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Re-rivet control horn bracket

Jyuma

Active Member
I was checking over my work on the empennage when much to my horror I discovered that I used the wrong rivets to attach the WD-01207-1 & the WD-01208-1 to the HS-01233 Brackets. I used POP rivets LP4-3 instead of AN470AD4-6.

If I could post pictures here I'd show you what I had to do to replace those rivets. Not only could I not get a drill in there to drill out the pop rivets, there was no way for me to get any of my hand squeezers in there to squeeze the AN470AD4-6 rivets.

Long story short... after fighting for an hour to get the pop rivets out, I stood the rear stabilator up on it's end so it was sticking 8 feet straight up and then I balanced my floor pneumatic squeezer on one of those 12" high foot stools Harbor freight sells... and then with the 9" throat on my floor squeezer I was able to squeeze the AN470AD4-6 rivets home. It actually worked out great, but would not have been necessary in the first place if I didn't use the wrong rivet to begin with.

Lesson learned... double and triple check everything you think you know well about what the plans are telling you to do.
 
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If it?s true confession time I admit an acquired skill at removing the wrong rivet!😜

Good one. :)

But now it's confession time again, and this time I'm afraid I might not be quite as lucky.

I sent the following email to Vans support but I haven't received a response yet...

On page 9is/U-04 of the empennage kit, Figure 2 shows riveting the WD-1222 to the HS-01203-1 using AN470AD4-5 rivets. I somehow missed that note and used the LP4-3 blind rivets instead.

The entire stabilator is complete and I have no way of changing those rivets with the correct ones short of completely disassembling the stabilator.

Please tell me it?s ok as is or there is a corrective action that doesn?t require disassembly of the entire stabilator.
 
Ouch. (drawing below so everyone understands). Best case is that Van's MAY ok drilling out the LP4-5 and have you use CherryMax CR3213-4-xxx -- which may be 4-2 (grip range .063-.125) or 4-3 (grip range .126 - .187) instead of the AD4-5's (grip range .114 - .134) .. I'm not sure of the actual material thickness there.

I'd move on to the next section while you wait to hear from the mothership.

sparbox.png
 
Ouch. (drawing below so everyone understands). Best case is that Van's MAY ok drilling out the LP4-5 and have you use CherryMax CR3213-4-xxx -- which may be 4-2 (grip range .063-.125) or 4-3 (grip range .126 - .187) instead of the AD4-5's (grip range .114 - .134) .. I'm not sure of the actual material thickness there.

I'd move on to the next section while you wait to hear from the mothership.

sparbox.png

Thanks you your input... it is greatly appreciated.

There is no next section for me to go on with... I've completed the empennage kit, I even have the fiberglass work on the rudder and Vertical stabilizer done.

I was just rechecking my work after seeing some of the notices about cracks in the stabilator hinge brackets when I noticed some of the pictures in the RV-12 Builders Blog showed a picture of the section in question and I noticed my rivets were different. I have no idea how I missed something so obvious. Brain fade is my only excuse.

I'm hoping the fact that the counter balance tube goes thru both WD-1222 counter balance brackets and then the tube gets secured to the brackets with two 3/16ths AN bolts and nuts. In other words, the brackets that hold the counter balance tube can't go anyplace once the counter balance tube is inserted without first shearing off 24 blind rivets (12 on each bracket). I would think that's near impossible but I won't let it go unless the mother ship says it's OK or gives me a workaround. I'd really hate to have to drill out about 1000 rivets.
 
Per page 17-3 of the RV-12 Maintenance Manual ?Cherry Max CR series rivets may be substituted for any AN470AD rivet or LP4 rivet.?. Looks like the best approved path forward.
 
Per page 17-3 of the RV-12 Maintenance Manual ?Cherry Max CR series rivets may be substituted for any AN470AD rivet or LP4 rivet.?. Looks like the best approved path forward.

Oh man... you just made my day.

Thank you.
 
Per page 17-3 of the RV-12 Maintenance Manual ?Cherry Max CR series rivets may be substituted for any AN470AD rivet or LP4 rivet.?. Looks like the best approved path forward.

Vans says no.

I can't find the RV-12 maintenance manual... it's not on the Vans site, at least not listed as RV-12 maintenance manual.

