flat6
Well-Known Member
An oil condition sensor is badly needed for any kind of reliability.
Engine Oil Monitoring Device
- Thread starter flat6
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Seems like thread drift to me, but I gotta ask: What would this sensor observe, report, etc? And how does this relate to a seal coming out and dumping engine oil?
The ones in modern auto engines are an algorithm in the ECU that sums up time at temperature, cold starts, and time at rpm, then turns on a light. Not much help here...
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flat6
Well-Known Member
An oil condition sensor is an online monitor. It tracks metal debris trends and can signal a warning just before a catastrophic failure in the engine. Either before tackoff or during flight. In latter case The pilot can then turn down power and look for a place to land. Engine conversions with no benefit of long term tests in an engine dyno will need this. Specially highly tuned ones.
You’re describing a chip detector and it doesn’t work on non-ferrous metals such as those found in bearing material.
Does the product exist? Sounds worthy of its own topic. Want me to establish a new thread and put this on it? I have info that will contribute...
Billski
We do have chip detectors in turbine engines and in some helicopter gearboxes. The ones I know about are all-or-nothing devices, with them both being known for some notable saves and for frequently crying wolf over an otherwise clean system because a single machining chip that stayed in the box bridged the detector...
As somebody who has worked with debris specifications for products, the target levels are usually set in terms of particle material, size, and count or weight per part washed or unit volume of liquid based upon known sensitivity of the product to particle material, size, and count or weight. You pass the carrier liquid through a filter of a specified size and use a microscope with automated machine vision to categorize the particles and give the results. I know we are not going to do this with a gadget in the engine.
Let's remember that piston engines MUST tolerate some quantities of:
To be useful, such sensors will have low rates of both false positives and false negatives. They probably should also have a means of watching viscosity vs temperature, acid and water content of the oil in order to warn that an oil change is needed, as acid buildup in oil and viscosity change are two big reasons we change oil on piston engines.
Billski
As somebody who has worked with debris specifications for products, the target levels are usually set in terms of particle material, size, and count or weight per part washed or unit volume of liquid based upon known sensitivity of the product to particle material, size, and count or weight. You pass the carrier liquid through a filter of a specified size and use a microscope with automated machine vision to categorize the particles and give the results. I know we are not going to do this with a gadget in the engine.
Let's remember that piston engines MUST tolerate some quantities of:
- Hard ferrous debris off of drive mechanisms during initial run;
- Other hard debris from piston ring and cylinder walls during initial run and break-in;
- Ongoing very finely divided wear debris from ongoing operation;
- Manufacturing and build debris in the form of abrasive particles, machining chips and packing materials;
- And dust/fibers from bodies and clothing of workers;
- The list goes on and on.
To be useful, such sensors will have low rates of both false positives and false negatives. They probably should also have a means of watching viscosity vs temperature, acid and water content of the oil in order to warn that an oil change is needed, as acid buildup in oil and viscosity change are two big reasons we change oil on piston engines.
Billski
Since we have methods of measuring these in real time is there really enough variation in service life of the oil under different operating patterns to warrant this kind of monitoring?
Simply changing the oil every XX hours/miles seems to have proven to be reliable and economical..........with regard to oil service life.
Dan Thomas
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This is a solution in search of a problem.
Oil-related engine failures are almost always a result of running out of oil. The pilot didn't check for adequate oil before takeoff, maybe. Or an ancient oil hose failed and dumped all the oil overboard. An oil monitoring device isn't going to prevent stuff like that. We already have oil pressure and temperature gauges that mostly get ignored until the engine starts making funny noises.
Then there are the pilots that start the engine in very cold weather without any preheat and with high-viscosity oil in the engine. The pump can't suck hard enough on that thickened oil to get it into the pump and push it to the rest of the engine, so bearing damage happens before the oil gets there, and eventually the engine falls apart. An oil monitoring device might warn of that damage, but the scenario could be prevented altogether by better training and proper care of the engine. Unfortunately, there are too many pilots that just don't care about learning anything more, and usually it's something other than oil system failure that gets them. Poor aviation decision-making, it's called. Flying into bad weather. Running out of fuel. Doing stupid stuff at low altitude and stalling and spinning in. Low flying that is ended by some powerlines or a cell tower. Buzzing someone and pulling up hard and getting the accelerated stall and spin.
Too many folks want technology to do all their thinking for them. It's one of the reasons why airplanes are getting too expensive to buy and maintain. Fancy systems cost money to install and fix. Oil pressure and temperature tell us a lot if we know even a little bit about engines. Checking the filter during an oil change tells us a bunch more. Neither of those is expensive and they're not failure prone and don't add needless weight and complexity.
One of the biggest causes of engine corrosion is short flights in cold weather, or ground-running the engine and putting the airplane away. Those actions put combustion gas condensates in the crankcase that eat the engine from the inside out. The engine doesn't get warm enough to drive out the moisture. There is no PCV system in an aircraft engine, and it wouldn't work if there was one. Too little manifold vacuum at the typical power settings. Again, an oil monitoring system isn't going to prevent mistakes like that. It might tell you that there's a lot of iron and aluminum in your oil, but that's about it. Only education can fix such problems.
Oil-related engine failures are almost always a result of running out of oil. The pilot didn't check for adequate oil before takeoff, maybe. Or an ancient oil hose failed and dumped all the oil overboard. An oil monitoring device isn't going to prevent stuff like that. We already have oil pressure and temperature gauges that mostly get ignored until the engine starts making funny noises.
