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Attached are the tracings as well as photo of the arms.
I discovered that the area on the arms that make contact with the notch in the bolt have worn away. In fact a portion of the original flat surface is still evident and appear as small notches (ref the sketch for the left arm).
Man, we are REALLY going to need some good ones to work from. No wonder it wouldn't work right!
I have no doubt they could be welded and ground back, but ground back to where?
Hank
It is not as bad as it appears. I have attached another sketch which should clarify the amount of wear. As I see it, the notches on the tailwheel bolt are off-set (I have revised the sketch to show this as well as the area that needs to be built up). This allows the arms to clamp into the notches only when the tail wheel is in the trailing position. Hope the revised sketch clarifies.
Thank you for your input..............regards, bob
Here is a pic of a new Scott (Avox) steering arm. The surface that contacts the yoke shaft are perfectly straight. I didn't get a picture of the shaft but a new shaft is machined straight also with no break on the edges. The steel in the steering arms is relatively soft so it takes the majority of the wear.
I've also attached a scan of the Scott 2151 steering spring installation info. Note the requirement for 25-30 lbs. of tension.
Dan
Attached Files
Last edited by dmcneil; 04-26-2010, 11:29.
Reason: add attachments
Thank you for sharing this. It will be of great value in getting the arms to the correct shape.
As a side note, did you purchase the unit from AVOX? I gave up after a great amount of frustration and many phone calls. The last go-a-round they wanted the name of my company as well as have me set up an account with them before they would give me a quote. It would be good to know if they did have them in stock as well as the cost.
I've never tried to buy anything directly from Avox. They normally only sell through their distributors. I have gotten good technical assistance from them in the past. The steering arm in the photo came from Univair (I think... it's been a while).
To bring closure to the rebuild saga of the arm assembly I offer the following:
1. The dowels that hold the unit together are at a length that will be flush with the surface when burred. To remove the dowels I drilled enough to remove the burr on each.
2. A local welding shop built up the arms that allowed me to reshape them to the original design using my old tracings along with the use of the excellent photo of the new arm assembly that was provided.
3. It should be noted that there are 3 flat circular shims/spacers made of brass. one is situated between the arms and one inside each "cap" assembly.
4. I located the proper dowels at our local hardware store but they needed to be ground to the correct length to assure they were flush with the surface after burring. The dowel holes in the cap are very slightly countersunk to allow the slight burring of the dowels and allowing them to be flush with the surface.
5. My old arm did not have a grease fitting. I added one using a #3 drill and a 1/4-28 Zerk fitting.
The unit appears to be restored to the original functioning condition and I offer the above in case there are some out there that needs to consider a rebuild rather than spending big $ for a new one. BTW, I ordered a new arm from Univair at a cost of $333.00.
I know a lot of people are very brand loyal to Scott Tailwheels. But I would like to toot my horn in defense of the Maule Tailwheel. I am glad you were able to repair your tailwheel and get back into the air. And I don't mean to undermine your efforts. But I think I would be negligent as a fellow aircraft owner, if I didn't point out that you can buy a complete brand new Maule Tailwheel for $395. This is the model with the 8" pneumatic tire. The solid tire version is $388. I have had a Maule Tailwheel on my plane since I bought it and I love it. I had a similar problem with it not locking up. It uses a different mechanism to cause it to lock. I had to disassemble it and build up a portion with weld. Total cost was zero.
Thank you for sharing. In the future I will probably go with the Maule. The only question is the weight difference if any. Does the Maule weigh more than the Scott 2000 and if so does it affect the aft CG any appreciable amount?
I don't know what the weights of the two tailwheels are. I am sure that with some research on the two manufacturers websites, you could compare them. Possibly one of the supply houses might have info on the weights.
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