I have the weirdest issue with my oil pressure, this is with a factory pipistrel virus SW, rotax 912iS engine with MTV-33 hydraulic constant speed prop.
Could be that the flux capacitor near the aft nacelles is running short on dilithium, check Jefferies tube 37. This can happen after encountering a spatial anomaly during a static warp maneuver. Conduct a Baryon sweep while in the presence of an Omega particle without violating the prime directive... ATC is really anal about that one, something about intergalactic annihilation. Theyre on a power trip if you ask me though... Anyway, these issues are common in the Alpha Quadrant and really cant be fixed without a collective hive-mind. Fortunately the Borg are always nearby and are really good at fixing crap. Thier service leaves much to be desired but the work they do is top notch. They tend to charge a lot though so use them only if you literally have no other option.
Can you explain how the pitch governor could cause this type of problem? No mechanic has so far said this is potentially the issue but that doesn't mean you are incorrect. I've confirmed from MT prop and a rotax technician that the hydraulic prop is a dead end, it doesn't take any oil pressure away from the main system, it'll use oil so it's possible the oil pump is not big enough to handle the load of the engine and hydraulic prop. Since this issue has been since new, as well as another guy here also has same issue my gut feeling is that it's how the engine is setup. Stay tuned I'll have a video out in a week or so with another modification i'm going to try.
Darryl, Hi - I just thought that since your problem changes with power, (manifold pressure?), and with throttle settings, I wondered whether your propellor pitch changes like is the case in some planes where the throttle and pitch controls are linked. Changes in pitch will obviously activate or inactivate oil pressure through the governor and I just thought that there might be a possibility of that being the cause. It just seems logical to me to consider this as a possible cause. The fact that it’s been since the beginning makes me think this even more. It therefore doesn’t sound like anything is ‘wrong’. One way to find out is to speak to people with the Pipistrel Virus LSA in the US, where the propellor pitch is fixed. If they don’t have the issue, I would pursue it as a likely culprit....
Magnus Murphy interesting appreciate the input. So are you thinking there may be something wrong with our prop governors or perhaps the issue is having a hydraulic prop on this engine? If so then the only fix I see is to put a non hydraulic prop on.... but I am super confused because this engine was designed to install a hydraulic prop. You’d think rotax or MT would test this before selling it to customers.... there is one similar pipistrel in Quebec with same engine and prop with decent oil pressure 40psi at higher altitude. But it seems like anyone without a hydraulic prop has about 55 psi at any altitude. I realize it’s working harder at higher altitudes which may explain why I lose pressure the higher I climb, I’m just dumbfounded that no one before me has seen this issue and that pipistrel sells the aircrafts like this. Before I changed my oil lines my pressure was in the teens at 15,000 at least now with these new lines I get about 25psi. I’m hopeful my next mod will increase this another 10psi.
Hi Darryll.... Please understand I’m not an expert - in fact, I know almost less than nothing. I’m just throwing an idea out there since all I know is that pitch governors uses engine oil to do their work and the association with throttle and altitude made me think of the possibility. It would be extremely interesting to find out what the Pipistrel engineers say about the situation. It is highly interesting that you confirm the fixed pitch US LSA models might not have the problem. This, as they say - ‘thickens the plot’! Magnus
Magnus Murphy yes I fully understand but I also want your opinions as well. I’ve talked to pipistrel directly after sending them months of emails with no response on the issue. All they could come up with is an oil pump issue or pressure relief valve. Both of which the other guy here tried replacing on his engine with no improvement. I’m thinking more and more that this is a setup issue, maybe the oil pump is not big enough for this type of setup. I just can’t believe that these companies have not tested this before selling it to a customer so it’s hard for me as well to think that this could be it. There is no larger oil pump available for this engine. My next course of action is to reduce the amount of resistance in the oil system, ie oil lines
Perhaps you are 'running out' of oil at altitude due to the volume demand of the governor at altitude. As the pitch gets coarser, the governor holds more oil. Also, the engine might be holding more oil at rpm as well since the oil is bouncing around through all the passageways. It appears that the rotax is a dry sump, so perhaps the remote oil sump doesn't have enough volume to fill the running engine and the coarse propeller governor. I think you can run the engine on the ground with the oil tank cap off and monitor the levels, then you could manually adjust the propeller to full coarse and see what happens to the oil level. Possible fixes, if this is the issue, is overfilling the oil tank or using a larger oil tank.
To be scientific about this, let's consider the effects of temperature and pressure on the oil system -- we know these change with altitude. Also, you noted that the CS draws more pressure as it works harder at altitude. There we have three variables to apply to a schematic of the oil system. WAG: Is there an apportioning valve in the CS? Good luck!
