.

I'm sure that is the way the tailwheel yoke is designed, but both tailwheel yokes I've used on my RV-6 have required a bit of finesse when it comes to tightening the nut. It is possible to get the nut tight enough to bind the yoke, but it isn't difficult to adjust for smooth operation (sorta like tightening/loosening an axle nut). Perhaps there was some manufacturing variation in the housing.
 
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So you guys are operating with the washer not firmly clamped to the top of the shaft? That ain't right.

BTW, I understand the axle nut analogy, but if the washer is free to rotate, the nut needs to be keyed, just like that axle.
 
So you guys are operating with the washer not firmly clamped to the top of the shaft? That ain't right.

BTW, I understand the axle nut analogy, but if the washer is free to rotate, the nut needs to be keyed, just like that axle.

Dan, I don't know how much the washer is rotating, but the nut hasn't loosened in twenty years between many relubes/servicing. It only takes a tiny bit of rotation of the nut to take it from too tight to just right. I've considered filing the housing a few thousandths but since there have been no service issues and the tailwheel works flawlessly I've left well enough alone all these years.
 
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Evidently A+B was to excessive on mine, and someone put a washer underneath the collar. I had been flying that way since I bought the plane. There were several signs that should have told this was wrong.

First, (and most important); the airplane had horrible ground handling characteristics. I had flown a couple tail wheels years back doing evaluations; then got an endorsement in a cub quickly followed by transition training in an 8. The 8 I received training in had a van's setup with chains. It had some caster, which does add to positive stability, the chains allow for a little more rudder prior to tailwheel action than mine is setup. My tailwheel is aftermarket, sits vertical relative to the ground, neutral stability; and has wires and springs. I had convinced myself that little positive stability and chain setup on the other airplane were significantly enhancing to ground handling. What was happening was the pin would disengage occasionally in my tailwheel (not to my knowledge); and this was very unpredictable. I had to use the brakes way more than I should. It would be holding center line with my inputs then just randomly dart off. I went off roading once (my runway is 23') when I was about 40 knots decelerating on what I thought was a low wind day. I had let my guard down a little, then I am pretty sure a gust of wind hit, now I know the pin came out, and I swerved. Luckily no damage, and got back on the runway. There were numerous other times this swerve happened on much larger runways and I saved it with a combination of rudder and brakes. At my home field I stayed on it like it was a boat landing and flew it until the engine was off and I was stopped (which is how a tailwheel should be handled anyways, but I gave way more attention than normal), and I always dreaded coming home. Anyways, I was compensating for an abnormal, unpredictable, negative behavior during ground handling.

Second, the pin and the notch in the control arm where the pin sits had a couple burs in them. I even broke one pin. The burs were towards the bottom of control arm. So I took the plate out, filed out the burs and flipped it.

Third, (after seeing some people talk about nut tightness, I figured I should post this). On a recent landing at my home field, I had used so much brake to stay on the runway the tail came off the ground. Scared the **** out of me. Post flight, the nut was loose! I would tighten it, if too much the tail wheel wouldn't spin, not enough and it would get loose (found this out the hard way).

So I after almost running off the runway again (probably 70ish hours now since I bought the plane); I decided to inspect the tail wheel again ( I probably inspect it at about 25 hour intervals, but do it now about every three flights). I pulled it all apart, cleaned, greased, and put it together. I tightened the nut, and the tailwheel locked up. For some reason, I decided to look at the assembly this time, thinking it should not lock up regardless of how tight I torque the nut. When I pulled the nut off and looked at the pin, the light bulb (and a very bright one) was finally on! I looked at the mechanism, and the pin was riding in the lower maybe 30% of the control arm (just a guess could have been less. Someone had added a washer below the collar {A in Dan's picture} and when I put everything back together I put the washer in too (every time). Well I removed the washer, put everything back together. Now the pin was all the way in the notch of the control arm, I could tighten the nut as tight as I wanted, and everything worked! What was happening, was the engagement surface of the pin was not enough to hold the tailwheel, due to the excessive height of the washer. This led to my first problem, random unlocking. Also, problem two, because pour engagement it led to burs. Problem three compounded one and two. Because I could not torque the nut properly or it would lock the tail wheel, it was always a little loose; cycling the tailwheel/rudder back and forth on the ground would cause the nut to loosen further resulting in less engagement surface and so on. pin inspection with the washer out I think I know why someone added a washer. The 0.020 that Dan describes as C - (A + B) was more like 0.20. The control arm wobbled very badly. Rather than put a washer in that was 0.18ish, a washer of something like 0.40 was used (just guessing at the numbers). So I made a shim that would result in a spacing out 0.020, reassembled; everything functioned properly and the control arm had minimal play.
 
