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
Joe,
You have it nailed. Number 2 is easier than number 1. I, for one and others I know of are testing the Nordlock theory. Others, Loctite. I expected us to be the beta testers because as you say, "we are the field" and that is the way experimental aircraft are made safer. Your number 1 is very puzzling because it could save lives. We can only contact those we know of. Others have much larger resources to get the message out. And when you realize that many of them are readers and contributors to this forum its stunning. The EAA alone participates in this forum and yet ignores this issue. Are they all waiting for Van's to bless their comments? This is experimental, grass roots aviation, not corporate politics. Of course if you think about it, safety issues only become issues following fatalities. Shouldn't be much of a wait. Thanks for your personal concerns.