What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

SB 18-02-02 Potential cracking in the horizontal stabilator front spar

just finished today. Not mentioned in the instructions is the potential for interference between the top tailbone fairing and the gusset at full displacement of the stabilator. Mine did interfere and I had to file an eighth of an inch of the fairing above the gusset.
On the last page of the SB.... I guess you missed it.


Install the F-1294A and F-1294B Upper and Lower Tailcone Fairings and check for clearance at extremes of travel. See KAI Section 12


It is assumed that if you discover interference that you will correct it to gain the clearance described in Section 12
 
I finished the mod today, and now need to reinstall the stabilator. I see what you mean, John. The gussets would be tough if not impossible to install after the stab is back on. I really hate messing with those hinge bolts. They are extremely frustrating to put in.
 
I finished the mod today, and now need to reinstall the stabilator. I see what you mean, John. The gussets would be tough if not impossible to install after the stab is back on. I really hate messing with those hinge bolts. They are extremely frustrating to put in.

My neighbor has one of these: https://www.harborfreight.com/catal...,EAFeatured+Weight,f,Sale+Rank,f&q=lift+table

Makes is pretty easy to install. If he didn't have one, I buy one just for this operation!

Jim
 
I finished the mod today, and now need to reinstall the stabilator. I see what you mean, John. The gussets would be tough if not impossible to install after the stab is back on. I really hate messing with those hinge bolts. They are extremely frustrating to put in.

Ah yes, I remember those bolts from the build! As I recall, one technique I used was to clean the parts real good and then super glue the washers in place until I could slide the bolts in. Just don?t get the glue on your fingers!

As to the table, I reckon one of the adjustable tables would be nice, but one can achieve almost the same result with a small table and various thicknesses of blankets, pads, etc.

I?m in no big hurry to start this project. Sure am looking forward to it though! 😫
 
Vans

On the last page of the SB.... I guess you missed it.


Install the F-1294A and F-1294B Upper and Lower Tailcone Fairings and check for clearance at extremes of travel. See KAI Section 12


It is assumed that if you discover interference that you will correct it to gain the clearance described in Section 12

As usual you guys at Vans are very thorough Scott. Thanks
 
Has anybody else had to replace the spacers (stabilator stops) between the bearing bracket halves with longer ones after installing the fix kit? My old spacers were approximately 1/16’’ short.
Alex
 
Last edited:
I got the stab back on today and the end of travel seemed ?squishy?. Then I realized the issue brought up here about the fairing interference was the problem. The fairing was stopping the stab travel before it hit the hard stop. This blog is worth it?s weight in gold!
 
Just finished both SB?s for my tail feathers yesterday....now for the fun of reinstalling everything. Will say, I appreciate Van?s for the continued support of our Aircraft.

Timing is everything...as this completes my annual for the tail section😜
 
Installing stabilator cable solo

Just finished this up today and it probably took closer to 16 hours than 6. I prepped, primed and painted all parts before disassembly of the tail. No real pitfalls until reassembly.

Then spent hours getting the pivot bolts and spacing washers in. The newly boxed in structure makes access much more challenging and only from underneath. Connecting the stabilator cable tensioner solo is extremely challenging but I eventually worked out a way to do it solo. Connect the top, pull the lower cable as far forward as possible, wrap tape around the clevis body and clamp lightly with vice grips from the bottom. Insert a piece of cardboard at rear bulkhead to protect it from the vice grips. (the vice grips will push against the bulkhead and lock the lower cable position) With your right hand use the tail leverage to match holes by pulling down on the rear of the stabilator. When aligned insert a short #3 bolt in from the trim motor side. Then slowly from the right work in the correct bolt to the right clevis side to put in the spacer washer and then to the left to install washer followed by outside washer and castle nut/counter pin. Probably is impossible solo to pull the cable tension directly from the clevis and put in the bolt.

Also plan on a lot of trimming to the top rear fuselage cap faring if built per plans. The exposed plates are notched but the notch ends probably 3/8" farther to the front than the clearance previously required for the box spar. Bottom is easy, just the plate thickness.
 
I got the bolts in from the top using forceps to get them into the hole. I set up my endoscope so I had a good view to manipulate the bolts. It also helps to chamfer the last 1/8? of the bolts so you can tap them into place. The spacing washers are a challenge. I used the endoscope to estimate the spacing with the stab centered. Then I pulled it off and super glued the washers in . It worked well, but it really hurt taking the stab off to do it after going through the gyrations to get it reattached to determine the spacing. The control cable turnbuckle locking clips are a pain because the alignment has to be perfect to form the groove for the locking pin.
 
