Oil leaks, fittings and hoses

A couple more things on oil hoses and fittings:

Rotax provides the 912 with either AN-08 or Metric style oil fittings on the engine, oil cooler and oil tank. You can identify these by looking at them.  The metric fittings have a convex cone on the hose fitting that fits into a concave socket on the engine side.  The AN-08 fittings are the opposite, they have a concave socket on the hose end fitting that fits over a convex engine side fitting.  The metric fittings work best with the 12mm hose, and the AN-08 fitting use the 12.5mm hose.  The industry considers 1/2" and 12.5mm hose as the same.

I have seen where some folks have used 12.5 mm (1/2") hose on the metric fittings and then just clamped them down a bit more. Its an easy mistake, but they will likely end up leaking a some point. The 12mm hose fits the metric fittings perfectly. 

Hi Guys ,

First post since becoming a Rotax 912 ULS owner and joining the forum.

A question for Roger Lee …

I see in many posts that you recommend Oetiker clamps for fuel lines but fuel injection clamps for oil lines ?

I thought Oetiker clamps were great for both applications . Can you explain your preference ?

Also wondering about Oetiker clamps for other connections , such as large coolant hoses and couplers on the way to and from the rad .

My new plane needs all hoses replaced and it’s infested with worm clamps !

Thanks

Hi Marc,

You certainly could use Oetiker's on other hoses. If you do use them make sure you get the right size and don't over clamp the hose and crush it to death. The fuel injection clamps are easier to remove vs an Oetiker, but they both work. Oetiker's come in tons of sizes. You just have to make sure you use the right one for that application.

Fuel injection clamps offer a good 360 degree seal and easy to remove if need be.

I worm drive type clamp is okay on some hoses just use something better than the old serrated notched worm drive clamps like you use on a garden hose. These can over cam and strip and become lose and the serrated openings can cut into the hose. The worm drive type clamps I use and many others are Wurth Zebra clamps. No serrated openings, less likely to cut into a hose and unless you get carried away in tightening them they don't over clamp and strip out and loosen. That said if you get carried away you can damage any clamp.

Too many people try to over clamp a hose. If it's over a barbed fitting it will damage the inside part of the hose.

I prefer Oetiker's on fuel hoses and Band-It clamps on the fire sleeve. These are an industry standard. 

p.s.

Too many using Band-It clamps apply way too much pressure. These could crush your finger if someone were to clamp it down and apply a little force. Knowing how to use a tool or an accessory is very important knowing it's limitations

Hi Roger ,

Thanks for the informative reply . The 15 yr old airplane I purchased has old school worm clamps on every connection and has never had a rubber change . I'm just in the process of getting all the supplies together and am trying to use best (better!) practices . I've been looking at various Rotax installations and have been surprised that worm clamps seem to be the norm !

I'll use a combination of Oetiker , FI clamps and , if needed , better quality lined screw clamps . I would love to buy the Wurth Zebra clamps but I can't find a source that doesn't require a minimum of 10 or 25 pieces . Do you know of one ? One reasonable choice appears to be Breeze lined clamps available at Aircraft Spruce .

Is it important to have a constant tension clamps on the  25mm coolant lines ? Mine has worm clamps but looking for best practices .

Thanks,

Marc

"am trying to use best (better!) practices . I've been looking at various Rotax installations and have been surprised that worm clamps seem to be the norm !"

Absolutely I'm on your side. "Best or better practices".

The old serrated worm drive clamps to me are old school and an old tradition. Time to move into the 21st century. You see lots of older A/P's using these.  There are better ways now days.

Knock on wood I've never had a leak or a damaged hose from using my clamps and I do lots of hose changes every year. I've done 4 in the last 5 weeks.