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Notice just added to Factory site: (FF-1207)

Bob,

Do any of your structural engineer friends know the mean friction factor (or sometimes called the nut factor) if Loctite 242 or 243 is applied? (The nut factor for the dry case is usually assumed to be 0,2) I can find Loctite information for other grades of Loctite but not for 242 or 243 (the blue's). There is a lot of contradictory information on the web. Some of the websites indicate it is an adhesive, some indicate it is a lubricant, and some indicate it is neutral before it sets up.

Sorry Marty, but Loctite is not something we use in structural engineering.

However here's a link to a datasheet for Loctite 242 I found, although you've probably come across it already. It's described as an adhesive (once it has cured), but it will obviously act as a lubricant initially while you're tightening the bolts.

http://www.sjgogo.com/pdf/242-en.pdf

The data sheet does mention lubricity, but also says that for critical applications you should do some testing. I'd suggest contacting Henkel for further information, although while they might give you some general guidance on friction factors for their products, I'm sure they wouldn't advise on any specific application.

If there are any mechanical engineers here, they should know more about this subject than I do, and may be able to comment. I just know enough to be careful. Hopefully Vans or Rotax will look into this issue and come up with some recommendations for all of us in due course. Until then, I suspect we're on our own.

Rob
 
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Erich,

SORRY but red may have been a BIG mistake. Please read all of the previous posts regarding the effects Loctite has on the capscrew and the threads in the engine block with respect to the pre-load applied.

Adding Loctite is NOT a simple science. An engineering solution is really required before the general population jumps at a solution.

The only thing I've seen in this thread regarding the loctite is ensuring you get the proper torque (which we dont actually know yet) because it could be either a lubricant or adhesive before being torqued.

Since it worked for Larry using blue (and I believe that blue and red are fairly similar before curing), I suspect that the actual torquing down of the bolts should be alright. In my case, the bolts were already torqued and torque-sealed. I pulled them, applied loctite and retorqued, and the torque seal ended up lining up again.

My conclusion from that was that the loctite was reasonably neutral as far as changing torque goes.
 
Service Notification

Marty, I went there, but I must be blind. Can't find any reference to this mod.

Tom
 
Letters and Notices

Look under Letters and Notices. Nov 19,2010 - RV-12 PowerPlant Kit - FF-1207 Cooling Shroud Modification.
 
But still nothing

on how to keep the bolts from coming loose or how often to take a look at them! Which is what we're really interested in seeing

Wayne 120241/143WM
 
Finished the mod...

I finished the mod on the shroud over the weekend. All 4 of my bolts were still tight at 26 ft-lbs but I only have 21 hours on the plane. Still find it hard to imagine that they would remain tight for the first 20 hours and then loosen later. Did anyone else who discovered loose bolts beyond 25 hours of flight time actually check them at 25 hours and confirm they were tight at that point? Given the lack of accessibility, I am guessing most had not been checked?

A couple other things. I found the ball-end wrench to work quite well (I know there was some concern about damaging the head of the bolt). And while I did not try removing the left upper bolt, I will rescind my previous speculation that the mod would provide enough clearance for bolt removal. I now doubt that it would.

Jeff
 
I Found It

Look under Letters and Notices. Nov 19,2010 - RV-12 PowerPlant Kit - FF-1207 Cooling Shroud Modification.

Thanks Tony. I was thinking that it would be on the top. I just didn't scroll down far enough to get to the notices.

Tom
 
Just catching up. Did not get to do my planned check on my engine bolts this past weekend as a kitchen floor project was assigned a higher priority by a girl I married a long time ago. I did get to talk with Lockwood's top Tech guy tho and his counsel is to use the blue Loctite AND keep the torque at 312 inch lbs. He feels the lower the torque that holds in an aluminum case , the better. Since some of you have reported the successful holding with the blue Loctite that makes sense. I know some have gone to the 360 in lbs, but not all unless I missed it in reading the posts. He also felt the lubricity provide by the Loctite would cause little if any additional torque on the bolts. Regarding the Nordloks he felt they were not necessary as the Loctite should do the job. I will check my bolts at the earliest opportunity (and before flying) and will provide results. I would appreciate any comments this information generates. Thanks.
Dick Seiders
 
Received an e mail from Rotax Tech today stating that after his discussing the torque issue with Van's today the 312 in.lbs was in error per Vans so Rotax says go with the 360 in.lbs. per Rotax specs. He did not mention the blue Loctite, but in view of his earlier statement I would presume the blue would be used in conjunction with the 360 in.lbs. torque level.
Dick Seiders
 
Bolts slightly loose at 20 hours

My apologies for posting twice but wanted to get this out.

Just finished checking the bolts and modifying the engine shroud on N143WM at 20.1 hours.
All bolts were torqued to 310 in-lb PER THE RV-12 MANUAL at installation. At 20.1 hours all bolts required 10-15 deg of turn to go back to 310 in-lbs. I removed all the bolts, inspected them, coated them with lots of blue Loctite 243, reinstalled them and torqued them to 360 in-lb. All bolts were torque marked so I can see if they've moved at "regular" intervals, whatever "regular" comes to mean. I increased the size of the slot in the shroud so the upper left bolt could be removed. I did not remove the powder coating inside the mount since it hadn't been mentioned at the time and I'm not sure how it can be done with the engine in place.

After removing the lower right bolt it could not be reinstalled until enough pressure was put on ther arm of the mount to flex it down almost 1/16 inch. A friend whose entire career at Wright-Pat says that the problem is due to something in the structure flexing in the right way to set up a resonant frequency-- possible the lower right motor mount arm? That's the only bolt that did not go right back in.