That's odd. The washer sits on top of the shaft, and is clamped firmly to the shaft with the nut. The washer sandwiches the control arm between the top of the housing and the underside of the washer with a small clearance set by the relative lengths of the housing and shaft. Put another way, the sum of A+B is slightly less than C, ballpark 0.020". The control arm will have a little wiggle room with the nut fully torqued.

Tailwheel.jpg

This has also been my experience with stock Van's hardware as well. One note though: I found that the washer was bottoming out against the radius of the transition to the threaded portion of the steering shaft instead of on the face of the "step". I added a chamfer to the ID of the bottom side of the washer so that it sits flat on the step face. This reduced what I felt was excessive end-play of the steering arm but still allows everything to swivel freely.

Secondly, I have not had a stuck pin in 900 hours of airframe time. I clean and re-lube everything 2-3 times per year, which is about every 40-50 hours or so. I use grease on the steering shaft, but keep it below the locking pin area. I use LPS-1 "greaseless lubricant' on the locking pin parts and the steering arm. I also slightly knocked-down the edges a little of the locking pin and the broached bore of the steering yoke with a scotch-bright wheel because these are the areas where burrs begin to form that can cause to pin to stick.

Skylor

Skylor
 
I, too cannot fully tighten the nut without it binding. So I tighten ?just enough? to where it doesn?t bind.
 
The big washer is adjustable! Take the washer and stick a bolt in it., half inch diameter bolt should work. Drop this into the end of a short piece of pipe mounted in a vice. Now wack the end of the bolt with a hammer. You will introduce a washer that is now slightly concave. This method can be used to fine tune the clearance of the washer ?tension? on the bolt and remove any vertical slop in the tail fork.

It is also very satisfying to hit an airplane part with a large hammer.
 
So you guys are operating with the washer not firmly clamped to the top of the shaft? That ain't right.

BTW, I understand the axle nut analogy, but if the washer is free to rotate, the nut needs to be keyed, just like that axle.

What Dan says is correct. If you aren't tightening the large top nut down all the way, something is wrong.

There are manufacturing variations between different vendors and batches, and plain old wear to consider.

When everything is brand new, the fit may be tight. If it's so tight that the assembly binds up when you tighten the nut ALL the way down, then it is acceptable to remove a wee bit of the bronze bushing on the bottom of the housing to make it fit properly.

Later, when Mother Nature's dirt has worn that same bushing down a bit, it is acceptable to add a shim washer. Blake sells stainless washers in .015", .020", and .025" thicknesses.

Bottom line is that you must maintain the tailwheel, no matter who made it. None of them are maintenance free. Not one.

Here is a link to Blake's maintenance tips
 
I don?t understand how anyone has doubts. Flyboys has some easy to understand instructions that even non mechanics like me find clear and easy to follow.
 
Tailwheel troubleshooting master list

Since we're on the subject and I've already promised a video about troubleshooting, I thought I'd go ahead and share the master list of troubleshooting issues that we commonly come across. This is actually more or less the script of the troubleshooting video, and we'll probably turn it into a paper document soon but I didn't want to wait for the production delays to get the information out there!

Let me know if you have a mystery issue or common problem that should be added to the list (email [email protected])!