We got the stab re-installed and cables reattached tonight. We'll need to install some washers between the brackets and bearings, but I'm pretty sure I'll be able to get them in with my washer wrench. I hope so, anyway.

There were no washers there before. Don't know why, maybe they weren't needed.
 
Just completed my Stab SB and offer a few observations on the stab reinstall:

1. Van's suggestion to instant-glue the original configuration washers to the new brackets worked great -- be sure to abrade the gluing surfaces for max adhesion and use a touch of grease to help the brackets/washers slide onto the bearings. CNC accuracy and Van's engineering are amazing in that my original washer configuration perfectly fit the new brackets/bearings.
2. Find two friends to help you position the stab. Alternatively, you can build up a table or sawhorses to get the stab in position -- the stab reinstall can then be a one-man job.
3. Forceps or long-handled needle-nose pliers working from below can be used to initially position the bearing bolts. A set of extensions for your socket set is necessary to final install and torque the two bearing bolts.
4. See Scott Millhouse's earlier post (#110) regarding the reinstallation of the stab cables -- that worked fine for me. Thanks Scott for the tip.
5. There is the potential to scrape the forward portion of the stab against the aft sides of the tail cone when you initially remove and replace the stab. Tape some protective sheet plastic or heavy paper in these areas to prevent scratching.

I wasn't looking forward to the stab reinstall but it took less than 30 minutes and went according to plan -- Yeah!
 
Last edited:
2. Find two friends to help you position the stab. Alternatively, you can build up a table or sawhorses to get the stab in position -- the stab reinstall can then be a one-man job.
One tip: We found that by putting the stabilator in place with the HS-1210 hinge stops contacting the F-1211C hinge bracket (upper or lower, whichever works for you), the bearing bracket holes were trivially easy to line up for the bolts to go in. It just puts the stabilator in the right position for everything to line up.
 
Hi Kevin, no detailed write up here, but I can tell you it took me about 12 hours, it involved more than I initially thought. Here is the completed image, this is the top view, the bottom is basically a mirror image of the gussets and the stabilator horn. Glad I did this before painting. You throw away the old hinge brackets assemblies.

2qdpzyg.jpg
 
My pleasure guys. Here is another one that may help. This is the bottom view. By the way, great to see your name Joe! It's been almost 2 years since your 'open house' at LVK, and your RV-12 was almost complete. I wondered what happened to you, hope all is well. Paul

2wlr85d.jpg
 
Several comments were made concerning the difficulty of inserting the spacing washers during the stabilizer install.

Ref: SB-18-02-02
Step 4: Taking note of the washers used between the Hinge Brackets and pivot Bearings for reuse later, disconnect the Stabilator Assembly from the Tailcone Assembly as shown in KAI Page 10-05 and KAI Page 11-03.

Refer to the KAI references above, it will instruct you during the assembly process to bond the washers to the inside of the bracket assemblies. This will facilitate an easier stabilizer install. Then all you have to mess with is aligning each bracket assembly with its respective bearing then insert the hinge bolts.

I'll be installing the stab tomorrow.. Just hope I don't have to mess with the turnbuckles.

Regards,
 
Last edited:
HS Brackets & Nutplate

In Step 19 of the SB it says to rivet a K1000-4 nutplate to the HS-1231A & HS-1231B hinge bracket using two AN426AD3-4 rivets. It doesn't say to countersink the HS-1231A first for the rivet head. Is that an oversight? Thanks.
 
Regarding the horn doublers being added in the SB, I read this:

Step 8: Drill #40 the six locations marked on the WD-1207 Stabilator Horn into the HS-01232 Stabilator Horn Doubler and HS-1211 Spar Cap.


It's saying to drill #40 holes into the 6 marked locations in the horn and drill through the doubler as well as the spar cap? Since you are flush riveting the doublers from the bottom through the horn, you wouldn't want to drill into the spar cap right? The pictures in this thread seem consistent with my thoughts but the SB instructions confuse me.

Am I reading the instructions wrong for this step or are the instructions incorrect?

Tony Vitiello
Ballwin, MO
RV-12 ELSA
Tail kit in progress
ULS Fuse kit next
 
Last edited:
Am I reading the instructions wrong for this step or are the instructions incorrect?

I had the same confusion. I decided not to drill those 6 holes into the spar cap. I cleco'd everything in place and drilled the 6 holes thru the horn, just deep enough to mark the doubler, then took it apart and drilled the holes through, did the countersink and riveting, then installed them. I am guessing that Van's just decided it would be easier to drill right into the cap, even though the holes would not be used, 6 #40 holes into the cap is probably not a big deal (actually 12 holes if you count top and bottom horns). I just didn't want to do it that way. Hope that makes sense.
 
