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-   -   RV-12: Engine Mounting Cap Screws Inspection (https://vansairforce.net/community/showthread.php?t=65020)

JBPILOT 12-02-2010 01:56 PM

THE FACTS ARE - -
 
The bolts come loose - PERIOD ! Does it make a difference when - really ! They come loose. Loose bolts will create lots of problems in the threads.

Put on plenty of Loctite 'blue', and paint mark them, then LOOK at them as often as you feel comfortable. If you have good threads, put on plenty of Loctite, and *THEN* you have a problem - that is when we need to hear from you ! I think we have the solution. I have about 100 hours on mine since I put Loctite on them. HAVE NOT MOVED ! That is good enough for me. DO NOT BREAK THEM LOOSE to check them. If they have not moved, they are tight enough. If you feel the need to take one out, clean the threads and do it all over again, but just LOOK at them, don't try to tighten them or you will break loose the Loctite and then it will not be as affective.

John Bender

DonFromTX 12-02-2010 01:58 PM

I think you are correct, we are looking for a complicated solution to a simple problem.

rgmwa 12-02-2010 02:53 PM

Quote:

Originally Posted by Geico266 (Post 490000)
Rotax makes airplane engines, not airplanes. Their engines are installed into airframes. The Rotax Installation manual, Page 35 states the bolts used to secure the engine to the airframe are the responsibility of the airframe manufacturer, that would be Vans Aircraft. Other airframe manufacturers have issued SB's to cover these exact same bolts dating back to 1999. The real question is; Why can't Vans Aircraft step up to the plate and warn their customers of what is clearly an airworthiness issue. Clearly, IMHO this is their responsibility.

Larry, I agree entirely that VAN's should have been much more pro-active in dealing with this critical safety issue, and I can only assume it's a case of "responsibility shared, responsibility halved". I'm just trying to understand how they may be thinking based on their actions so far.

clucier 12-02-2010 05:01 PM

Quote:

Originally Posted by vernhendershott (Post 490057)
Hi Chris,

The bolt that they could not have checked was fine, for what that is worth, we can all have bad days, perhaps this was one of theirs. The only reason I mentioned it is if they did check the other three, then one fell out in about 10 hours, so if we are to set a reasonable interval to see that the bolts are still tight what should it be? With the data presented on this list I would expect the FAA to issue an AD Note requiring the checking of the bolts every 5 hours if they did AD Notes on experimental aircraft, we are lucky that they do not but if we follow Van's current instructions (install the bolts and split ring lock washer dry to the called out torque) then we should be checking the torque about every five hours. Forgive me if this does not sound like the kind of fun I wanted to have.

I think with blue loctite we should be good with a drop of Torque Seal and a visual inspection at 25 hours for now and if the situation remains stable then perhaps fifty hours which would match up with the oil change interval and it would not be much of an issue.

The above is only one man's thoughts, you should come to your own conclusions and do what you need to, to keep your aircraft safe to fly.

Best regards,
Vern

Thanks Vern,

I was not looking to crucify anyone but it concerns me if someone I am paying to do a thorough required inspection of a machine that could kill me if improperly maintained misses a step, i start wondering what other steps did they miss or just not complete. No one is perfect but thats why we use checklists, I would suspect they have checklists for the inspections, I know I would.

if they just chose not to do it because the shroud was difficult they should inform you of that and let you make a decision.

I truly hope it was a once in a long while event but ask yourself what if the tech "forgot" to torque your prop and it came off in flight.

I digress, and from everything I hear and see (until this) Lockwood is a first rate organization so not trying to beat them up to badly here but....

I truly hope everyone continues to share information like this good bad or in-different, it,s what makes a difference in our hobby.

rschy 12-02-2010 05:02 PM

Quote:

Originally Posted by MartySantic (Post 489902)
I reviewed the ROTAX Line Maintenance page. What are you trying to tell us?? It is merely a list of consumables??? The manual SPECIFICALLY tells us when and when not to use loctite.

In the case of the engine mount bolting, all of the USA repair centers seem to be using blue loctite for this bolting even tho the line maintenance manual does NOT suggest it.

DUH...... This tells me that Rotax is routinely using Loctite to secure BOLTS and has proof that the product works. As well as properties of the the different types of thread locking products.