Then there are the pilots that start the engine in very cold weather without any preheat and with high-viscosity oil in the engine. The pump can't suck hard enough on that thickened oil to get it into the pump and push it to the rest of the engine, so bearing damage happens before the oil gets there, and eventually the engine falls apart. An oil monitoring device might warn of that damage, but the scenario could be prevented altogether by better training and proper care of the engine. Unfortunately, there are too many pilots that just don't care about learning anything more, and usually it's something other than oil system failure that gets them. Poor aviation decision-making, it's called. Flying into bad weather. Running out of fuel. Doing stupid stuff at low altitude and stalling and spinning in. Low flying that is ended by some powerlines or a cell tower. Buzzing someone and pulling up hard and getting the accelerated stall and spin.
Too many folks want technology to do all their thinking for them. It's one of the reasons why airplanes are getting too expensive to buy and maintain. Fancy systems cost money to install and fix. Oil pressure and temperature tell us a lot if we know even a little bit about engines. Checking the filter during an oil change tells us a bunch more. Neither of those is expensive and they're not failure prone and don't add needless weight and complexity.
One of the biggest causes of engine corrosion is short flights in cold weather, or ground-running the engine and putting the airplane away. Those actions put combustion gas condensates in the crankcase that eat the engine from the inside out. The engine doesn't get warm enough to drive out the moisture. There is no PCV system in an aircraft engine, and it wouldn't work if there was one. Too little manifold vacuum at the typical power settings. Again, an oil monitoring system isn't going to prevent mistakes like that. It might tell you that there's a lot of iron and aluminum in your oil, but that's about it. Only education can fix such problems.
Dan has put this one thorough the stadium lights!
My motto is, "if you want your engine to be more in tune, you should be more in tune with your engine." If it's your airplane you should know where the pressures & temps should be at cold start, full power climb, cruise and especially your hot idle oil pressure.
Consistent readings tell a lot about the health of the engine. Cutting open the oil filter and keeping track of what is found is important. I also use a magnetic drain plug and check it for and metal grit. Then there is the oil analysis that should be done. Listening to the engine will tell you a great deal. Make sure in flight to get the oil hot enough for long enough to allow it to purge the water out. For what it's worth I do not use an air oil separator, although I bought one for the plane. Mine uses no oil and the very small amount of color I get on the belly is easy enough to wipe off every now and again.
TFF
Well-Known Member
Modern auto engines are trying to counter environmental laws and keep oil in use as long as possible and still make it to warranty. It also fools the owner that extended oil changes saves money. I run synthetic in my truck and is eligible to run extended oil changes. I don’t ; dump the junk out. Airplane oil in an aircooled engine is flat cooked at oil change time. When someone says their engine is using oil, my first question is when is the oil change due? Usually they are trying to get five more hours. They will put more oil in than trying to change it just to get to that oil change number.
flat6
Well-Known Member
On-line and In-line Wear Debris Detectors: What's Out There?
Wear debris analysis is essential to effectively gauging machinery life. When machine components begin to wear, the evidence can usually be found in the lubricant flowing through the machine. For...
www.machinerylubrication.com
ferrous and nonferrous particles can be detected by induction techniques and polar contaminants like water and glycol can be detected by capacitance measurement.
The cheapest sensor out there is the one fitted on current bmw engines which uses capacitance measurement. Available from eBay. I prefer to use both myself but the inductance based sensors are expensive. And not available on eBay at all. I have installed the bmw sensors in my car in the engine and driveline.
Please cite products that are real time, suitably accurate, reasonably priced, and long lived in the engine sump for acid and viscosity so that we could use them.
Will they really offer any improvement over a conservative oil change interval? Probably not...
I agree, but a monitor would need recognize a bunch of oil failure modes, including viscosity shifts, acid increase, solids accumulation recognizing abrasive quality and particle siz. Tall order when just changing the oil at regular hour intervals works so well.
Billski
Dan Thomas
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Yes, it might be nice to have such a device, but it wouldn't be cheap and it wouldn't weigh nothing and it wouldn't stop the degradation of the oil itself and it sure wouldn't compensate for a pilot's carelessness. It would, 99.99% of the time, tell us, at around 40 or 50 or 60 hours, that the oil needs changing.
One has to stop and count up all the stuff he wants in his airplane. The cost, weight, maintenance of it all, and so on. It's way too easy to keep adding stuff until the airplane is useless. Small homebuilts are especially vulnerable to any weight increases. And whatever money spent on gimmicks is money not available later on in the building process, possibly halting the whole project.
I've said it many times: If you want to improve safety, spend the money on more training and education. It's amazing how much stuff the average PPL simply doesn't get in groundschool, or it's so academic that it just goes over his head. The stupid, entirely preventable accidents prove it. What you don't know really can kill you. Too many students want to learn just enough to get past the written and flight tests, and no more. And they forget a bunch of that soon after they're licensed.
Training and education also don't add more weight and complexity.
I know of none that currently meet all those parameters. Real time and suitable suitably accurate? They do exist. I've used them in the oil field. Inexpensive they weren't and I can't say they would survive at the temperatures needed........ but I suspect they could be adapted.
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Think we have the same overall thought? It may be possible, but I doubt there is any real world benefit. Regular oil changes work for most of us. Oil sampling for those with expensive or critical equipment takes care of the rest.
Show us the need. Please cite engine failures in flight that can be attributed to oil problems. We have plenty of maintanance cases of rusting cylinder walls and camshafts, swallowed valves, separated heads and thrown cylinders., but I just do not recall engines failing in flight from anything resembling used up oil...
Dan Thomas
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Right. They usually just wear out sooner. Compressions and oil pressure start to fall off, oil consumption goes up, sparkplugs get fouled quickly. The typical stuff that's supposed to be caught at annual inspections.