It's not a big deal. Consider them lightening holes. :)
It's easier to insure everything stays aligned to just drill them while on the spar.

Vic
 
I drilled 2 all the way through to get good alignment then finished drilled the others off the spar. Worked well for me at final installation.
 
Thanks for the replies. Sounds like there are multiple ways to accomplish this as long as everything stays aligned.

One other question. I?m doing this SB on a new build, not after the fact as most are. Therefore my spar assembly is only clecoed at this point so I can disassemble to debur holes and clean chips inside the spar cap.

I?m curious about leaving burrs or chips inside parts you can?t access. I guess it?s just something you have to do and not worry about chips loose inside parts in cases like this? I suppose you can debur holes from the outside but how would you remove metal shavings?

I?ve had this issue when I have the rudder skins mostly riveted and have to slightly ream out matched holes to insert a pulled rivet. I use a #30 reamer and go really slow to minimize chips/burrs but still get a few shavings on the bottom side of the hole.

I haven?t yet had to drill out a rivet that I couldn?t access the stem but it will probably drive me crazy if I have to leave a rivet stem inside my wing or something.
 
I hear you Tony! I had to re-rivet one of the anti-servo hinges and ended up with the rivet tails inside the stabilitor. I cleared them out with a magnet on a long stick and a LOT of fishing around. It was a real PIA. :mad:
 
I opted to substitute a solid AN4 rivet for one of the LP4-3 on the HS-01231C Hinge Gusset mainly to keep up appearances.

You will need to temporarily remove the AN3 bolt on the Hinge Bracket Assembly to allow access for rivet squeezer.
-
eb7ers.png

-
33ktzj5.png
 
Last edited:
Installing the Stabilator is a Royal Pain...

I finished SB 18-02-02 and yesterday finally had warm enough temps to allow reinstalling the Stabilator. I followed KAI Page 11-03 instructions for attaching the Stabilator Assembly to the Tail Cone Assembly which details gluing the AN960-416 (OR -416L) washers to the Stabilator Assembly Hinge Brackets. I chose new -416 thin washers and scuffed the surfaces before gluing with super glue.

I had a problem trying to guide the Hinge Brackets over the Pivot Bearings. In my case the bearing inner race would dislodge one of the four washers with each try. The top and bottom U-shaped stiffener plates added to the new hinge brackets severely restrict access for hand placing these washers during reassembly.

My solution was to substitute a larger washer with more surface area for gluing. McMaster-Carr has a 316 Stainless Steel washer 1?OD x 0.281 ID x 0.040 thick. Hole diameter for AN960-416 is 0.265 so this larger washer has hole oversize by 0.016 so you need to center the washer over the hole in the Hinge Bracket when gluing. The new washer clamps the bearing inner race when tightening the assembly so no problem there. You will have to file two flats on the Stainless Steel washers for the outboard Hinge Brackets to clear the T-nut rivets.

A lot of folks have said that installing the Stabilator is a royal pain. With four of these large Stainless Steel washers glued to the Hinge Brackets the Stabilator slide onto the Pivot Bearings like a charm.

My 12 is licensed ELSA so substituting these washers is at my discretion. SLSA will need to follow the SB to the letter.

Disregard old Hinge Bracket and short AN bolt in photo?
-
2nlfk9v.png

-
biw9cz.png
 
I'd definitely call and ask about it. They shipped mine in less than a week.

As an update, I contacted Van's. Many orders have been backordered (including mine). I was told that more would be shipping in a week, so hopefully my order is included in that shipment.
 
Good report

I finished SB 18-02-02 and yesterday finally had warm enough temps to allow reinstalling the Stabilator. I followed KAI Page 11-03 instructions for attaching the Stabilator Assembly to the Tail Cone Assembly which details gluing the AN960-416 (OR -416L) washers to the Stabilator Assembly Hinge Brackets. I chose new -416 thin washers and scuffed the surfaces before gluing with super glue.

I had a problem trying to guide the Hinge Brackets over the Pivot Bearings. In my case the bearing inner race would dislodge one of the four washers with each try. The top and bottom U-shaped stiffener plates added to the new hinge brackets severely restrict access for hand placing these washers during reassembly.