Before we get started, let's define a few key pieces of terminology so we're all using the same words for the same parts. Forgive the crude Sketchup drawing here:
Tailwheel-Terminology.jpg




A few common issues and how to address them

- Locking pin jammed in the housing
○ If debris or burrs inhibit the smooth movement of the locking pin, it may jam inside its housing. This will present different symptoms depending on how it has jammed. If it jams all the way inside the housing, the tailwheel won't lock properly or will only lock sporadically. You can remove the pin, clean it, dress any burrs you find, and make sure the housing is cleaned before regreasing everything. If the pin is really stuck, a pin punch can be used to force it out from the back side, though make note of the location of the roll pin which forms the backstop on the square hole. After you reassemble the tailwheel, make sure the pin moves in and out of the housing smoothly and locks smoothly with the control arm.
○ If the pin jams all the way or partially out, your tailwheel will remain locked and the forces put onto the tailwheel may damage some parts of the assembly. You'll most commonly see notches form on the locking pin nose and sometimes the bushing can be damaged by a pin forced to turn through the softer bushing material.

- Tailwheel unlocking at inappropriate times
○ Your tailwheel should unlock ONLY when it is turned past the angle at which the locking pin is retracted. It should not unlock by a sideways force alone? so if stepping on the pedal is enough to unlock a tailwheel that is otherwise in trail, something is wrong.
○ What's most likely at fault is that the pin is not sufficiently engaged in the control arm notch. Van's parts cut the notch fairly shallow, meaning that the pin is limited in how far it can extend. In the right circumstances, a propagation of error between a shallow notch, an excessively rounded pin, and worn corners on the control arm can cause a sideways force on the control arm to force the locking pin back into its housing, unlocking the tailwheel.
○ The solution here is to fix all the little problems that added up to this. Our control arms feature a deeper notch, which means the locking pin can engage more fully and get contact between the straight sides of the notch and the straight sides of the pin.
○ We also recommend blunting the nose of the locking pin, giving them more of a "bull nose" profile rather than a fully round one. Make sure the corners of the locking pin are still rounded so that they don't catch on the walls of the groove in the mounting socket.

- Tailwheel assembly binds or feels tight
○ If the tailwheel steering feels tight on assembly, the likely culprit is that the top nut is compressing the wrong parts of the assembly. If you look across the top of the assembly, you've got the top surface of the control arm which is probably just about in line with the top surface of what I'll call the "shoulder" of the tailwheel shaft. For proper function, these two surfaces need to be close to coplanar, but the "shoulder" should stand out "proud" - just above the top surface of the control arm.
○ If the opposite is true, and the control arm surface sits above the shoulder of the tailwheel shaft, the system will bind, as the washers on top will tighten onto the control arm, which will then compress the outside of the mounting socket to the bottom of the tailwheel fork. You can easily tell if this is the case, as the tailwheel will feel tight and resist swiveling when the top nut is tightened down but will loosen up if the nut is backed off.
○ You can solve this issue by carefully removing material from the top of the mounting socket using a belt sander, ideally just enough to get the tailwheel shaft shoulder above the top surface of the control arm. Alternatively, you can add a 1/2" ID shim washer to the top of the tailwheel shaft shoulder (find these shim washers on our website)
○ Note that if you have the JDAir mounting socket (or tailwheel yoke, as they call it) with the needle bearings in the shaft, you should not sand this unit, as it will likely result in debris from the sanding getting into the needle bearings. Instead, use 1/2" ID shim washers on top of the tailwheel shaft to configure the assembly.

- Tailwheel has too much vertical play
○ It is possible as parts wear for vertical play or "slop" to develop in the tailwheel. If this play is strictly up and down, it's generally not a problem unless it's very severe. If you would like to address vertical play here, you can use a feeler gauge to determine how much play you have and use a 7/8" ID shim washer to address it. This shim washer can go under the mounting socket or on top of the control arm. Be careful, however, not to shim too much, as this can cause the tailwheel to bind.

- My control arm has play
○ I often get calls from customers concerned about play or slop in the control arm piece on top of the mounting socket. This play can be either up and down or side to side. These parts are made with somewhat loose fit so that they don't jam and malfunction, so a little bit of play is normal. How much is too much? I wouldn't necessarily worry too much about this unless it is causing some other tailwheel malfunction. If you are concerned about it, you can check the control arm, tailwheel fork, and locking pin for excessive wear and replace parts as necessary.

