Yet another tailwheel issue

[Saville]

I just read Pauls' thread and here is another slightly different one that I need to post:

RV-8 taildragger.

I notice that when the tailwheel is "reversed" as in this picture:



as it often is after rolling the plane backwards into the hangar, there is almost zero resistance on the rudder pedals when I cycle them. You can move the rudder back and forth with no resistance and the "bellcrank" in the photo moves along with the rudder easily. Tailwheel does not move.

But then when you place the tailwheel in the usual position, as in this picture:



and then cycle the rudder pedals you get one push with zero resistance and then the resistance to the pedals stiffens.

I get full rudder throw when it's stiff, and no adverse effects when in the air - plane is responsive as always. And you can feel the tail of the plane swish back and forth when on the ground so the tailwheel is being moved.

But I have to say this resistance has only recently come to my attention. Now I have only ~20 hours in the plane so I'm still learning a lot, but I don't recall it being quite so stiff when I first started flying the plane. Could be a lack of attention on my part as the entire plane was new to me. Could be I never taxiied it with the tailwheel reversed.

I will add that with the tailwheel inthe usual position, there is no resistance to my pulling on the rudder cables ahead of their attach points on the rudder. So there's no binding occurring in the fuselage. The additional stiffness seems to be an artifact of the tailwheel assembly itself.


So the questions are:

1) is the difference in pedal resistance expected?

2) Can the resistance get stiffer over time?

3) If so, why would that be? Is it possible that the pivot needs greasing/cleaning?

Any insight would be greatly appreciated.

[Sam Buchanan]

Originally Posted by Saville

I just read Pauls' thread and here is another slightly different one that I need to post:

RV-8 taildragger.

I notice that when the tailwheel is "reversed" as in this picture:


as it often is after rolling the plane backwards into the hangar, there is almost zero resistance on the rudder pedals when I cycle them. You can move the rudder back and forth with no resistance and the "bellcrank" in the photo moves along with the rudder easily. Tailwheel does not move.

But then when you place the tailwheel in the usual position, as in this picture:



and then cycle the rudder pedals you get one push with zero resistance and then the resistance to the pedals stiffens.

I get full rudder throw when it's stiff, and no adverse effects when in the air - plane is responsive as always. And you can feel the tail of the plane swish back and forth when on the ground so the tailwheel is being moved.

But I have to say this resistance has only recently come to my attention. Now I have only ~20 hours in the plane so I'm still learning a lot, but I don't recall it being quite so stiff when I first started flying the plane. Could be a lack of attention on my part as the entire plane was new to me. Could be I never taxiied it with the tailwheel reversed.

I will add that with the tailwheel inthe usual position, there is no resistance to my pulling on the rudder cables ahead of their attach points on the rudder. So there's no binding occurring in the fuselage. The additional stiffness seems to be an artifact of the tailwheel assembly itself.


So the questions are:

1) is the difference in pedal resistance expected?

2) Can the resistance get stiffer over time?

3) If so, why would that be? Is it possible that the pivot needs greasing/cleaning?

Any insight would be greatly appreciated.

If I understand your question correctly, what you are describing is exactly the way the tailwheel is designed to operate. Once the tailwheel exceeds ~45 degree deflection, it unlocks so it can be swung around as you described. Once it is returned to the normal position a spring-loaded pin in the mount relocks the tailwheel so you can control it with the rudder pedals.

It is good to disassemble the locking mechanism at condition inspection and clean/lubricate it so it will work as designed. It can get gummed up over time.

[Saville]

Thank you Sam. That's what I suspected but I wanted to check to be sure.

I take it that the tailwheel is disassembled by holding the wheel motionless and removing that large nut at the top?

[Veetail88]

Understanding how everything works is a powerful advantage to builders.

[Veetail88]

That's correct Saville. Just be careful when you slide the shaft out the bottom. There is a pawl in a slot in the top of the shaft that has a spring behind it so it may pop out on you. Don't loose the parts!

Like Sam said, clean it up, look the parts over for wear, lube it and put it back together.

[Saville]

Originally Posted by Veetail88

That's correct Saville. Just be careful when you slide the shaft out the bottom. There is a paul in a slot in the top of the shaft that has a spring behind it so it may pop out on you. Don't loose the parts!

Like Sam said, clean it up, look the parts over for wear, lube it and put it back together.

What is the recommended lubricant?

[Sam Buchanan]

Originally Posted by Saville

What is the recommended lubricant?