My solution was to substitute a larger washer with more surface area for gluing. McMaster-Carr has a 316 Stainless Steel washer 1?OD x 0.281 ID x 0.040 thick. Hole diameter for AN960-416 is 0.265 so this larger washer has hole oversize by 0.016 so you need to center the washer over the hole in the Hinge Bracket when gluing. The new washer clamps the bearing inner race when tightening the assembly so no problem there. You will have to file two flats on the Stainless Steel washers for the outboard Hinge Brackets to clear the T-nut rivets.

A lot of folks have said that installing the Stabilator is a royal pain. With four of these large Stainless Steel washers glued to the Hinge Brackets the Stabilator slide onto the Pivot Bearings like a charm.

My 12 is licensed ELSA so substituting these washers is at my discretion. SLSA will need to follow the SB to the letter.

Great tip Jim, Thanks
 
I guess I might be a bit concerned about potential galvanic reaction with the mix of aluminum /steel / stainless but I can't say for sure. I used a piece of thin but stiff plastic sheet bent over each bearing (with a dab of grease) to guide the brackets into place without excessively molesting the glued washers -- then pulled out the plastic sheet and inserted the bolts.

ps -- Another tip: Before you remove the tail cone, temporarily position the four skin gussets in place on the stab and mark how much of the tail cone openings you will need to trim. Doing this in advance will save you from having to reinstall / mark / trim / reinstall the tail cone a second time.
 
Last edited:
David

Your point is well taken. I hadn’t considered the possibility of dissimilar metals, thinking Stainless Steel would be impervious to corrosion.

It’s been a very long time since I took a metallurgy class in college. I found a Galvanic Corrosion Chart listing 316 SS and a 2017 tempered aluminum alloy (Van’s uses 2024 alclad aluminum). The interaction doesn’t appear too bad if the 316 SS is in active state. Looks not so good if in passive state. Unfortunately that’s about as much as I’ve been able to glean. Perhaps a real metallurgist can comment. I have painted the aluminum Hinge Bracket first with Zinc Chromate and then gloss white urethane so chance of interaction is further reduced.

Zinc plated AN steel washer/bolt and aluminum looks like no problem.
-
2wq60ba.png
 
My take would be that by scuffing the SS washers and alum brackets and glueing them together the SS at the interface would stay in the active state. Especially if the assembly is primed. It looks like the aluminum would still be slightly sacrificial but for a corrosion cell to form there would have to be an electrolyte present.
Anxious to see where this thread goes...
 
It looks like the aluminum would still be slightly sacrificial but for a corrosion cell to form there would have to be an electrolyte present.

Tony, you live by the ocean, so salt air with lots of rain in the PNW would be a consideration...
 
Seems like steel and aluminum are in contact at many points in an aircraft. I?ve never heard of it being a problem. Has anyone else?
 
Cracks

All of the posts and pictures are very helpful. I have not started mine yet. I am wondering how many owners have actually found cracks after doing the inspection?

Thanks.
 
Removing rivet stems

I hear you Tony! I had to re-rivet one of the anti-servo hinges and ended up with the rivet tails inside the stabilitor. I cleared them out with a magnet on a long stick and a LOT of fishing around. It was a real PIA. :mad:

Has anyone found an easy way to remove the rivet stems after drilling out the rivets for the service bulletin? Amazon.com has several magnetic pickup tools that look like they might be helpful. Has anyone tried one?

Thanks,
 
while one of us rotated the HS around the other caught the moving remnants... took 5 minutes...not a big deal
 
I installed the stabilator fiberglass tips at the same time. With the end ribs removed I tipped the H.S. on to the leading edge so the rivets went to the front and then up on end and out the rivets fell out.
 
Thanks to a skilled builder, Tom Delaney, another completion. With his able assistance the project took us 14 hours only because of me tromping around. But as they say time flys when you are having fun.

All tips in this thread were useful. We stacked some boxes and cushions on two HF rolling carts and lashed the HS down to work on it, turned it over and same. Then slid it back into place and one person pushed up a 1/2 inch and forward, and the other used a modified/tapered bolt to align the hole and pulled it out with the other guy holding it up from below and the bolt with a little jiggle went in easily on both sides. Only knocked one washer loose but used a washer wrench on it rather than start over glueing..saw evidence where previous owners used some kind of thin looking masking tape to afix the washers. I think the idea is to push the bolts through the taped washers and leave it lay. I guess it worked and so did the super glue unless they get knocked around during reassembly/alignment. Then again maybe the tape would take a knocking better? Not sure.

Other than lucking out with a skilled assistant and this great web site with all the tips, I can’t image anything to add except ENJOY this little confidence building project.

V/r Doug
 
Last edited:
Back
Top