912ULS auxiliary Fuel Pump

by Blake Blomquist in 912 / 914 Technical Questions 8 years ago

I have a 912ULS w/ Bullyhawk Turbo & Wiseco Pistons.
I did not build the airplane or install the engine but it was done by a very experienced guy.
It has an auxiliary fuel switch on the panel which engages a supplemental fuel pump.
I have never seemed to need this as my fuel PSI stays at about 4.1 lbs with the primary pump.
Do most guys with the 912ULS have an "Aux. Fuel Pump"? If so... When ... Other than in the event an emergency loss of power or unexpected engine roughness would you reach for this switch or even need this at all?

Thanks all!

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Re: 912ULS auxiliary Fuel Pump

by Ken Ryan » 8 years ago

Ken Ryan

28 360 928

I believe that your engine would be similar to the Rotax 914, which means that in order for the engine to keep running, you must have an operating electric fuel pump. Standard procedure for the Rotax 914 is to engage both electrical fuel pumps for all takeoffs and landings, and to run only the primary fuel pump in cruise.

Nice airplane by the way. I am building a SuperSTOL and will be using a Rotax 914.

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Re: 912ULS auxiliary Fuel Pump

by Kevin Machniak » 8 years ago

Kevin Machniak

6 167 40

On most highwings with a 912ULS , the electric auxillary fuel pump is used when the engine mechanical pump has an issue and if the gravity flow from the wings is not enough to produce the desired power, the back up pump can also come in handy if something in the fuel system is partially blocked as well.
On my kitfox outback , I flip the fuel pump switch to test its function on the preflight check. It is there for when there is a problem and does not get used during any part of flight.

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Re: 912ULS auxiliary Fuel Pump

by David HEAL » 8 years ago

David HEAL

23 186 409

Van's RV-12 E-LSA (a low-wing airplane) with a ROTAX 912ULS has a "full-time" electric auxiliary fuel pump that operates all of the time - it has no direct control switch (however, a fuse can be pulled to deactivate it) and is "on" anytime the Master Switch is activated. Van's Aircraft's thinking (as I understand it) is that the electric pump's TBO will out-last the engine's TBO, the electric pump is on all of the time so that no pilot attention (or inattention) is needed, it is "safer" in that it is always backing up the engine-driven pump - particularly at low altitudes, it helps to avoid vapor-lock, and it is a simpler system to build and install.

As you might imagine, there is some discussion within the RV-12 builder ranks as to whether this is a good idea or not. Some builders are wiring in a direct control switch so that they can use the electric pump as they see fit - ultimately, it is up to the builder/pilot (either post E-LSA certification or EAB-LSA).

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Re: 912ULS auxiliary Fuel Pump

by Blake Blomquist » 8 years ago

Blake Blomquist

4 2 0

The 912ULS was built by Ronnie @ Mississippi Light Sport. I like the 912 because it is a "heavier duty" engine in it's own right. Ronnie puts an aftermarket turbo and Wiseco pistons in the jugs and does some strengthening of the crank. Makes close to 135 HP @ full power. Will over rev if not managed properly. Been a good motor and has been a proven performer over the past years in other airframes.

I'd check with him before making a final decision on your engine choice... Just for "good measure".... You might at the very least find something you'd like better.... Who knows! Maybe have a conversation with Billy Payne as well.... He is quite knowledgeable also.

Food for thought! Good luck with your build!

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Re: 912ULS auxiliary Fuel Pump

by Ken Ryan » 8 years ago

Ken Ryan

28 360 928

Blake, I've talked with Ronnie, with Billy and with Steve. I've gone back and forth and in the end I decided that for me the best choice is the stock 914.

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912ULS auxiliary Fuel Pump

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