Fuel pump noise

Michael Rubio, have you had any solution to this yet?

I have a similar plane and have the same noise problem. The factory replaced the pumps with the new pumps already before delivery of the plane and they say to original pumps was not that loud.

I have covered the pump housing with noise dampening "memory foam" and relocated some cables and connectors that touched the housing but the improvement is small. I notice the noise level varies over time between very loud and extremely loud.

I found the pumps make almost as much noise even if I hold them in my hands so it is probably not resonances in the hull that cause the noise.


Can it be that the pumps cavitate due to restrictions in the fuel supply?
Restrictions like the quick-connection of fuel hoses at the wings, the fuel selector valve or fuel-pick-up in the tanks.

I am considering to do an experiment with fuel supply directly from a fuel can with only a 8 mm hose between. To see if the noise disappears.

Have you tried this?

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Hi Mikael,

I have not been able to solve the issue and I have also not tried to change to an 8mm hose... 

In the meanwhile I have been informed that: "As by actual official information from Rotax, the reason of noise is, that the toothed mechanism inside the new fuel pumps is too tight. Rotax is now searching for a solution and considering exchange of all fuel pumps. "

I just found this post and I have the fuel pump noise described here. Mine started at 15 hours so I sent them in for the recall rotax has thinking I had a problem and didn't want to wait any longer.

I received the new pumps and they make the same noise. Both sets only make a noise when both pumps are on. No noise on one pump only. Pressures never change up or down just the noise you can hear even with noise cancelling headsets.

Any new ideas?

Edit, this is on a 915is if it makes any difference. Thanks

Your noise is because of cavitation on the pumps inlet side. You need to reduce the restriction in the incoming fuel lines.
Especially any "minor" restrictions like couplings with internal small area or to small diameter fuel lines.

Even if thicker fuel lines themselves maybe are not need it makes it easier to get couplings/fuel-valves with enough internal diameter.

Quick connections with internal fuel stop often has much restriction/small internal area.