Engine burping
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Engine burping
During preflight of an aircraft using the Rotax912UL engine, it requires the engine to be burped. Why is it?
1. It's only to return the oil back to the oil tank so that proper oil level can be checked?
2. Or is it also to circulate the and remove air from the oil system to facilitate easier starting?
Also does burping apply to all dry sump piston engines or just this particular Rotax model?
Cheers!
1. It's only to return the oil back to the oil tank so that proper oil level can be checked?
2. Or is it also to circulate the and remove air from the oil system to facilitate easier starting?
Also does burping apply to all dry sump piston engines or just this particular Rotax model?
Cheers!
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It's called "gurgling": the process is to return oil back to the tank so you can check the oil level. See towards the end of this document:
http://www.lightaircraftassociation....ril%202011.pdf
ifitaint...
http://www.lightaircraftassociation....ril%202011.pdf
ifitaint...
And if the oil reservoir is well below the engine, as it is on my Apollo Fox, you will not get it to burp no matter how much you turn the prop - the oil will already have trickled down by the extremely reliable force of gravity.
Still I do hand turn the prop before starting, two or three revolutions, to activate ("wake up") both the oil circuit and the fuel circuit.
Still I do hand turn the prop before starting, two or three revolutions, to activate ("wake up") both the oil circuit and the fuel circuit.
If there's a grinding problem in the mags it could start.
You want to ressaure yourself? Try handpropping your Rotax - you'll have a hard time, and small chance of success. Especially if it is cold.
Last, but not least: gurgling is indeed standard practice for 912'ers, can be found in all engine/airframe handbooks. Whoever told you not to do it (by which I mean: specifically on a Rotax 4-stroker) is, err, less than sufficiently familiar with this type of engine (to put it as politely as I could).
Last edited by Jan Olieslagers; 15th Oct 2014 at 14:11. Reason: be as clear as possible
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Just to add that in some installations some of the oil can drain into the crankcase from the tank. In those cases, gurgling becomes very important to avoid potential damage.
Dry sumped engines of all varieties will have differing procedures depending on the relative locations of tank, cooler and crankcase. The majority of these engines have much higher capacity scavenge sumps than supply, to try and avoid oil build-up in the engine.
Dry sumped engines of all varieties will have differing procedures depending on the relative locations of tank, cooler and crankcase. The majority of these engines have much higher capacity scavenge sumps than supply, to try and avoid oil build-up in the engine.
) I learrned from it!
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I've been taught to never hand turn the prop. If there's a grinding problem in the mags it could start.
...and which will be a thousand times worse when starting the engine with the electric starter - because the engine speed will be much higher. Turning the prop by hand is a way of distributing a tiny bit of oil around the engine at a very gentle speed.
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Hi Shumway76,
Not sure which aircraft you fly, Technam P2002? If so, I recently had a lesson with an instructor and am part way through conversion onto the Technam. I was surprised about the gurgling aspect too! I find it hard to pick up on the 'gurgling' sound.
I was also surprised at what a nose low attitude the aircraft has inflight compared to the PA-28 / C-152. I kept having to remind myself to push the stick forward to lower the nose
Not sure which aircraft you fly, Technam P2002? If so, I recently had a lesson with an instructor and am part way through conversion onto the Technam. I was surprised about the gurgling aspect too! I find it hard to pick up on the 'gurgling' sound.
I was also surprised at what a nose low attitude the aircraft has inflight compared to the PA-28 / C-152. I kept having to remind myself to push the stick forward to lower the nose
Dear Kandi,
If you find it hard to discern the gurgling sound you have never properly heard it - but, as I already said, on some types it simply doesn't occur. You do have to remove the oil filler cap, though, and better remove the dipstick too. One problem is to find a convenient place for both, where they won't fall off at the merest movement, yet be sufficiently conspicuous that you don't forget to put them back in place before starting.
As for pushing the nose down, isn't your issue with using a stick for the first time, having only used yokes before? You'll soon get used to it. But really, if that must be discussed further, it would be better done in a separate thread - this one is about gurgling a Rotax 4-stroker.
PS and forget about Technam, these fine but slightly overweight craft are called Tecnam.
