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IE; VA146 replacement, and Bearing DW4K2X ? Tom |
The text in the SB says "If a bearing and flange becomes damaged order a ?VA-146 Flange Bearing? for replacement. If
you wish to just replace the bearing order ?BEARING DW4K2X? for replacement. The bearing with flange is the VA-146 part #. The flange is what the bearing is a press fit into, and what you are loctiting it into if it is found to be loose. This can be seen in the KAI Section for the tail cone. So the Bearing part # is for just the bearing... should you need to replace just that portion (got loctite into it, etc.). If the SB work is completed properly, you should not need either part. |
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Still unclear on SB 16-08-01
I know, wrong thread, but the questions have come up here and it is pertinent if the stab is removed for SB 8-02-02
If the bearing is not loose then you don't have to fix anything, but will still have to bang on the stab ends at each annual and make a logbook entry that satisfies SB 16-08-01. Plus, the bearing could become loose at some time in the near future, especially with all that pounding back and forth, and the stab would have to come off again! BTW, how do the guys with fiberglass stab tips bang on those tips to satisfy the SB? So fixing the bearing while the stab is off makes a lot of sense -- to me anyway. Questions are: How to tell if the bearing itself is bad and then just order the bearing and the green Loctite? Why green Loctite, isn't that the one that wicks in without disassembling the parts? If you damage something and order the VA-146, I assume the bearing comes pressed into the flange but is it Loctited in? Apparently the original VA-146 were not Loctited, that is why they can come loose. If the VA-146 is now Loctited, should it not have a part number suffix indicating it is different than original? |
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The VA-146 used to be assembled by an outside vendor in which a quality control problem developed, so production was brought in house. The use of the loctite as an alternate method of bearing retention when one is found to not be as tight as desired, to avoid needing to replace the bearing flange which would be a big job. People do use the green loctite by letting it wick between parts in some situations, but that is not what Loctites installation requirements say is acceptable. Tests were done, to see if wicking it from the outside would be sufficient. It wasn't. |
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I have the fiberglass tips on order and was going to install them at the same time I'm doing SB 18-02-02 and SB 18-02-03. Looks like I might be going through the loctite process on the stab bearings also, if I'm going to install the tips. All this on a plane that isn't even flying yet! Oh well! Jim PS: Just read the procedure in the "Maintenance Manual" for loctiting (is that a word) the bearing into the housing. Doesn't seem like too big a deal and will solve the stabilator tip issue. |
SB 18-02-02 and SB 18-02-03 parts backordered
Van's sent out email indicating that both these service bulletin fix-um-up kits are now out of stock, and delayed until March 5th. I did receive the SB 18-02-03 kit today, but no such luck on the SB 18-02-02 kit.
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Found a crack
120323 290 hours on the Hobbs. I had not applied dye penetrant before but had watched the application on larger part.
Facing forward, it was at the right outboard hinge bracket, upper bolt nutplate, inboard rivet. It was about 1/8 inch and went into or came out from under the rivet. The good news is I need only one stop drill whereas it appears to me the SB example would need two. I needed the dye to see it. In fact, I missed it the first time with the dye but was not satisfied with the developer cover, too thick I thought. Since it was a tight area, the spray dye was too much and is probably still wicking down the spar toward the tip. I did spray it lightly. The next 3 or 4 times I wiped the dye on with a rag. Wiping on seemed effective as long as I kept the surface wet. Cleanup was much easier. Once I knew where the crack was, I could see it with a 10x loop or use the macro setting on the camera. I could not have found it without the dye. I tried it four times instead of three because when I wiped the third test, I could see the crack but could not see the end. On the fourth test, I center punched the spot with the dye and developer still showing the end, I hope. The servo tabs did not present a dye indication. |
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Some history on 120323
I built the airplane and have been the only one flying. From my -9A flying, I tend to keep the stick aft when taxiing. If there is wind, gusts or airplanes operating nearby, I tie the control stick. It certainly is possible that there were events where the controls were not tied, but it was not routine.
Of course, with fatigue, a single event could load the spar and initiate a fatigue crack. There are two ways that could be an issue. Of course, a gust lifting the tail would put the top stop into compression. Also, holding the stick aft while taxiing or landing would do the same. If initiated from the aft stick, there would also be a load couple between the stop and the upper control horn. Just some thoughts. I did not look closely at the stop bushings until I had removed them. Two are more heavily marked. I need to remove the paint to see if the bushing is marked. As you start to remove the brackets and bushing, document the condition of the bushings. |
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