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If you have a Rotax for example which uses springs to hold the bits together until the rust takes over, try applying a line of heat resistant silicone along the spring. This will absorb some of the vibration in the spring and extend its service life.


Also handy if you are flying a pusher and the spring breaks. Springs should be lock wired also to prevent them falling off. Particularly useful for pushers.


It is an old trick, but some may not know it.





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Hi Chris


Information like this is probably fairly basic and obviousfor you with your training. But itcan be vitally important to us amateurswho are building and maintaining our RAA aircraftin many cases with no training in this field.


I for one would like to see a lot more of this basic information or tricks of the trade if you like. Maybe a basic printed text of fundamental principles of maintenance etc or regular articles on the forum. Personally, I think printed texts are more useful as they can be carried around and lkely to be perusedmore easily than starting up the computer to look for some particular item. But both could be complimentary.


This is obviously getting more complicated with the advent of a whole new range of composite materials used in construction and about which nobody seems willing to put pen to paper. Even the Jabiru construction manual that I have is very short on detail about the curing of fibreglass epoxy materials. The information on it isalmost an exact copy of the manufacturerstest figures that are publishedon the internet. I for one did not build a fibreglass canoe while I was at school fifty years ago. See the emphasis on metal work in articles in the "Kitplanes" magazine on rivetting on metal aeroplanes. I think this is great material and would be extreemly useful to anyone buiding a aerooplane.


But there is still a need for the basic information like the note that you have put in about looking after theRotax springs. Jabiru 2200shave a few springs on them as well to "secure" the exhaust system and air ducting.


I am also aware that silicone should be kept away from epoxy based composite materials.


I am reminded of an occasion when an ultralight pilot builder was looking at another non RAA builders aircraft and noted that the lock wiring on the propellor hub bolts was wired up so that the tighter the wiring was it would tend to undo the nuts.


The way the lock wiringwas done,the nuts could undo a full turn before the lock wiringcould have any effect if anyof restrainingthem from coming looser.


The lock wire should have been set up so that it would get tighter if there was any tendency for the nuts to come loose!


Regards Ross



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Guest micgrace



Rotax has this informationin their engine maintenence manual. It's available online. Also installation manuals and overhaul/parts manual.


Micgrace :)



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Information like this is probably fairly basic and obviousfor you with your training.

Hi Ross,


By no means should you be putting me on a pedastal as the wealth of all knowledge as there are infinitely more members / pilots out there with more technical knowledge than myself.


I will admit that I did not know of this trick either before last year, but it was told to me by Lee Ungermann whilst on our inspections of school aircraft.


I will endeavour to post more little 'tidbits' of info which get picked up from time to time as it may just be useful for someone and the net is a great place to store copious amounts of useless and sometimes useful information ;)


The best form of information gathering is to talk to other pilots and go to fly-ins. (then post the knowledge here)







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along with the run of Stag along the spring it is also a good idea to add a little spark plug anti sieze to the contact area of the spring and the retainer. this will help to stop the dry rub and eventual wearing thru of the two. when you lockwire the spring run the wire thru the center of the spring. this will keep the spring in situ and then run another piece of lock wire around both sides of the spring and this will retain the pipe. (redundency). I am surprised that this is not written into the maintanence manual, as this has been a problem since the dawn of rotax. the correct spring, stretchedlength and tension is a must as well.


when you replace a spring.(before it breaks) check the condition of the contact area for rough wear that will shorten the life of the new spring.



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  • 2 months later...

Another suggestion is use a HPC coating on the entire exhaust system incliding the springs, then fill the springs with silicone after running a lockwire through them. I think the coating is well worth the money, not one speck of rust in 6yrs. Mind you it hasn't rained here for about that time and the only time its seen the coast is when it left Lismore when new.



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