oil system

by Ευάγγελος in 912 / 914 Technical Questions 5 years ago

The aircraft landed and I had 2.6 liters of oil. When I checked it the next morning,before the flight, I had 2.4 liters of oil . That is, when I check the amount of engine oil in the morning it looks less than what I count after the last flight of the previous day. What is the actual quantity and when should I refill it. I know the limits for the 912S2 engine are 2.5-3 liters

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Re: oil system

by Roger Lee » 5 years ago

Roger Lee

127 5.21k 4.79k

When you change the oil you use all 3 liters of Aero Shell Sport Plus 4 because it comes in liters. I always love it when I see that someone puts in the logbook they used 3 qts. of Aero Shell Sport Plus 4. :)
If you use a motorcycle oil that is measured in quarts remember that 3 qts. is 8 oz. less than 3 liters. 3 liters during an oil change with a new filter should put you right at the top of the dip stick. Also remember to hand prop the engine before the oil is changed to get whatever extra is down in the bottom of the crankcase. If you forget this step then you can easily over fill the system and when you add your 3 liters it will over flow out the oil tank vent tube.
DO NOT rotate the prop when there is no oil in the tank or when the filter is off or you will inject air into the system.

p.s.
You can pre-fill the oil filter before installation which is a good idea.

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-349-7056 Cell

Thank you said by: Ken Ryan, Ευάγγελος

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Re: oil system

by Bill Hertzel » 5 years ago

Bill Hertzel

13 1.95k 7.97k

If the Oil was Hot when you measured it after the flight and Cold the next day, that could account for a lot of the difference

2.400 Liters of Motor Oil at 0°C will expand to 2.568 Liters at 100°C. (7% per 100°C)
You may not have been that Hot, or that Cold, but if your measurements were off a little like 2.58 and 2.43, That would be a 6% change only requiring an 85°C(150°F) temperature change.

Bill Hertzel
Rotax 912is
North Ridgeville, OH, USA
Clicking the "Thank You" is Always Appreciated by Everyone.

Thank you said by: Ευάγγελος

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Re: oil system

by Roger Lee » 5 years ago

Roger Lee

127 5.21k 4.79k

Hi Bill,

Where did you get those numbers? I was a HazMat Tech in my former life and hadn't ever seen this expansion rate of motor oil in my chemistry.
The amount you have listed in change is 5.4 ounces. That's would be a huge amount for the amount in the tank for oil to expand.
I went and plugged in some numbers and found the difference was only .17 ounces for motor oil from 0 C to 100 C. The expansion coefficient is .00070 for motor oil. It isn't 7% it is .0007%.

p.s.
You made me hurt my brain on this one. LOL :)
I haven't done chemistry for over 12 years.

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-349-7056 Cell

Thank you said by: Guilherme Tomazini, KHAN

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Re: oil system

by Roger Lee » 5 years ago

Roger Lee

127 5.21k 4.79k

Thermal Expansion Equations Calculator
Science Physics Formulas
Solving for change in volume
change in volume
Inputs:
volumetric expansion coefficent (b)
.00070

initial volume (Vinitial)
2.4

final temperature (Tfinal)
100

initial temperature (Tinitial)
0

Conversions:
volumetric expansion coefficent (b)= .00070kelvin^-1 = 0.0007kelvin^-1
initial volume (Vinitial)= 2.4liter = 0.0024meter^3
final temperature (Tfinal)= 100celsius = 373.15kelvin
initial temperature (Tinitial)= 0celsius = 273.15kelvin
Solution:
volume change (Vfinal - Vinitial)= 0.000168meter^3
Other Units:
= 0.000168meter^3
= 0.0010265231587291barrel UK
= 0.0014529462827424barrel US dry
= 0.0014316420939078barrel US federal
= 0.0014089176148927barrel US liquid
= 0.0010566882094326barrel US oil petroleum
= 0.0046193523090644bushel UK
= 0.0047674354194117bushel US dry
= 168centimeter^3
= 4.6350499404118E-5cord firewood
= 0.00037080399523294cord foot wood
= 0.73909504850311cup Canada
= 0.672cup metric
= 0.71009447223661cup US
= 1.68deciliter
= 0.168decimeter^3
= 0.0059328640092101foot^3
= 0.0369548174564gallon UK
= 0.044380904796169gallon US liquid
= 10.251989007915inch^3
= 1.68E-13kilometer^3
= 0.168liter
= 168milliliter
= 168000millimeter^3
= 5.9127709595043ounce UK fluid
= 5.6807558139096ounce US fluid
= 0.29563879977686pint UK
= 0.35504723836935pint US
= 0.14781966001478quart UK
= 0.17752361918468quart US
= 0.000168stere
= 9.4605248338777tablespoon UK
= 11.361511627781tablespoon US
= 28.381254856911teaspoon UK
= 34.084534883458teaspoon US
= 0.00021973570404482yard^3

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-349-7056 Cell

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Re: oil system

by Bill Hertzel » 5 years ago

Bill Hertzel

13 1.95k 7.97k

As included in your own calculation...

[quote]
initial volume (Vinitial)= 2.4liter = 0.0024meter^3
volume change (Vfinal - Vinitial)= 0.000168meter^3
Other Units:
= 5.6807558139096ounce US fluid[/quote]
Even larger than my 5.4oz estimation, but close enough. :)

0.0024 + 0.000168 = 0.002568meter^3 = 2.568liter = ≈2.6liter, the observed quantity more or less.

The Coefficient of Expansion (CoE) for Oil is listed as 0.0007 per unit (Degree C), Not PerCent.
0.0007 per degree = 0.07% per degree... Times 100 degrees = 7% per 100 degrees C.

The major Viscosity controlling component of motor oil is Paraffin Oil (Wax). CoE = 0.000764
A little more than Motor Oil.
Paraffin Wax is the operating agent used in radiator thermostats because of its large amount of expansion with temperature.

Measure your Oil levels on a cold engine.
The 2.5 to 3 liter fill Spec allows for a lot of additional Fudge Factor.
There is enough headspace designed into the oil tank to accommodate the expanding hot Oil.

P.S.
I think this was in my High School Physic class and that was 50 years ago. ;)
P.P.S.
In reference to the "Fudge Factor".
I could not find the CoE of either Fudge or Chocolate.
I found Butter to be 0.00066
So I guess Fudge will be in the 0.0006 to 0.0007 range. :woohoo:

Bill Hertzel
Rotax 912is
North Ridgeville, OH, USA
Clicking the "Thank You" is Always Appreciated by Everyone.

Thank you said by: Guilherme Tomazini

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