It could be just as reliable as the lovely fuel qty float or capacitance gauges we've had on all of our trainers.

Raise your hand if you've ever had a fuel qty gauge suddenly show an abnormal reading in flight. Did you land?

Now imagine it's an oil quantity gauge. That's a lot of unnecessary precautionary landings.

On the fuel gauge, it depends. If it suddenly goes to zero, I'm not worried. If I see it start to steadily decrease and I don't have another tank, I'd seriously consider landing. I don't remember ever seeing that failure mode in flight.

Subaru vehicles monitor oil quantity and will turn on an idiot light in the instrument panel when the quantity is running low (don't ask for an exact oil level as this varies from car to car). Clearly this technology is "do-able" at relatively low cost and relatively high reliability.

Hopefully no one would base any action on an oil quantity gauge only without confirmation of oil temperature and pressure. That's probably why we don't have oil quantity gauges in addition to temperature and pressure in light planes.

Hopefully no one would base any action on an oil quantity gauge only without confirmation of oil temperature and pressure. That's probably why we don't oil quantity gauges in addition to temperature and pressure in light planes.

Use your dipstick Jimmy !

The time I didn't get the dipstick inserted right on a T210, the windshield acted as a pretty good warning means. It indicated an excessively high amount of oil on it.

DH Beaver has a dipstick right in the cockpit by the co-pilot's left knee. Can even add oil in flight.

Is there a reason why these aren't being added to our planes? I found the subject mentioned in a couple threads but no mention of these inexpensive sensors.

https://www.aircraftspruce.com/catalog/ ... sensor.php

https://aircraftextras.com/oilquantitysensor.htm

A few months ago a local pilot traveled commercial to Colorado to do an inspection on his beloved TN/TC V-Tail that he sold several years ago. He regretted selling the plane and was excited to get it back.

During the pre-inspection he noticed a light sheen of oil on the tail surfaces. Checking the oil level he found that a large amount of oil had been lost in the short flight to the inspection airport. It was determined that the turbocharger had failed resulting in a dramatic loss of oil.

It doesn't take much imagination to think what would have happened had the turbocharger failed sooner or later than it did.

Both my partner and I had the oil filter adapter gasket fail on our Debonair which resulted in almost all the engine oil dumping on the ground at the fuel pump. Had the failure for either of us happened a few minutes sooner we would certainly have had a forced landing.

At a recent lunch get together the first pilot I mentioned asked why don't we have oil level sensors in our planes when it is routine for many automobiles to have them. It didn't take long before one in the group found out that they are available and at reasonable price compared to other safety items we've invested in.

Cool!
Long ago I had a [similar] ad-hoc system installed in a Cessna 182 for a long ferry flight. No dipstick, but a garden pump-pressure sprayer installed on the copilot side, with a tube going through the firewall to the oil filler neck. I pumped one quart of oil every five hours.

Nobody? Maybe pictures will help....
https://www.aircraftspruce.com/catalog/ ... sensor.php

https://aircraftextras.com/oilquantitysensor.htm

Are they legal to use on certified aircraft? I'm not seeing any clear language about that.

FWIW, everything in certified aviation costs a fortune. FAA is impossible. Volumes are small. Stakes are high.

As a point of reference, PT6 dipsticks that only read when engine is off are at least $12k each. And in the past, there have been issues with them that caused A/Ds requiring they be replaced.

In an airplane, your oil temperature gauge is a proxy for an oil level gauge. if the oil is leaving so quickly that it doesn't show as elevated temperature, then you will know soon enough that you are out of oil as the engine seizes.

Working in engineering for an engine manufacturer, I have fought against this idea my whole career. Every time they have been tried they result in countless warranty claims for false-low indications, while no one can ever point to an example that they actually helped. The lone exception being on some engines where we use them to take a reading before engine cranking after a suitable length of shutdown time. Even then it takes a couple of events for the computer to start to show a message, because of the issues of being parked on a slope, etc before engine start.

I've had a couple of BMWs with electronic oil quantity indicators. They have been very reliable and I have never had any issues. When BMW first introduced these sensors, there was lots of push back from owners. Everyone wanted a dipstick.

I have had a couple of instances with significant oil leaks that are not visible from the cockpit. And oil sensor would have been most welcomed. Oil pressure and temperature indications will be a day late to be useful.

There's lots of gauges/sensors GA doesn't seem to embrace besides oil level sensors. Maybe the loss of oil failure mode is so small that the false positives equal the number of actual warnings? Heck low end Cessnas and Pipers don't really have good charging system monitors:

-- chip detectors
-- fire detectors
-- vibration analyzers (like GEM, but more refined)

--paul