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SERVICE BULLETIN 16-08-01 (released Oct 1, 2016)

DeltaRomeo

doug reeves: unfluencer
Staff member
Date Released: October 1st, 2016
Date Effective: October 1st, 2016
Subject: Stabilator Bearing Inspection
Affected Models: All RV-12 w/ Emp/Tailcone Kits delivered prior to August 1, 2016
All SLSA RV-12 aircraft delivered prior to August 1, 2016
Required Action: Inspect stabilator bearing security
Time of Compliance: Before further flight (Step 1 and Step 2)
During each preflight inspection (Step 1)
At each annual condition/100 hour inspection thereafter (Step 2).

continue:
http://www.vansaircraft.com/pdf/sb16-08-01.pdf
 
Wouldn't it be nice if Van's would post a video of exactly where the "flat wood" should be placed and then where the thumping should commence.
 
Wouldn't it be nice if Van's would post a video of exactly where the "flat wood" should be placed and then where the thumping should commence.

Pine, oak, spruce, I think we need some direction on the type of wood to be using for this SB.....
 
What’s the correct procedure if your tailcone kit shipped before August 1, 2016, but you haven’t riveted the VA-146 bearings to the F-1211B bulkhead doubler and F-1211-C hinge brackets? Are there “new and improved” VA-146 bearings we should order that don’t have this issue, or should we just apply Loctite 648 as described in the service bulletin? Or maybe there's a revision to the kit assembly instructions that we should follow?
 
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Wouldn't it be nice if Van's would post a video of exactly where the "flat wood" should be placed and then where the thumping should commence.

I think step 2 on the SB explains it fairly well, but maybe a sketch on the SB would be a good idea?
 
The purpose of the wood is to protect the stabilator from your hand and to protect your hand from sharp aluminum. The wood also evenly distributes the striking force to the stabilator. The wood should be placed near the end of the spar. The object of the test is to determine how much horizontal side to side play there is, and if the stabilator will move far enough to rub on the tail cone fairing. A pilot would not want the stabilator to become jammed.
During preflight inspections, a steady horizontal force can be applied to the end of the stabilator while moving it up and down, looking for any binding.
 
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My HS tested fine. Has anyone in the group found an issue with the bearings so far?
Alex
 
My HS tested fine. Has anyone in the group found an issue with the bearings so far?
Alex

No problem checking during my annual, but... I have some qualms about " five good ?thumps? with the palm of your hand". Is there not a risk to dislodge stabilator bearings that are perfectly fitted into their housing? Needless to say my "good thumps" were not that heart felt! Anyhow the clearance between stabilator and tailcone skin is so small on each side that I believe the preflight check should detect any offset through the swing inspection of the stabilator.
Let me know if I am wrong.
 
My skin distance from the screws on the tail cone fairing is pretty close. I had never experienced any clearance issues, and always check the movement of the stabilator during pre-flight. I followed this Service Bulletin and discovered a slight rubbing of the skin on the Rt. side skin and screw in the center of the fairing.

I did the "thumping" again and no slight scrapping. I emailed Vans support and they felt a slight movement would not cause a bearing replacement, but I should consider some skin relief near the screws with the close clearance. I had planned to do a little more relief at annual when I had the fairing off for inspection.
 
Alas, Poor N73HR

I ran the test-only took a whack or two to cause 1/8-th inch plus of displacement both ways. Removing and re-installing the horizontal stab--one of my favorite activities to allow me to review my favorite cuss words.
 
This year I noticed some play in my stabilator. I feared the worst, but when I took the stabilator off what I discovered was that the paint shop had not put the shim washers back in after they painted. The paint layer was thick enough to center the stabilator in the hinge bearing. Over 5 years the paint wore away and I ended up with the small horizontal play (about 3/32"). It was just enough to cause the stab skin to rub against one fairing screw.

So if you fail the "Thump Test" it may not be a slipped bearing.
 
Well, my bad! Mothership was right! I put the stabilator back on with the shim washers and the thump test failed again. I tapped the bearings with a nylon head tack hammer and they popped out. Looks like my well intentioned attempts to lubricate the joint only ended up wicking oil into the gap between the bearing and the socket it is pressed into.

I cleaned up everything with acetone and alcohol before applying the Loctite recommended in the SB. Hopefully the issue is resolved.
 
Well, my bad! Mothership was right! I put the stabilator back on with the shim washers and the thump test failed again. I tapped the bearings with a nylon head tack hammer and they popped out. Looks like my well intentioned attempts to lubricate the joint only ended up wicking oil into the gap between the bearing and the socket it is pressed into.

I cleaned up everything with acetone and alcohol before applying the Loctite recommended in the SB. Hopefully the issue is resolved.

Hi Rich,

Have the bearings been holding in place since you did the service bulletin? My kit is still under construction, and I'm just about to rivet the bearings into place. I've been debating whether to do the service bulletin on the bearings I have or just buy new bearings. The bearings that shipped with my kit seem pretty tight, but I wouldn't install them without complying with the service bulletin.

Has anyone else added Loctite per the service bulletin? How did it work out? The fit between the VA-146 flange and the bearing is so tight, it's hard to see how the bead of Loctite works its way in between them, but I guess it must wick into place.
 
Loctite retaining compound works great, at work we use it for bearings and press fit components that have tolerance stack up causing too loose of a fit. If it were me I'd put loctite on the bearings and rivet it. I don't see any reason not to.
 
stab bearings slipping

I actually had the bearings slip sideways enough to make the HS skin rub against the left side tailcone skin. It happened soon after assembly, before I even made my first flight. I whacked the end of the spar pretty hard with my hand to knock it back into place and then called builder support to ask for guidance. They told me to try the Locktite thing and after 67 hours it still is centered. I did file off the edges of the HS skin to get a little more clearance while I had it off. The SB sounds an awful lot like my phone conversation with builder support and was issued just a few weeks later.
 
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