I am now at my wits end. Rotax deliver their engines in the USA fitted with AN oil and fuel connections and that is what my FWF kit comes with.

For the rest of the world Rotax deliver the engine with "metric" connections for the fuel pump, fuel rail and oil tank - which is what was delivered to me here in Australia.

Only problem is that no one seems to be able to tell me exactly what standard of "metric" Rotax uses. there is bound to be a European (or DIN) spec for what Rotax uses but I can't find any reference to it and the local hydraulic shops just stare blankly. Yes, they have a few fittings that screw on, but the bores are way too narrow and clearly not designed for one another.

Internet catalogues are no use without knowing the right specification.

This is starting to look like a nightmare. Adapters to AN may help in one or Two spots, but I am not a fan of adding an inch or so to overhangs at a pressurised joint.

The final solution may have to be to order spare parts, including a new fuel rail and fuel pump assembly if I can't identify a source of proven, specified metric fittings.

Yes, the local agent is aware of the problem, but so far no solution.

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Comment by Geoff Klestadt on April 9, 2014 at 3:52pm

Hi Michael, the threads on the fuel pump are 14 x 1.5 with a concave seat in the top (opposite of AN fittings). The engine fuel rail fittings are the same. The oil lines are 18 X 1.5.

I've found Stauff and many others.

I can get  aluminium billet adapters to AN for everything but the clearances on the fuel pump mounting look a little tight according to what I can see in the images on the Skytek website.

For those Two fittings I looked for replacement 90 degree replacements for the AN fittings.

However, once I did that I discovered that there are at least Eleven families of connection styles with an infinite number of variants for differene those tails, O rings etc. As anyone who has done stuff with cars, hydraulics., etc. just because Two connectors screw together doesn't mean they will seal properly and a leaking or broken fuel or oil line can be a death sentence in an aircraft.

Hence my question which has yet to be answered: exactly what DIN or ISO standard does Rotax employ for its metric fittings and where can I find some?

If I can't find metric fittings that will exactly fit the Rotax Metric fittings (I've been trying for Two days now) then I think I'm going to order Rotax AN replacement parts for the oil lines and fuel return line. I may have to use adapters elsewhere. If that isn't going to work its a new fuel pump and  Fuel rail assembly.

Comment by Michael Sipman on April 9, 2014 at 7:49am

do you have the diameter and thread pitches?

Stauff make a range of metric adaptors

there is also a company here in western Australia called Alpha engineering that manufacture odd adapters etc.

good luck


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