- Tailwheel has play other than vertical
○ If the bushing in the mounting socket has become excessively worn, the tailwheel may develop play in directions other than vertical. While it usually would take quite a lot of slop in this system before real problems develop, you can consider replacing the bushings in the mounting socket, or replacing the whole mounting socket altogether.
○ To do this, you need to determine what type of mounting socket you have.
  • The Van's standard part is easy to identify by the bronze bushing inside the mounting socket. These will usually, but not always, also feature a non-functional grease zerk, which serves as a bushing retainer. You should be able to source replacement bushings at an industrial supply shop. When you're replacing the bushings, make sure to loosen the grease zerk if present, press the old bushings out, and replace with new bushings. Make sure to reopen groove in the top mounting socket with a Dremel tool or mill once the bushings are in, as this is important for the function of the locking mechanism
  • Our "Screaming Eagle" mounting socket has a dark grey, engineered plastic bushing. You can find replacement bushings on our store.
  • JD Air's tailwheel yoke performs the same function, though its live bearings should not wear over the life of the product. If you have excessive play in this unit, something else is going on.

- Tailwheel tire wears unevenly or fork sits crooked
○ If your mounting socket was not installed vertically the first time, your tailwheel fork will sit crooked and your tire will likely wear unevenly.
○ This can be addressed by replacing the mounting socket, which involves match drilling a few holes. For more on this process, see our document "Changing a mounting socket" or contact us.
- Tailwheel strikes bottom rudder cap
○ The tapered rod spring that makes up the tailwheel can end up bent over time and occasional hard landings. You should normally have 3 inches or more of clearance between the top of the tailwheel and the bottom of the rudder. If your tailwheel seems to close to your rudder or if you notice damage to the fiberglass from a rudder strike, you may consider replacing the tail spring. See our document "Drilling the tail spring" for more information
○ It is also possible to put a downward bend into the spring, as discussed here.

- Issues with Steering Link Adjustment
○ The next three problems are most commonly found in situations where a steering link system has replaced the stock steering chains. If your tailwheel does not unlock on one side, if you notice a "notch" in your locking pin during servicing, or if your tailwheel "bangs" when unlocking on one side, you should check your steering link for proper adjustment. All three issues are indicative that the link needs to be adjusted for length. What's happening is that the rudder hits the stop before the tailwheel reaches its unlock position, causing the force from the tailwheel to jam against the stop. See our Steering Link installation documents for more information.
 
Since we're on the subject and I've already promised a video about troubleshooting, I thought I'd go ahead and share the master list of troubleshooting issues that we commonly come across. This is actually more or less the script of the troubleshooting video, and we'll probably turn it into a paper document soon but I didn't want to wait for the production delays to get the information out there!

Let me know if you have a mystery issue or common problem that should be added to the list (email [email protected])!

Before we get started, let's define a few key pieces of terminology so we're all using the same words for the same parts. Forgive the crude Sketchup drawing here:
Tailwheel-Terminology.jpg




A few common issues and how to address them

- Locking pin jammed in the housing
○ If debris or burrs inhibit the smooth movement of the locking pin, it may jam inside its housing. This will present different symptoms depending on how it has jammed. If it jams all the way inside the housing, the tailwheel won't lock properly or will only lock sporadically. You can remove the pin, clean it, dress any burrs you find, and make sure the housing is cleaned before regreasing everything. If the pin is really stuck, a pin punch can be used to force it out from the back side, though make note of the location of the roll pin which forms the backstop on the square hole. After you reassemble the tailwheel, make sure the pin moves in and out of the housing smoothly and locks smoothly with the control arm.
○ If the pin jams all the way or partially out, your tailwheel will remain locked and the forces put onto the tailwheel may damage some parts of the assembly. You'll most commonly see notches form on the locking pin nose and sometimes the bushing can be damaged by a pin forced to turn through the softer bushing material.

- Tailwheel unlocking at inappropriate times
○ Your tailwheel should unlock ONLY when it is turned past the angle at which the locking pin is retracted. It should not unlock by a sideways force alone? so if stepping on the pedal is enough to unlock a tailwheel that is otherwise in trail, something is wrong.
○ What's most likely at fault is that the pin is not sufficiently engaged in the control arm notch. Van's parts cut the notch fairly shallow, meaning that the pin is limited in how far it can extend. In the right circumstances, a propagation of error between a shallow notch, an excessively rounded pin, and worn corners on the control arm can cause a sideways force on the control arm to force the locking pin back into its housing, unlocking the tailwheel.
○ The solution here is to fix all the little problems that added up to this. Our control arms feature a deeper notch, which means the locking pin can engage more fully and get contact between the straight sides of the notch and the straight sides of the pin.
○ We also recommend blunting the nose of the locking pin, giving them more of a "bull nose" profile rather than a fully round one. Make sure the corners of the locking pin are still rounded so that they don't catch on the walls of the groove in the mounting socket.

