VAF Forums

VAF Forums (https://vansairforce.net/community/index.php)
-   RV-12/RV-12iS (https://vansairforce.net/community/forumdisplay.php?f=73)
-   -   RV-12: Engine Mounting Cap Screws Inspection (https://vansairforce.net/community/showthread.php?t=65020)

Tony_T 12-04-2010 07:07 PM

Finished the "easy three", using Nord-Locs
 
About 3 weeks ago I found my bottom right was almost out and lost. The bottom left was about 1 turn from tight. I replaced the bottom two bolts dry and clean using the carbon steel Nord-Loc washers and no Lock-Tite. Because I wanted to get on the upper right bolt with a regular allen socket, like Marty I removed the right carb and drip pan. The O-ring was somewhat swollen in diameter. I used a bit of Easy-Turn fuel lube to stick it back into the slot. I will order a couple of spares for future. The upper right mounting bolt took about 30° rotation before the torque wrench clicked at 26 ft-lb. I replace the upper right lock washer using the carbon steel Nord-loc and no Lock-Tite. I torqued all three bolts to 30 ft-lb, dry, per the latest Notice. I ran out of time today and will need another day to do the shroud mod and the upper left bolt.
I am committed now to trying the Nord-Loc washers without Lock-Tite. I really want to be able to put the torque wrench on them when I inspect them. Because the Nord-Locs are unproven by field experience on the engine bolts, I plan to check them at 15 hours. Then 25 then perhaps longer. If the bolts loosen, I will probably remove the Nord-Locs and use Lock-Tite blue 243, like the majority of others. Right now I feel pretty confident the Nord-Locs will work and they are a more elegant solution than glue :rolleyes:.
I did an engine start today to check for leaks because I had done an oil change. The motor was noticeably smoother at idle with all the bolts back in. I had noticed some increased vibration when the motor was cold, and I thought it was due to colder weather. It was due to the loose bolts and so I wanted to mention the obvious; any increase in vibration would be reason to pull the cowls and check things over.

Tony

DonFromTX 12-04-2010 07:54 PM

Someone mentioned earlier that perhaps the bolts coming loose are NOT the problem, only the symptom of another deeper problem with the design of the engine mount itself. It seems to me that if it is flexing enough to loosen bolts, then perhaps it needs a brace somewhere to stiffen it up. If so, that would also shine some light on the slow response so far for a fix. I would submit that even after the bolts are secured, it may be a good thing to keep a close look at the motor mount itself, looking for signs of distress cracking etc...

rschy 12-04-2010 08:00 PM

Nord-locs are for application without heat cycles. Why wouldn't you loctite when a 100% of the people using it including myself haven't had any problems?
IMHO not using a ball driver like Van's suggest is a lack of common since. The problem is the powder coat anyway. Get rid of it and you can just use the split ring lock washers.

Mich48041 12-04-2010 08:06 PM

Nord-Lock washers
 
Quote:

Nord-locs are for application without heat cycles.
rschy,
Where did you read that? I am interested in reading the full report and reason behind that.
Thanks,
Joe

todehnal 12-05-2010 05:16 AM

Quote:

Originally Posted by Tony_T (Post 490818)
I am committed now to trying the Nord-Loc washers without Lock-Tite. I really want to be able to put the torque wrench on them when I inspect them. Because the Nord-Locs are unproven by field experience on the engine bolts, I plan to check them at 15 hours. Then 25 then perhaps longer. If the bolts loosen, I will probably remove the Nord-Locs and use Lock-Tite blue 243, like the majority of others. Right now I feel pretty confident the Nord-Locs will work and they are a more elegant solution than glue :rolleyes:.
Tony

Hey Tony,
I also am using Nord-Locs without the glue, only I am not flying yet. Please keep us informed as you accumulate hours. Not having loctite in there, you will be able to check the actual torque values for change! I sure like that idea.
Tom

Mark Henderson 12-05-2010 08:40 AM

Removing the powder coating from the mating surfaces per Vans new instructions is no problem for those who haven't hung their engine. For the 65 + who are flying, it's another issue. Anybody tried this yet?

JBPILOT 12-05-2010 09:00 AM

Mark - good point but -
 
For those of us that have had loose bolts ( most of us ), the surfaces in question have had time to work off tiny imperfections, and compress the paint to the point it is not that big an issue. If you add plenty of Loctite, and retorque them, I think they will stay put just fine. If in doubt, take one out at the next annual, and clean it and put it back in. If you keep an eye on the torque seal, and if it has stayed put, you have little to worry about. With 'blue' Loctite, you could re-do them every annual if it makes you more comfortable. Check the torque before you remove them just to see if you can detect any changes. I think everyone will find that 'blue' will satisfy this BIG problem. Lets report anything we find as we go along. If something better comes along, fine, but Loctite should give you comfort for now.

John Bender

Mich48041 12-05-2010 09:26 AM

Which came first?
 
The old saying, "Which came first, the chicken or the egg?" applies to the powder coat. Did the powder coat wear away first and thus loosened the bolts? Or did the bolts loosen first and then the moving parts wore away the powder coat? I suspect the latter. Some builders have NOT removed the powder coat and have used Loctite on the engine mounting bolts and have flown many hours without the bolts coming loose.
I agree with John Bender. Loctite will prevent the bolts from turning. It will be interesting to hear from those who are using Nord-Lock washers after a long test period. Van's service bulletin to remove powder coat and tighten to 30 foot pounds should extend the time before the bolts come out. :D
Joe

Peterk 12-05-2010 10:42 AM

Nordlocks
 
As Joe said earlier, the true testing is done in the field, not on a calculator. Like Tony and some others I too am going to use the Nordlocks without the Loctite simply because I think we need to be trying different methods and reporting back for future builders. I have nothing against Loctite, just think we need more than two people taking another path. My plane has 185 hours on it so much should be settled in. We'll see how it goes. Like Tony, I have read nothing in the tons of Nordlock info that relates to heat. Would like to see that. And of course, Rotax (and thereby Vans) will not endorse Loctite (or Nordlocks) and I can understand why. Loctite cannot be retorqued without removal and cleaning. Nordlocks have never been tried period on this engine. Thus goes the experimental aircraft business. As long as we all keep each other up to date on regular check-ups, things should be fine. My only remaining concern is for the poor slobs who build away in their garage and don't have a computer and put their bolts in with those stupid split washers. We all know where that ends up.

MartySantic 12-05-2010 11:03 AM

Quote:

Originally Posted by Peterk (Post 490951)
My only remaining concern is for the poor slobs who build away in their garage and don't have a computer and put their bolts in with those stupid split washers. We all know where that ends up.

Which brings up a question. Does Van's Aircraft consider their notification a MANDATORY change? I would certainly think that would be the case with respect to this flight critical item.

We were told MANY times during the early build process, with the multitude of REVISED plan pages that VAN'S would SPECIFICALLY state to the builder via a notification if a change was considered to be MANDATORY and REWORK is required.
This did occur with a few previous items.

I received two e-mails from Van's. The first was the FF-1207 top cooling shroud modification. The second indicating the capscrew torque should be increased to 30 ft-lbs per the ROTAX documentation, and the powder coating should be removed on the engine mount mating surface. Nowhere a hint that the retorque would most likely cure the problem and the retorque, torque seal and periodic inspection should be sufficient. (My interpretation.)

Nowhere a hint that this change was mandatory. Did I miss an e-mail?

HAS THEIR NOTIFICATION POLICY CHANGED??


All times are GMT -6. The time now is 03:02 AM.