Rotax 912 ULS oil and cool/winter flying

[AviatorCrafty]

Since I probably won't be flying until June, I figured I'd get this off my chest since I've noticed some interesting quirks of the 912 ULS since transitioning to Tecnam aircraft from a 0-200D Cessna 162. My transition began around the winter times so temps were cold, I noticed on some preflights when trying to burp the engine to check the oil I'd turn and turn the prop maybe even up to 20 times (tiring) and only get oil up to the bottom of the grommet where minimum oil is displayed, and even then after engine start, I'd let it sit for a bit to warm up and the oil temperature would never rise, even after taxiing to the runway and doing a run-up, it wouldn't budge. I asked two separate CFIs about it and I was told it was a "Rotax thing" where you wouldn't see any oil temp rise. On one flight I was flying a P92 with the G3X and the oil temp was in the caution range the whole flight which seemed really weird to me. Is the Rotax just different from other engines like that in the winter? Forgive me since I only have about 6 hours in Tecnam aircraft.

[ShawnM]

Are you seeing any movement on the instrument? If not I would say to check the sending unit for the oil temp and work your way back from there. The oil temp will rise just fine on a Rotax with a normal OAT. Obviously faster in warmer temps and slower in cooler temps but nonetheless it will rise to see the temps on the instrument. How cold was it? Why would you ask a CFI and not a LSRM? It's not a "rotax thing" to not see any oil temp rise. Ask your mechanic for help not your CFI.

[drseti]

Because the Rotax is triple-cooled (cylinder fins to cool the jugs, water to cool the heads, and an oil radiator to cool the innards) it is one of the coolest running engines out there. This is a very good thing on the summer, but in cooler seasons, causes just the issue you mentioned.

The best practice would be to preheat the engine before every flight. You can find an article on how to kludge together an effective and inexpensive preheater here:
https://avsport.org/publicat/nonfict/preheat.pdf

There is an inexpensive thermostat for the liquid cooling system, standard on some installations and optional with others, sold by Leading Edge Airfoils. Easy to install (easiest if you do so the same time as a Rotax 5-year rubber replacement). On an SLSA it will require an LoA from the manufacturer.

Many of us use a winterization kit in the winter - consisting merely of an appropriate length of aluminum HVAC duct tape placed across the front of the coolant radiator. That mod requires no LoA. Just remember to remove it when ambient temperatures start to rise in the summer.

[AviatorCrafty]

Because the Rotax is triple-cooled (cylinder fins to cool the jugs, water to cool the heads, and an oil radiator to cool the innards) it is one of the coolest running engines out there. This is a very good thing on the summer, but in cooler seasons, causes just the issue you mentioned.

The best practice would be to preheat the engine before every flight. You can find an article on how to kludge together an effective and inexpensive preheater here:
https://avsport.org/publicat/nonfict/preheat.pdf

There is an inexpensive thermostat for the liquid cooling system, standard on some installations and optional with others, sold by Leading Edge Airfoils. Easy to install (easiest if you do so the same time as a Rotax 5-year rubber replacement). On an SLSA it will require an LoA from the manufacturer.

Many of us use a winterization kit in the winter - consisting merely of an appropriate length of aluminum HVAC duct tape placed across the front of the coolant radiator. That mod requires no LoA. Just remember to remove it when ambient temperatures start to rise in the summer.

Great ideas! But sadly I rent the planes I fly

[drseti]

Great ideas! But sadly I rent the planes I fly

That would not preclude you preheating the engine before flight, as the preheater described in my article is completely portable, can be used on any plane, and requires no aircraft modifications.

[MrMorden]

A strip of aluminized tape across the oil cooler does wonders for keeping the 912 from running too cold in the winter. You might have to experiment a bit to get a feel for the right size for conditions. Just watch oil temps carefully after putting it on. That's the 20 cent solution. Here in Georgia "winterizing" my CTSW consists of adding tape. Done.

[3Dreaming]

Since I probably won't be flying until June, I figured I'd get this off my chest since I've noticed some interesting quirks of the 912 ULS since transitioning to Tecnam aircraft from a 0-200D Cessna 162. My transition began around the winter times so temps were cold, I noticed on some preflights when trying to burp the engine to check the oil I'd turn and turn the prop maybe even up to 20 times (tiring) and only get oil up to the bottom of the grommet where minimum oil is displayed, and even then after engine start, I'd let it sit for a bit to warm up and the oil temperature would never rise, even after taxiing to the runway and doing a run-up, it wouldn't budge. I asked two separate CFIs about it and I was told it was a "Rotax thing" where you wouldn't see any oil temp rise. On one flight I was flying a P92 with the G3X and the oil temp was in the caution range the whole flight which seemed really weird to me. Is the Rotax just different from other engines like that in the winter? Forgive me since I only have about 6 hours in Tecnam aircraft.

Minimum oil should be displayed on the flat of the dipstick, unless they are doing something different with the P-92. A little tape on the oil cooler and some on the radiator should help with getting it up to normal operating temps.

And yes they can take longer to burp when they are cold.