- Tailwheel assembly binds or feels tight
○ If the tailwheel steering feels tight on assembly, the likely culprit is that the top nut is compressing the wrong parts of the assembly. If you look across the top of the assembly, you've got the top surface of the control arm which is probably just about in line with the top surface of what I'll call the "shoulder" of the tailwheel shaft. For proper function, these two surfaces need to be close to coplanar, but the "shoulder" should stand out "proud" - just above the top surface of the control arm.
○ If the opposite is true, and the control arm surface sits above the shoulder of the tailwheel shaft, the system will bind, as the washers on top will tighten onto the control arm, which will then compress the outside of the mounting socket to the bottom of the tailwheel fork. You can easily tell if this is the case, as the tailwheel will feel tight and resist swiveling when the top nut is tightened down but will loosen up if the nut is backed off.
○ You can solve this issue by carefully removing material from the top of the mounting socket using a belt sander, ideally just enough to get the tailwheel shaft shoulder above the top surface of the control arm. Alternatively, you can add a 1/2" ID shim washer to the top of the tailwheel shaft shoulder (find these shim washers on our website)
○ Note that if you have the JDAir mounting socket (or tailwheel yoke, as they call it) with the needle bearings in the shaft, you should not sand this unit, as it will likely result in debris from the sanding getting into the needle bearings. Instead, use 1/2" ID shim washers on top of the tailwheel shaft to configure the assembly.

- Tailwheel has too much vertical play
○ It is possible as parts wear for vertical play or "slop" to develop in the tailwheel. If this play is strictly up and down, it's generally not a problem unless it's very severe. If you would like to address vertical play here, you can use a feeler gauge to determine how much play you have and use a 7/8" ID shim washer to address it. This shim washer can go under the mounting socket or on top of the control arm. Be careful, however, not to shim too much, as this can cause the tailwheel to bind.

- My control arm has play
○ I often get calls from customers concerned about play or slop in the control arm piece on top of the mounting socket. This play can be either up and down or side to side. These parts are made with somewhat loose fit so that they don't jam and malfunction, so a little bit of play is normal. How much is too much? I wouldn't necessarily worry too much about this unless it is causing some other tailwheel malfunction. If you are concerned about it, you can check the control arm, tailwheel fork, and locking pin for excessive wear and replace parts as necessary.

- Tailwheel has play other than vertical
○ If the bushing in the mounting socket has become excessively worn, the tailwheel may develop play in directions other than vertical. While it usually would take quite a lot of slop in this system before real problems develop, you can consider replacing the bushings in the mounting socket, or replacing the whole mounting socket altogether.
○ To do this, you need to determine what type of mounting socket you have.
  • The Van's standard part is easy to identify by the bronze bushing inside the mounting socket. These will usually, but not always, also feature a non-functional grease zerk, which serves as a bushing retainer. You should be able to source replacement bushings at an industrial supply shop. When you're replacing the bushings, make sure to loosen the grease zerk if present, press the old bushings out, and replace with new bushings. Make sure to reopen groove in the top mounting socket with a Dremel tool or mill once the bushings are in, as this is important for the function of the locking mechanism
  • Our "Screaming Eagle" mounting socket has a dark grey, engineered plastic bushing. You can find replacement bushings on our store.
  • JD Air's tailwheel yoke performs the same function, though its live bearings should not wear over the life of the product. If you have excessive play in this unit, something else is going on.

