Electric fuel pump

by in 912 / 914 Technical Questions 12 years ago

I would like to hear about the pilots experience regarding the subject of using the electric fuel (Rotax engine type 912- uls2) pump during the whole flight, and if the use caused damage.
The reason for my qestion is that I got different opinions about the subject of using the electric fuel pump, some say it is dameging while others say it is a life saver and it doesnt causes any damege

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Re: Electric fuel pump

by Roger Lee » 12 years ago

Roger Lee

126 5.13k 4.55k

Hi Ruv K,

Why do you think Rotax would install a mechanical pump that would not work for a high wing or a low wing? Some Mfg's and personal aircraft owners are a little paranoid that the engine will just quit. Yes having a backup electric pump for a low wing is good advice. Some of this training about using the secondary pump and when to use it comes from old school teachings. Just like when a mechanic changes the oil in the Rotax like he does the Lycoming. Old school thinking and no new school education. Knowing your specific engine characteristics and when to use certain devices or techniques should be learned for each specific engine and Continental and Lycoming 50 year old info needs to be reconsidered when you own a Rotax. A Rotax is a different animal than the other common engines.
Thinking of it as a motorcycle engine is closer than comparing to a Lycoming or Continental. A lot of this comes from the past and darn few of these people have ever done any real testing.
I personally happen to have a high wing and wanted to know the real story. (I do not have a header tank.) I pulled the pump completely and just joined the two hoses together. The plane would fly at full rpm without a pump at all. I put the pump back in line and removed it from the gearbox and let the fuel flow through a dead pump. I could fly at 5000 rpm before the engine wanted to sputter. At 4800 rpm I could have flown and even taken off with 4800 rpm. Now a low wing may not flow as well through a dead pump, but just turning on an electric pump just to do it??? If the mechanical pump is working then it will most likely work to touchdown. The mechanical pumps do not just stop working like you flipped a switch. They tend to loose pressure over time. If you have a fuel pressure gauge you can monitor it. The electric pumps tend to add .5 - 1 psi to the over all pressure. The carbs can only flow so much so why would you need the electric pump. Many of my friends with low wings never use the electric pump and only give it a quick test during the pre-flight to see if it is working then shut it off. Like many things people are slow to change especially if they are being led by old school knowledge.

How many engines other than the Rotax aircraft engine has a backup electric pump on it or even has one installed in any other engine applications where the engine has its own mechanical pump?
How many Rotax engine's mechanical fuel pumps quit like you flipped a switch?
(That is without any warning, which was usually over looked at an inspection if they even did an inspection)

Bottom line is they are dependable pumps. Have they had some go bad over the years, yes, but it isn't any different than any other mechanical part.

Most, but not all (things can fail), of the Rotax engine issues can usually be traced back to poor or no regular maint. or doing something to it that wasn't supposed to be done.

I tell all my clients, education, education, education. Forget what Joe told you from next door.

All the Rotax manuals are your Bible to do what has been proven to work since the inception of the 912 and what has not worked.

I guess I better get down off my soapbox before I fall off. Old age or something like that. :lol:

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-349-7056 Cell

Thank you said by: , YEN NIEN YU

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Re: Electric fuel pump

by Scott Geiger » 12 years ago

Scott Geiger

0 3 0

Brand new 912s engine. Engine started sputtering in a climb on takeoff. The electric fuel pump saved us.
The engine has also sputtered and begun to die on level flight.
Engine will sputter and presumably quit in a prolonged climb.
The plane is a Searey Amphibian. The tank is much lower than the engine.
One would be foolish not to have an electric pump for backup.
It sounds like mechanical fuel pump is not good.

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Re: Electric fuel pump

by Kevin Machniak » 12 years ago

Kevin Machniak

6 167 40

I have a high wing , I test the electric pump during preflight and that's it. It is there in case you need it, but not used normally. I have never required it as of yet, but its good to know its there. 286 hrs on 912 ULS.

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Re: Electric fuel pump

by bill martin » 12 years ago

bill martin

10 757 0

I have a 912uls with the tank mounted about two feet lower than the engine. I also have an electric pump as a backup but, like Kevin, I have never run it except during preflight.

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Re: Electric fuel pump

by Art Pileggi » 12 years ago

Art Pileggi

1 2 0

Brand new 912s engine. Engine started sputtering in a climb on takeoff.

My AFM (Tecnam Sierra) specifies fuel pump on for takeoff and landings. My Cirrus did as well. I don't really remember but I am pretty sure my CTSW and C172R did as well.

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