I use the same grease as used on the wheel bearings. Lots of opinions on which grease for the bearings but I use a good automotive grease.

[Chkaharyer99]

Originally Posted by Saville

So the questions are:

1) is the difference in pedal resistance expected?

2) Can the resistance get stiffer over time?

3) If so, why would that be? Is it possible that the pivot needs greasing/cleaning?

Any insight would be greatly appreciated.

Answer to Q1: Yes. Mine operates just as you described but I have chains.

Answer to Q2: I haven't owned mine long enough to tell. But just like you, I have on occasion become very conscience of the TW operation while taxing, taking off and landing. It could be because its dirty and dry (needs lubrication) I think its just because I'm paying more attention.

Answer to Q3: I know mine can use cleaning and lubrication. Actually, I order a new tail wheel from Flyboys, but its back ordered, still waiting.

Thanks for the post and replies. Helps me to better understand what I'm experiencing.

[vfrazier]

Yes, clean and grease regularly... about every 6 months, or at condition inspection, depending on hours flown and how much dirt/grit you encounter.

And disassemble and clean it regardless of whose tailwheel you're using. ALL of them require disassembly to properly clean and grease the locking pin mechanism. (Yes, ALL of them!!!)

Any light grease is fine. Lubriplate works well. Wheel bearing grease is OK, but excessively heavy grease might prevent the pin from moving properly. Even motor oil is OK in a pinch.

Keep in mind also, the lubrication is protecting the steel parts from rusting AND providing lubrication. So, check it periodically!

Replace any worn parts. Pay particular attention to the locking pin/control arm interface.... where the steering action comes from!!!! If it doesn't work right... fix it!

[DartDriver]

Originally Posted by vfrazier

Yes, clean and grease regularly... about every 6 months, or at condition inspection, depending on hours flown and how much dirt/grit you encounter.

And disassemble and clean it regardless of whose tailwheel you're using. ALL of them require disassembly to properly clean and grease the locking pin mechanism. (Yes, ALL of them!!!)

Any light grease is fine. Lubriplate works well. Wheel bearing grease is OK, but excessively heavy grease might prevent the pin from moving properly. Even motor oil is OK in a pinch.

Keep in mind also, the lubrication is protecting the steel parts from rusting AND providing lubrication. So, check it periodically!

Replace any worn parts. Pay particular attention to the locking pin/control arm interface.... where the steering action comes from!!!! If it doesn't work right... fix it!

I've read all the posts on tailwheel lubrication, and all the great advice to keep it well lubricated. Just to put a point on this, let me add that a ground loop is the likely outcome if you don't keep that tailwheel maintained properly. I was lucky my first 180 hours with my RV-8 ... very intermittently I'd lose the tailwheel lock, but it never bit me. Then, last week flying into Catalina Island, the accident chain happened:

1. Unexpected weather caused me to land downhill with an 8 knot left cross.
2. 3000' runway (with cliffs on both ends) increased the pucker factor.
3. An unlocked tailwheel caused me to exit the 75' wide runway 1500 feet down on the left side (doing about 15 knots).
4. Groundlooped in the gravel and dirt, coming to rest 20' from a small fence in front of a cliff.
5. Right Grove airfoil gear was bent an additional 25 degrees just above the wheel, as well as the outboard attachment bolts getting ripped out.
6. A $6k bill.

Reasons:
1. There was some old paint in the slot where the locking pin slid into...just enough material to give me an intermittent problem.
2. I never recognized the seriousness of the intermittent tailwheel not-locking problem, so I never investigated this forum to nail down the serious nature of the failure.
3. A total lack of appreciation for how an unlocked tailwheel could ruin my day.

Silver Linings:
1. 8-day vacation in Avalon, Santa Catalina Island.
2. Adventure brought me closer to my son-in-law Zach (who was in the back seat).
3. Got to know Curt Norton, a CFI and A&P who came out from Riverside to help me install new gear.
4. Got to know Justin Bollum, the airport manager at KAVX, his assistant Dennis, and all the great staff at "Airport in the Sky".

So I'd like to foot-stomp the advice above:
1. Know your tailwheel.
2. Lub it at every oil change (and make sure the working parts are clean, smooth, and don't have any contamitants like old paint).
3. And perhaps more importantly, figure out intermittent failures before they put you in the dirt!

Also, thanks to all who contribute to this forum ... you've helped me a great deal over the years.