Could you please post the section your described.

Thank you
 
Holy cow... Vans support got back to me almost instantly on my followup question.

Here is what they said...

The engineers will accept the cherry but a pulled rivet has a higher tendency to work loose than driven rivet. The cherry rivets are also much more particular about hole size. These could be used in place of the 470 rivets providing your hole meet the required cherry rivet specifications for hole diameter.

So it looks like you were correct... the Cherry Max rivet is an acceptable substitute.

The only question I have left is which Cherry Max rivet to order. According to the charts I think I'll need a dash-3. The dash-3 has a clamping range of about .126 thru .187. The thickness of the WD-1222 is approx .090 and the HS-1203 spar is approx. .040 giving a total thickness of .130. Does that sound about right to you?

Thanks again for saving me countless days of rework.
 
Thanks. I'm guessing the support person checked with engineering and found that the Cherry Max is an acceptable substitute. That could be why I got an instantaneous response to my followup question.

This is a pretty critical joint that can get a fair amount of stress from forces on the elevator and opposed by the control system. I wouldn't too quickly write off their concerns about pull rivets working loose. In most applications I wouldn't think twice about it. However, I see this a pretty critical connection, as it directly ties the elevator to the control system.

Larry
 
This is a pretty critical joint that can get a fair amount of stress from forces on the elevator and opposed by the control system. I wouldn't too quickly write off their concerns about pull rivets working loose. In most applications I wouldn't think twice about it. However, I see this a pretty critical connection, as it directly ties the elevator to the control system.

Larry

Hi Larry

I think you may have misunderstood which connection we're talking about. The WD-1222's hold the counter balance tube, not the stabilator.

Also, the WD-1222 is getting riveted to the .040 aluminum of the HS-01203 spar, which is probably why there are 12 rivets each on the front and rear WD-1222's. How strong does a rivet need to be that is connecting something to an .040 piece of aluminum?

There is something that is a bit confusing to me though... The WD-1207-1 and the WD-1208-1 (the stabilator control horns) do carry the stress of the control cables moving the stabilator and those two brackets get riveted to the same spar as the WD-1222 but with BSPQ-5-2 blind rivets. The difference being that the WD-1222's get riveted before the spar tube is closed and therefore you have access to both ends of the rivet which means you can use an AN470. However, the WD-1207-1 and the WD-1208-1 don't get riveted until after the spar is formed into a box and there is no access to the shop head side of the rivet for squeezing, so a blind rivet or bolt into a nut plate would be your only options. The plans call for BSPQ-5-2 blind rivets for the stabilator horns. Curious.
 
Back in the old days (like 2 years ago), the control horns were ONLY attached to the sparbox by (4) AN3-4A bolts each. Then they found some cracking of the spar around those bolts.. so they came up with a retrofit for basically every RV-12 in the air (with the stabilator closed up)... my guess is it was simpler to take those same instructions and incorporate them into the KAI.. rather than come up with some sort of different plan that takes advantage of the open box.

I did that retrofit.. but.. I can't remember using any BSPQ's that weekend. mmm I'm going to have to review my directions now :confused:
 
Hi Larry

I think you may have misunderstood which connection we're talking about. The WD-1222's hold the counter balance tube, not the stabilator.

Also, the WD-1222 is getting riveted to the .040 aluminum of the HS-01203 spar, which is probably why there are 12 rivets each on the front and rear WD-1222's. How strong does a rivet need to be that is connecting something to an .040 piece of aluminum?

There is something that is a bit confusing to me though... The WD-1207-1 and the WD-1208-1 (the stabilator control horns) do carry the stress of the control cables moving the stabilator and those two brackets get riveted to the same spar as the WD-1222 but with BSPQ-5-2 blind rivets. The difference being that the WD-1222's get riveted before the spar tube is closed and therefore you have access to both ends of the rivet which means you can use an AN470. However, the WD-1207-1 and the WD-1208-1 don't get riveted until after the spar is formed into a box and there is no access to the shop head side of the rivet for squeezing, so a blind rivet or bolt into a nut plate would be your only options. The plans call for BSPQ-5-2 blind rivets for the stabilator horns. Curious.

Sorry, I thought this was the elevator horn attachment.

Larry
 
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