The real problem, and one I'd think the whole LSA community would be VERY concerned about, is that the ONLY structural fasteners in the whole airplane that DO NOT have self-locking nuts, cotter pins, or safety wires are the 4 bolts holding the engine on! Is that ASTM standards??? If so, then I think the first time the FAA finds the engine of an RV-12 a half-mile from the crumpled wreckage, the result will make the CH-601 ruckus look insignificant!

My feeling is that the real solution may be a re-designed motor mount with a way to safety those 4 bolts.


Wayne 120241/N143WM
 
Pictures of cooling shroud mod

I am a little late completing the mod to the cooling shroud to access the upper left engine mounting bolt due to other priorities, but here are pics of how I made access to the bolt. I tried to incorporate the best ideas of those who had already done it and posted their results.
Here is the area prepped for surgery:
1132931483_Qk89v-M.jpg

The cuts made with a hacksaw blade trimmed to a point:
1132931686_jJQqs-M.jpg

A tab with a nutplate added:
1132932020_7wr6N-M.jpg

The cap with locating tabs:
1132932294_QWLPW-M.jpg

Done:
1132932412_MzxeX-M.jpg

I found the bolt still tight at 26 ft-lb as installed originally. Removed it and retorqued with a Nord-loc washer to 30 ft-lb.
Tony
 
Tony,
How many hours did you have when you retorqued. It appears as though the bolts didn't loosen from original setting.

Gary
 
An elegant solution

Thanks for the pictures of how you solved the upper left bolt accessibility problem. It's the best one yet - simple and well engineered.

You 'leaders' in the after prototype development of the RV-12 should be on Van's payroll - if not $$$, then a few 'atta boys' from Van's have been earned. Whether or not that happens, you have the admiration and appreciation from us 'followers'. Thanks again.:cool:
 
Tony,
How many hours did you have when you retorqued. It appears as though the bolts didn't loosen from original setting.

Gary

My 12 had 45 hours at this time. The top left bolt was the only one tight. The top right took 30? rotation to 26 ft-lb. The bottom left was about 1 turn loose. The bottom right was completely loose and almost lost.

Tony
 
Tony, you sure do nice work! I finished my mod last Saturday, but found Van's suggestion to make a patch to glas over the groove very awkward to do. After failing twice to get a good fit using the patch method I decided to sand the epoxy shroud at the slot I cut out and simply lay up the patch directly onto the slot using epoxy resin. Worked like a charm, and a lot less work. (sorry I don't have pictures sometime you'll have to tell me how to do that). As reported earlier the bolts were all at the 312in lbs as originally set except for the upper left which moved about 1/16". Now torqued to 30 ft lbs, with blue Loctite, and torque sealed.
Dick Seiders
 
Is the problem solved?

For those of us without an RV-12, please explain the current status of this problem / issue.

I understand that a number of RV-12's had their engine bolts come loose. As far as I know, nobody had their engine actually fall off.

If I understand this notice, it's designed to allow the easier inspection of the engine bolts to see whether they're loose, and I suppose to allow them to be tightened if they are loose.

I remember that there was a lot of discussion of ways to keep bolts from coming loose. I don't remember if there was a definite statement from Van's regarding a change that would keep the bolts tight. Was there? If so, what is it?

If I were to buy a RV-12 kit now, should I feel assured that if I follow the plans I don't need to worry about my engine bolts?
 
Nothing official - -

Many of us have removed the bolts and put on plenty of BLUE Loctite, and they are doing well. I think it will prove to be a good fix. Going to 30# will help also, but the blue Loctite should give you a good solution. I would not worry then. Torque Seal them, and look at them every time the lower cowl is off, and you should be fine.

John Bender
 
Loctite

I spoke with a retired mechanic from a flightschool down south. They used the rotax on their lsa's .... Can't remember the airframe ... He advised that any install they did, they used the loctite on the cap bolts. Never had any issues
 
Van's fix

Here are a couple of pictures of the FF-1207 cooling shroud I received from Vans last week in my Engine Kit. It appears to have be fixed by Vans to allow access to the engine bolt. I'm not sure though since I haven't installed it yet. I'm still working on canopy fiberglass and will be until ??
Dec22-10001.jpg
Dec22-10002.jpg
 
Hey Steve, sorry to be a pain, but I can't tell much from your photos. Perhaps a shot of the entire glas shroud would make it more apparent.
Dick Seiders
 
Van's new cooling shroud cut out markings

It looks like Van's has copied Tony's cut out to me. See Tony's posting on the previous page.

Bob Kibby "N722BK" flying
 
Steve, thanks. I think I see it now. When you put it on the engine make sure you can get the bolt out before nailing everything down.
Dick Seiders
 
The new shroud

Actually, it doesn't look like the bolt could be removed with the new shroud in place. It looks like it would allow access to the bolt with a ball end allen key to check for tightness at the 25 and 100 hour engine check as listed in the Rotax checklist. I think that's all that is intended by the design. I can't really think of a reason to remove the bolt completely unless you wanted to put Loctite or a Nord-Loc washer on it after the fact, so best to do that on initial installation of the bolt, before installing the shroud.

Tony
 
Shall I assume the shroud will be modified on all new engine kits? And will Vans modify the mold when the current stock of shrouds has been exhausted?

Art Pennanen
 
Tony, I suspect you're correct in that the bolt doesn't need to be removed. Even if you wanted to loctite it you could likely loosen it enough to get sufficient loctite on the exposed threads. I felt that while I was doing the work to the original shroud I wanted to allow bolt removal as it is the only one of the four you can't get out, and if you ever have to well, you know you can.
Dick Seiders
 
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