John Fife yeah it all adds up. The problem is that oil pressure should not be affected by altitude change, or very slightly. I’m leaning towards a possible flaw in the design, just not big enough oil pump to power hydraulic prop. Will be doing a modification to try and help lessen the demand on the pump
With the prop setting at a normal cruise speed, If you climb to, say 10000 feet or so, go to nearly slow flight, note the oil pressure, then dive within the yellow arc speed, does the oil pressure trend down as the prop is being forced to go coarse to hold the speed down. If it does, that seem to point at prop pitch being the contributing factor. Do you know if the woodcomp prop configuration you had in the other Pipistrel behaved this way?
I have not played with airspeed to this extent to see what it does, but it would seem that I have better pressure the slower I fly, and worse when faster as I have better oil pressure with low power settings and maintaining altitude. I've installed some new equipment to try and improve oil pressure will have a video up shortly. MT prop is also sending me a part to try, they also seem to think it could be partially due to prop pitch.
air pressure drops with altitude. problem is noted after many hours on this engine on your and at least one other pipistrel. amateur guess: something that oil flows thru has weakened over time and allowing passage area to increase/flow pressure to decrease beacuse of bernoulli law. you changed some hoses...are those the only hoses oil circ path? not engineer or aviation related professional...retired architect who has enjoyed your channel and solves world problems in morning bike rides. hasn't worked yet. free advice worth every penny you pay. good luck.
Hey I’ll take any advice from people on this issue even talking about it helps to understand it more. This issue has been since the engine is new, but it has never been an issue until now because I’m flying a lot of high altitude work. I replaced every oil line on the engine, although this helped improve the pressure it did not fix the issue. I don’t fully know how/where the oil all goes but it also passes through the radiator, oil pump and crank case as well as prop governor but that is a dead end line just to pressurize the prop. My though at this point is that the hydraulic prop is demanding more pressure from the oil pump even though it’s closed system and the pump is not strong enough to keep up the pressure. The higher I climb the harder the prop has to work to maintain rpms which would demand more oil pressure.
Still no fix, I have been able to improve oil pressure by reducing oil lines with new thermostat that bolts to the radiator by Franz, but now I have high oil temps. Franz has sent me replacement thermostat with same issue so either its bad design or I got two lemons
Could be that the flux capacitor near the aft nacelles is running short on dilithium, check Jefferies tube 37. This can happen after encountering a spatial anomaly during a static warp maneuver. Conduct a Baryon sweep while in the presence of an Omega particle without violating the prime directive... ATC is really anal about that one, something about intergalactic annihilation. Theyre on a power trip if you ask me though... Anyway, these issues are common in the Alpha Quadrant and really cant be fixed without a collective hive-mind. Fortunately the Borg are always nearby and are really good at fixing crap. Thier service leaves much to be desired but the work they do is top notch. They tend to charge a lot though so use them only if you literally have no other option.
Chris Capps
You are misinformed. The Borg will not service light sport aircraft.
haha. very helpful.
Have you considered a pitch governor problem? Might make sense since your constant pitch prop uses oil pressure.....??
Can you explain how the pitch governor could cause this type of problem? No mechanic has so far said this is potentially the issue but that doesn't mean you are incorrect. I've confirmed from MT prop and a rotax technician that the hydraulic prop is a dead end, it doesn't take any oil pressure away from the main system, it'll use oil so it's possible the oil pump is not big enough to handle the load of the engine and hydraulic prop. Since this issue has been since new, as well as another guy here also has same issue my gut feeling is that it's how the engine is setup. Stay tuned I'll have a video out in a week or so with another modification i'm going to try.
Darryl, Hi - I just thought that since your problem changes with power, (manifold pressure?), and with throttle settings, I wondered whether your propellor pitch changes like is the case in some planes where the throttle and pitch controls are linked. Changes in pitch will obviously activate or inactivate oil pressure through the governor and I just thought that there might be a possibility of that being the cause. It just seems logical to me to consider this as a possible cause. The fact that it’s been since the beginning makes me think this even more. It therefore doesn’t sound like anything is ‘wrong’. One way to find out is to speak to people with the Pipistrel Virus LSA in the US, where the propellor pitch is fixed. If they don’t have the issue, I would pursue it as a likely culprit....
Magnus Murphy interesting appreciate the input. So are you thinking there may be something wrong with our prop governors or perhaps the issue is having a hydraulic prop on this engine? If so then the only fix I see is to put a non hydraulic prop on.... but I am super confused because this engine was designed to install a hydraulic prop. You’d think rotax or MT would test this before selling it to customers.... there is one similar pipistrel in Quebec with same engine and prop with decent oil pressure 40psi at higher altitude. But it seems like anyone without a hydraulic prop has about 55 psi at any altitude. I realize it’s working harder at higher altitudes which may explain why I lose pressure the higher I climb, I’m just dumbfounded that no one before me has seen this issue and that pipistrel sells the aircrafts like this. Before I changed my oil lines my pressure was in the teens at 15,000 at least now with these new lines I get about 25psi. I’m hopeful my next mod will increase this another 10psi.
