Something that hasn't been talked about much recently is the tendency for RV tail wheels to break out easily, or refuse to lock into tail wheel steering mode. This used to get a fair amount of press on the various forums, and was usually blamed on burs developing on the corners of the spring-loaded plunger. Other reported causes include poor lubrication, dirt - the usual suspects when a mechanism refuses to operate properly. I finally have some photographic evidence of what I believe to be at least a major (if only one of several) cause of this behavior - wear in the steering arm itself.
Louise's RV-6 has exhibited a lack of steering lock in the "right" direction several times. I had it happen on my -8 as well. Each time this happened, we did the ritual cleaning and deburring of the plunger. I have also found that flipping the steering arm helps, although the "second side" doesn't last as long as the first. Replacing steering arms usually fixes the problem.
Several months ago, We replaced the Silver Bullet steering arm on Louise's plane with a spare that we had on hand, because I saw that the "U"-shaped cutout for the plunger was wearing out the sides. We had a spare chrome link on hand, and put that into service. Tonight, I had to change it again - this time to a spare Van's unit we had, as we don't have any more from Full Throttle (we have a couple on order, but we all know how that goes with Full throttle - not holding our breath...). Anyway, the following two pictures shows pretty conclusively the wear that we are seeing:
See the "shoulder" in the "U"-shaped cutout? That shouldn't be there! In fact, the shape of the shoulder is the original dimension of th cut-out - the open legs of the "U" should be parallel. in the worn out portions of the channel, they are pointing outwards - allowing the plunger to easily slip out,and the tail wheel to go into full-swivel mode. With a Van's arm, you can flip the arm and get a little more use out of it - but not for long, as the remaining amount of material wears very quickly. With the single-armed, chrome unit from Full Throttle, you don't have that choice - it can't be easily flipped. The fact that the spare unit we had from Full throttle wore out in less than half a year tells me that there might be a materials hardness problem, but since Louise's original lasted several years, I hate to call the problem generic.
At any rate, I was able to prove that with the worn unit, it took almost no effort to break the tail wheel loose by hand. With the new unit, I couldn't do it without the typical sharp push on the fuselage. If you're tail wheel isn't locking in to place, remove and inspect the arm very carefully - you might find the problem right there, before digging deeper into the spring plunger (and sending it shooting across the hangar.....)
Paul
Louise's RV-6 has exhibited a lack of steering lock in the "right" direction several times. I had it happen on my -8 as well. Each time this happened, we did the ritual cleaning and deburring of the plunger. I have also found that flipping the steering arm helps, although the "second side" doesn't last as long as the first. Replacing steering arms usually fixes the problem.
Several months ago, We replaced the Silver Bullet steering arm on Louise's plane with a spare that we had on hand, because I saw that the "U"-shaped cutout for the plunger was wearing out the sides. We had a spare chrome link on hand, and put that into service. Tonight, I had to change it again - this time to a spare Van's unit we had, as we don't have any more from Full Throttle (we have a couple on order, but we all know how that goes with Full throttle - not holding our breath...). Anyway, the following two pictures shows pretty conclusively the wear that we are seeing:
See the "shoulder" in the "U"-shaped cutout? That shouldn't be there! In fact, the shape of the shoulder is the original dimension of th cut-out - the open legs of the "U" should be parallel. in the worn out portions of the channel, they are pointing outwards - allowing the plunger to easily slip out,and the tail wheel to go into full-swivel mode. With a Van's arm, you can flip the arm and get a little more use out of it - but not for long, as the remaining amount of material wears very quickly. With the single-armed, chrome unit from Full Throttle, you don't have that choice - it can't be easily flipped. The fact that the spare unit we had from Full throttle wore out in less than half a year tells me that there might be a materials hardness problem, but since Louise's original lasted several years, I hate to call the problem generic.
At any rate, I was able to prove that with the worn unit, it took almost no effort to break the tail wheel loose by hand. With the new unit, I couldn't do it without the typical sharp push on the fuselage. If you're tail wheel isn't locking in to place, remove and inspect the arm very carefully - you might find the problem right there, before digging deeper into the spring plunger (and sending it shooting across the hangar.....)
Paul