If you find it hard to discern the gurgling sound you have never properly heard it - but, as I already said, on some types it simply doesn't occur. You do have to remove the oil filler cap, though, and better remove the dipstick too. One problem is to find a convenient place for both, where they won't fall off at the merest movement, yet be sufficiently conspicuous that you don't forget to put them back in place before starting.
As for pushing the nose down, isn't your issue with using a stick for the first time, having only used yokes before? You'll soon get used to it. But really, if that must be discussed further, it would be better done in a separate thread - this one is about gurgling a Rotax 4-stroker.
PS and forget about Technam, these fine but slightly overweight craft are called Tecnam.
Last edited by Jan Olieslagers; 15th Oct 2014 at 20:28.
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Just so as there is no doubt - the Rotax is very different to other aircraft engines, so those going on about not gurgling as it's potentially harmful to yourself or the engine are unfortunately incorrect.
That said, the 91x will start by hand (search this forum and others for links to AAIB reports), so treat the propeller with due respect.
Finally, the gurgling process works much more efficiently when the engine is at operating temperature. We gurgle after flight then if the oil is on the dipstick flat on the pre-flight then you're good to go.
That said, the 91x will start by hand (search this forum and others for links to AAIB reports), so treat the propeller with due respect.
Finally, the gurgling process works much more efficiently when the engine is at operating temperature. We gurgle after flight then if the oil is on the dipstick flat on the pre-flight then you're good to go.
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Just so as there is no doubt - the Rotax is very different to other aircraft engines, so those going on about not gurgling as it's potentially harmful to yourself or the engine are unfortunately incorrect.
So in that respect rotating the prop of a Rotax is about as safe as rotating the prop of a Lycosaurus - it should not be a problem since there should not be a spark (Rotax) or fuel (Lycosaurus) if the engine was properly shutdown. But you treat the prop with respect anyway.
Thank you, BackPacker, you neatly confirmed what I already stated in #06
If you could stop the engine after your last flight by short-circuiting both circuits (and Rod1 is right, there are no magnetos properly speaking) then the grounding circuit is all right.
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No mice in mainland Europe??? Never assume anything when dealing with loud whirly things (and yes I own a 912 powered aircraft and know how hard (nearly impossible but not quite) to hand prop they are, but that's no reason to assume your wiring is intact)
There is also the option of cranking the engine on the starter, ignition off, if that configuration is available. Yes, I know this means you have to get in and out of the aircraft, but your choice. The engine will still gurgle with the filler cap on, but you won't hear it over the noise of the starter motor. Personally, I just pull the prop through, without offering my head up as a sacrifice. It's a Pioneer, so the height is a bit low for comfort.
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Dear Jan Olieslagers, thank you for pointing out my incorrect spelling of the Tecnam, I am of course aware of the correct spelling ... Tecnam and not Technam. I was just following your advice about throwing in a few spelling mistakes here and there ... 
Re: Flying the Tecnam ... as you said, maybe it's the fact that i'm not used to flying with a stick (as opposed to a yoke) that I need to get used to ... I hadn't considered that
Re: Flying the Tecnam ... as you said, maybe it's the fact that i'm not used to flying with a stick (as opposed to a yoke) that I need to get used to ... I hadn't considered that
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Rod1 - Why is overfilling a Rotax 912/4 so bad? It has a separate oil tank with an over flow . The oil pump sucks the oil from this tank into the engine, and the blow by crankcase pressure pumps it back. Any excess is discharged into the airstream.
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Environmental concerns? Cost of oil? Having to wash the fuselage more often because of the oil streaks?
In addition to those, keeping track of oil consumption is one of the things you do to keep track of the overall engine health. After a break-in period the oil consumption of an engine should stabilize at some low number. If that number starts to rise all of a sudden it's time for some TLC.
If you regularly overfill the engine you can't keep track of what was consumed and what was blown overboard.
In addition to those, keeping track of oil consumption is one of the things you do to keep track of the overall engine health. After a break-in period the oil consumption of an engine should stabilize at some low number. If that number starts to rise all of a sudden it's time for some TLC.
If you regularly overfill the engine you can't keep track of what was consumed and what was blown overboard.