Hi Darryll.... Please understand I’m not an expert - in fact, I know almost less than nothing. I’m just throwing an idea out there since all I know is that pitch governors uses engine oil to do their work and the association with throttle and altitude made me think of the possibility. It would be extremely interesting to find out what the Pipistrel engineers say about the situation. It is highly interesting that you confirm the fixed pitch US LSA models might not have the problem. This, as they say - ‘thickens the plot’!
Magnus
Magnus Murphy yes I fully understand but I also want your opinions as well. I’ve talked to pipistrel directly after sending them months of emails with no response on the issue. All they could come up with is an oil pump issue or pressure relief valve. Both of which the other guy here tried replacing on his engine with no improvement. I’m thinking more and more that this is a setup issue, maybe the oil pump is not big enough for this type of setup. I just can’t believe that these companies have not tested this before selling it to a customer so it’s hard for me as well to think that this could be it. There is no larger oil pump available for this engine. My next course of action is to reduce the amount of resistance in the oil system, ie oil lines
Change the oil pressure unit and relocate from engine to fire wall
Perhaps you are 'running out' of oil at altitude due to the volume demand of the governor at altitude. As the pitch gets coarser, the governor holds more oil. Also, the engine might be holding more oil at rpm as well since the oil is bouncing around through all the passageways. It appears that the rotax is a dry sump, so perhaps the remote oil sump doesn't have enough volume to fill the running engine and the coarse propeller governor. I think you can run the engine on the ground with the oil tank cap off and monitor the levels, then you could manually adjust the propeller to full coarse and see what happens to the oil level. Possible fixes, if this is the issue, is overfilling the oil tank or using a larger oil tank.
Trevor Chernoff good thoughts but I tried overfilling the oil tank and it did nothing
To be scientific about this, let's consider the effects of temperature and pressure on the oil system -- we know these change with altitude. Also, you noted that the CS draws more pressure as it works harder at altitude. There we have three variables to apply to a schematic of the oil system.
WAG: Is there an apportioning valve in the CS?
Good luck!
John Fife yeah it all adds up. The problem is that oil pressure should not be affected by altitude change, or very slightly. I’m leaning towards a possible flaw in the design, just not big enough oil pump to power hydraulic prop. Will be doing a modification to try and help lessen the demand on the pump
With the prop setting at a normal cruise speed, If you climb to, say 10000 feet or so, go to nearly slow flight, note the oil pressure, then dive within the yellow arc speed, does the oil pressure trend down as the prop is being forced to go coarse to hold the speed down. If it does, that seem to point at prop pitch being the contributing factor. Do you know if the woodcomp prop configuration you had in the other Pipistrel behaved this way?
I have not played with airspeed to this extent to see what it does, but it would seem that I have better pressure the slower I fly, and worse when faster as I have better oil pressure with low power settings and maintaining altitude. I've installed some new equipment to try and improve oil pressure will have a video up shortly. MT prop is also sending me a part to try, they also seem to think it could be partially due to prop pitch.
air pressure drops with altitude. problem is noted after many hours on this engine on your and at least one other pipistrel. amateur guess: something that oil flows thru has weakened over time and allowing passage area to increase/flow pressure to decrease beacuse of bernoulli law. you changed some hoses...are those the only hoses oil circ path?
not engineer or aviation related professional...retired architect who has enjoyed your channel and solves world problems in morning bike rides. hasn't worked yet. free advice worth every penny you pay. good luck.
Hey I’ll take any advice from people on this issue even talking about it helps to understand it more. This issue has been since the engine is new, but it has never been an issue until now because I’m flying a lot of high altitude work. I replaced every oil line on the engine, although this helped improve the pressure it did not fix the issue. I don’t fully know how/where the oil all goes but it also passes through the radiator, oil pump and crank case as well as prop governor but that is a dead end line just to pressurize the prop. My though at this point is that the hydraulic prop is demanding more pressure from the oil pump even though it’s closed system and the pump is not strong enough to keep up the pressure. The higher I climb the harder the prop has to work to maintain rpms which would demand more oil pressure.
Hi - what was the fix for this problem ?
Still no fix, I have been able to improve oil pressure by reducing oil lines with new thermostat that bolts to the radiator by Franz, but now I have high oil temps. Franz has sent me replacement thermostat with same issue so either its bad design or I got two lemons