My Rotax 912 ULS will soon reach 5 years with only 300 hours. Rotax recommends to replace the rubber hoses and I would like to know what other owners have done. Anyone had good or bad experiences doing it, or postponing it to 8 or 10 years?

My concerns are obviously the price of the kit and time to install, but also the risk of doing a mistake or installing a defective part. I do all the required maintenance on my plane but I am not sure that one would end up reducing the risk of failure.



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Hi Francois,
It's a pain to do. First time I did it I let it go to 6 years. When I changed the rubber hoses some of them showed signs of hardening and cracking, so I think the 5 year cycle is sensible.
Is this based on the manufacture of engine or when you first start a new engine. I know on my first engine it took a year or two until I fired it up. I've heard it takes a couple of days to do and easier to do by removing the engine. Come to think of it you might as well replace the rubber motor mounts cause they sure get shaken when that motor stops. Also I don't know how you would get those bottom coolant lines without removing the motor. How did you do it Shay, thanks.
You shouldn't have to remove the engine to change the hoses.
It probably makes sense to change the engine mount rubbers when the hoses are off though.
To do this I didn't remove the engine completely, I just undid the mounting bolts and hoisted it up a couple of inches,(I have the bed mount),don't forget to support the tail of the airplane first.
Take lots of photos before removing the old hoses.
Try to work cleanly and not get any debris into the new hoses.
Keep a record of all the items you buy to do the job for next time, it's amazing how quickly it comes around.
Every 5 years I've been replacing some rubber hose with aluminium in the fuselage, I should have used aluminium where possible when building it in the first place.
Best of luck.

I changed my carb diaphrams at ten years and had to keep them apart from the new ones ,because there was no difference, which brings up the reasons they ,degrade..heat, dry air, humidity , none of which we have to deal with ,and in the case of the fuel lines, if they are fire sleeved, rotax doesnt know what you have for coolant lines, and therefore you need to inspect, if you have the good blue silicone lines they last forever if protected,a statement of 5 years is protection for Rotax , because there are so many variables , this is not a mandatory AD..if you are changing the airframe fuel lines , get the AN -6 fittings and alum. tube from Summit Racing and do it right and be finished with that part,alum. tube is so flexable and easy to work with...     

How were your carb sockets?  Also how would you protect the blue silicone lines with firesleeve or ?

agree with Bob Jones

do what you want to but the key to changeout here at my place is whether or not the part needs changing or not....not the legal paranoia Rotax bombards us with. They're the worst about it that I have dealt with. They cry wolf so often the tendency is to ignore all the bulletins but I do skim and see if it sounds like it might be legit or just more lawyer crap.


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