BTW 120367 has 19.5 hours and the 3 bolts I check are good but I used blue Locktite on all the fasteners without self locking female ends.

Marty, I'm sorry I made such a stupid post. I thought it might be of interest to some of folks with an imagination!!!!!!!

Boomerang 12-02-2010 05:47 PM

Loose bolts on N7185A, SN#120164, with 52 hours
 
Checked the bottom two bolts right after Larry called me (Thanks Larry) and found the bottom right tight. The bottom left needed about 1/8 turn. Was not able to check the top two bolts at that time because of the inaccesability. The top right looked OK but I really did not look very close at the top left. Just assumed that it was OK. Did a closer visual check today of the top left bolt. The bolt head is just about even with the outside edge of the engine mount. How loose it is (how many turns counter clockwise) I won't know until I can get in there but as a result I am grounded until I can get my 12 to a heated work area. This will take a while. A real bummer.

dick seiders 12-02-2010 08:33 PM

Heard from Rotax Tech again today. He was not willing to commit on the blue Loctite, but I have read enough to feel firm on the 360 torque setting, blue Loctite, and torque seal with checks at each oil change. Until something better comes along, if it does that's where I am going.
Dick Seiders

Peterk 12-02-2010 09:16 PM

What is Going On?
 
Quote:

Originally Posted by dick seiders (Post 490233)
Heard from Rotax Tech again today. He was not willing to commit on the blue Loctite, but I have read enough to feel firm on the 360 torque setting, blue Loctite, and torque seal with checks at each oil change. Until something better comes along, if it does that's where I am going.
Dick Seiders

Certainly is curious. Bolts coming out right and left. Van's doesn't care, the Feds don't care (or don't read VAF...yah right). Those that Loctite swear by it, but neither the engine manufacturer nor the aircraft manufacturer...whom both recommend Loctite in much of the remaining assembly will not do so in this instance. What a bizarre situation! Of course no one did anything about the Zenith wings coming off until how many crashed? Am I missing a liablity issue here? Guess we'll find out when the first 12 smokes a hole in the dirt.

Geico266 12-03-2010 06:50 AM

Quote:

Originally Posted by Peterk (Post 490244)
Certainly is curious. Bolts coming out right and left. Van's doesn't care, the Feds don't care (or don't read VAF...yah right). Those that Loctite swear by it, but neither the engine manufacturer nor the aircraft manufacturer...whom both recommend Loctite in much of the remaining assembly will not do so in this instance. What a bizarre situation! Of course no one did anything about the Zenith wings coming off until how many crashed? Am I missing a liablity issue here? Guess we'll find out when the first 12 smokes a hole in the dirt.

Well said Pete.

The silence from Vans is deafening.

Mich48041 12-03-2010 09:43 AM

Two main issues
 
There are two main issues:

ISSUE 1. Notify RV-12 owners that the engine mount bolts are loosening and falling out.
This is a moral issue. Most of us would like to see RV-12 owners immediately notified to check the bolts. Until then, bolts are slowly vibrating out. RV-12 owners who have had engine bolts loosen can warn others by contacting aviation magazines and the EAA and the FAA. If the magazine editors received letters from several builders, they might write an article or publish the "letters to editors". The word will be spread.

ISSUE 2. Preventing the bolts from loosening.
Split ring lock washers do not work as evidenced by laboratory experiments and RV-12 field experience. It would be nice if we received official guidance on this issue. But manufacturer's do not know any more about solving this problem than the builders. Regardless of engineering theory, it is what works in the field that counts. Rotax mechanics have been using blue Loctite with success, even though they might be reluctant to officially recommend it due to liability concerns. And using blue Loctite seems to be the consensus among RV-12 builders. Nothing is perfect and Loctite has disadvantages. It has temperature limits, should not be disturbed by periodic torque checks, and makes removing bolts difficult. But it works and will keep the bolts from loosening. Another possible solution is using Nord-Lock washers. They work well holding the brake and propeller bolts. Nord-Lock washers are not affected by normal engine block temperatures; they can be periodically checked for torque; and the bolts can be easily removed with a wrench. But regardless of theory, they need to be proven in the field.

We can complain and try to influence others but we can not control what they do. What we can do is spread the word to other builders, perhaps with the help of national and international media. And we can ensure that our own engine mounting bolts do not come loose.
Joe


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