Rotax Rubber hose replacement and why it's needed

We are due to replace our hoses in May this year-do we have to use Rotax hoses or can we fit other types?

My .02 cents:

This can be a debatable question up to a point. It partly depends on your aircraft's certification, operating limitations, factory POH and country you live in.

But the short answer is this and it may even depend on which engine you have i.e. 912iS or 912 UL or ULS.

Most of us in the US use standard fuel hose rated for ethanol which most fuel hoses are these days. It could be 3/8", 5/16" or 1/4" depending on where it's used in the engine. Then there is the 25mm or 1" coolant hose. Many use what they can buy at local auto stores. Hose Mfg's like Gates or Dayco. I prefer Gates Barricade fuel hose and Gates Green Stripe 1" coolant hose. I buy these in bulk since a do quite a few hose changes and never had an issue in over 15 years. If you have a 912iS engine then the fuel hose must be rated for fuel injection because of its higher pressure. If you have a 912UL or ULS then regular carburetion hose or Vapor recovery hose as some call it works just fine. It's rated pressure is 50 psi which is more than enough for our fuel pressures down around 3.5 psi to 6 psi. I have found many using fuel injection hose trying to force it over barbed fittings and fuel injection has has very little give so it strips the inner liner of the hose which then floats downstream and also weakens the hose at the fitting. Carburetion hose or vapor recovery hose has some give and that usually doesn't happen. I blow out every hose before putting it in place and sometimes apply a little universal lube on the fitting to make sure the hose slides smoothly without any damage over the fitting.  Guess what universal lube is? LOL There is NO US equivalent to the Rotax 17mm coolant hose on top of the engine and underneath the cylinders. Use Rotax 17mm hose. Any US hose is either too small or too large and people who do this are failing to do the right smart thing. When working with the 17mm spring clamps take care not to abuse them or they could become too lose. Do not pry the hose off the black coolant expansion tank as the metal is very thin and you may damage the tank and have to replace it. Then you have other Rotax parts like rubber carb sockets and "O" ring, carb diaphragms, the 66mm hose on the carb balance tube. The number one thing many don't do, but should is the rubber engine mounts on all engines. They dry and get hard and some even go the opposite way and get too soft depending on what they have been exposed to.

https://www.rotax-owner.com/en/rotax-blog/item/20-the-task-at-hand-rotax-5-year-rubber-replacement

https://www.rotax-owner.com/en/rotax-blog/item/21-rotax-5-year-rubber-replacement-the-installation-considerations

Roger,

many thanks for all that excellent advice and information, fully intend to replace all with new hoses. Safe flying!