- Tailwheel tire wears unevenly or fork sits crooked
○ If your mounting socket was not installed vertically the first time, your tailwheel fork will sit crooked and your tire will likely wear unevenly.
○ This can be addressed by replacing the mounting socket, which involves match drilling a few holes. For more on this process, see our document "Changing a mounting socket" or contact us.
- Tailwheel strikes bottom rudder cap
○ The tapered rod spring that makes up the tailwheel can end up bent over time and occasional hard landings. You should normally have 3 inches or more of clearance between the top of the tailwheel and the bottom of the rudder. If your tailwheel seems to close to your rudder or if you notice damage to the fiberglass from a rudder strike, you may consider replacing the tail spring. See our document "Drilling the tail spring" for more information
○ It is also possible to put a downward bend into the spring, as discussed here.

- Issues with Steering Link Adjustment
○ The next three problems are most commonly found in situations where a steering link system has replaced the stock steering chains. If your tailwheel does not unlock on one side, if you notice a "notch" in your locking pin during servicing, or if your tailwheel "bangs" when unlocking on one side, you should check your steering link for proper adjustment. All three issues are indicative that the link needs to be adjusted for length. What's happening is that the rudder hits the stop before the tailwheel reaches its unlock position, causing the force from the tailwheel to jam against the stop. See our Steering Link installation documents for more information.

Hi Blake, Please check your PM,s
 
Since we're on the subject and I've already promised a video about troubleshooting, I thought I'd go ahead and share the master list of troubleshooting issues that we commonly come across. This is actually more or less the script of the troubleshooting video, and we'll probably turn it into a paper document soon but I didn't want to wait for the production delays to get the information out there!

Let me know if you have a mystery issue or common problem that should be added to the list (email [email protected])!

Before we get started, let's define a few key pieces of terminology so we're all using the same words for the same parts. Forgive the crude Sketchup drawing here:
Tailwheel-Terminology.jpg




A few common issues and how to address them

- Locking pin jammed in the housing
○ If debris or burrs inhibit the smooth movement of the locking pin, it may jam inside its housing. This will present different symptoms depending on how it has jammed. If it jams all the way inside the housing, the tailwheel won't lock properly or will only lock sporadically. You can remove the pin, clean it, dress any burrs you find, and make sure the housing is cleaned before regreasing everything. If the pin is really stuck, a pin punch can be used to force it out from the back side, though make note of the location of the roll pin which forms the backstop on the square hole. After you reassemble the tailwheel, make sure the pin moves in and out of the housing smoothly and locks smoothly with the control arm.
○ If the pin jams all the way or partially out, your tailwheel will remain locked and the forces put onto the tailwheel may damage some parts of the assembly. You'll most commonly see notches form on the locking pin nose and sometimes the bushing can be damaged by a pin forced to turn through the softer bushing material.

- Tailwheel unlocking at inappropriate times
○ Your tailwheel should unlock ONLY when it is turned past the angle at which the locking pin is retracted. It should not unlock by a sideways force alone? so if stepping on the pedal is enough to unlock a tailwheel that is otherwise in trail, something is wrong.
○ What's most likely at fault is that the pin is not sufficiently engaged in the control arm notch. Van's parts cut the notch fairly shallow, meaning that the pin is limited in how far it can extend. In the right circumstances, a propagation of error between a shallow notch, an excessively rounded pin, and worn corners on the control arm can cause a sideways force on the control arm to force the locking pin back into its housing, unlocking the tailwheel.
○ The solution here is to fix all the little problems that added up to this. Our control arms feature a deeper notch, which means the locking pin can engage more fully and get contact between the straight sides of the notch and the straight sides of the pin.
○ We also recommend blunting the nose of the locking pin, giving them more of a "bull nose" profile rather than a fully round one. Make sure the corners of the locking pin are still rounded so that they don't catch on the walls of the groove in the mounting socket.

- Tailwheel assembly binds or feels tight
○ If the tailwheel steering feels tight on assembly, the likely culprit is that the top nut is compressing the wrong parts of the assembly. If you look across the top of the assembly, you've got the top surface of the control arm which is probably just about in line with the top surface of what I'll call the "shoulder" of the tailwheel shaft. For proper function, these two surfaces need to be close to coplanar, but the "shoulder" should stand out "proud" - just above the top surface of the control arm.
○ If the opposite is true, and the control arm surface sits above the shoulder of the tailwheel shaft, the system will bind, as the washers on top will tighten onto the control arm, which will then compress the outside of the mounting socket to the bottom of the tailwheel fork. You can easily tell if this is the case, as the tailwheel will feel tight and resist swiveling when the top nut is tightened down but will loosen up if the nut is backed off.
○ You can solve this issue by carefully removing material from the top of the mounting socket using a belt sander, ideally just enough to get the tailwheel shaft shoulder above the top surface of the control arm. Alternatively, you can add a 1/2" ID shim washer to the top of the tailwheel shaft shoulder (find these shim washers on our website)
○ Note that if you have the JDAir mounting socket (or tailwheel yoke, as they call it) with the needle bearings in the shaft, you should not sand this unit, as it will likely result in debris from the sanding getting into the needle bearings. Instead, use 1/2" ID shim washers on top of the tailwheel shaft to configure the assembly.

- Tailwheel has too much vertical play
○ It is possible as parts wear for vertical play or "slop" to develop in the tailwheel. If this play is strictly up and down, it's generally not a problem unless it's very severe. If you would like to address vertical play here, you can use a feeler gauge to determine how much play you have and use a 7/8" ID shim washer to address it. This shim washer can go under the mounting socket or on top of the control arm. Be careful, however, not to shim too much, as this can cause the tailwheel to bind.

- My control arm has play
○ I often get calls from customers concerned about play or slop in the control arm piece on top of the mounting socket. This play can be either up and down or side to side. These parts are made with somewhat loose fit so that they don't jam and malfunction, so a little bit of play is normal. How much is too much? I wouldn't necessarily worry too much about this unless it is causing some other tailwheel malfunction. If you are concerned about it, you can check the control arm, tailwheel fork, and locking pin for excessive wear and replace parts as necessary.

- Tailwheel has play other than vertical
○ If the bushing in the mounting socket has become excessively worn, the tailwheel may develop play in directions other than vertical. While it usually would take quite a lot of slop in this system before real problems develop, you can consider replacing the bushings in the mounting socket, or replacing the whole mounting socket altogether.
○ To do this, you need to determine what type of mounting socket you have.
  • The Van's standard part is easy to identify by the bronze bushing inside the mounting socket. These will usually, but not always, also feature a non-functional grease zerk, which serves as a bushing retainer. You should be able to source replacement bushings at an industrial supply shop. When you're replacing the bushings, make sure to loosen the grease zerk if present, press the old bushings out, and replace with new bushings. Make sure to reopen groove in the top mounting socket with a Dremel tool or mill once the bushings are in, as this is important for the function of the locking mechanism
  • Our "Screaming Eagle" mounting socket has a dark grey, engineered plastic bushing. You can find replacement bushings on our store.
  • JD Air's tailwheel yoke performs the same function, though its live bearings should not wear over the life of the product. If you have excessive play in this unit, something else is going on.

- Tailwheel tire wears unevenly or fork sits crooked
○ If your mounting socket was not installed vertically the first time, your tailwheel fork will sit crooked and your tire will likely wear unevenly.
○ This can be addressed by replacing the mounting socket, which involves match drilling a few holes. For more on this process, see our document "Changing a mounting socket" or contact us.
- Tailwheel strikes bottom rudder cap
○ The tapered rod spring that makes up the tailwheel can end up bent over time and occasional hard landings. You should normally have 3 inches or more of clearance between the top of the tailwheel and the bottom of the rudder. If your tailwheel seems to close to your rudder or if you notice damage to the fiberglass from a rudder strike, you may consider replacing the tail spring. See our document "Drilling the tail spring" for more information
○ It is also possible to put a downward bend into the spring, as discussed here.

- Issues with Steering Link Adjustment
○ The next three problems are most commonly found in situations where a steering link system has replaced the stock steering chains. If your tailwheel does not unlock on one side, if you notice a "notch" in your locking pin during servicing, or if your tailwheel "bangs" when unlocking on one side, you should check your steering link for proper adjustment. All three issues are indicative that the link needs to be adjusted for length. What's happening is that the rudder hits the stop before the tailwheel reaches its unlock position, causing the force from the tailwheel to jam against the stop. See our Steering Link installation documents for more information.

Bingo, this is what I'm talking about. Even someone who isn't a mechanic/builder can easily understand.
 
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