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Artur Munteanu

Oil Qty

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I wonder if is normal to have this difference of oil qty between the two engines.

 

Why would it not be? In all the manner of random things in the world, would you really think it's possible that those two engines see the same exact amount of air, same exact amount of time (think back to your start flows - are you starting them at the same time? which one do you usually start first?), the exact same temperatures, the exact same throttle settings, and the exact same shutoff times?

 

I know aviation seems rigid and very precise, but there's a decent amount of variance.

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(think back to your start flows - are you starting them at the same time? which one do you usually start first

I start first the engine nr.2 then engine nr.1 Ok is normal, but I thought that in the cruise the qty oil should become stable at same parameters.

 

Make sure it doesn't go below 76 percent ;)

So the less quantity is 76%. If goes below then is a failure of the engine?

 

If I look better at the scheme, I see that is also a difference between the two system of quantity hydraulic usage:

 

hydsch345.gif

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I start first the engine nr.2 then engine nr.1 Ok is normal, but I thought that in the cruise the qty oil should become stable at same parameters.

 

Oil, like fuel, is something that burns off over time (or, for certain older planes, some just gets heaved overboard because that's how the plane is feeling that day). If #2 is consistently started before #1, then #2 would logically have less oil over time than #1. Each engine has its own oil reservoir and it does not crossfeed.

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Hi,

and don't forget that "Indicated oil quantity may decrease significantly during engine start, takeoff and climb out. If this occurs, engine operation is not impacted and the correct oil quantity should be indicated during level flight". (B737 FCOM Vol.2 page 340)

 

Ciao

 

Andrea

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Oil, like fuel, is something that burns off over time (or, for certain older planes, some just gets heaved overboard because that's how the plane is feeling that day). If #2 is consistently started before #1, then #2 would logically have less oil over time than #1. Each engine has its own oil reservoir and it does not crossfeed.

Got it.

 

Artur your scheme indicate the hydraulic usage, not engine oil or not?

Yes it's hydraulic. Is better seen here how works:

schemehyd.gif

 

Anyway even if the two system are independent, with hydraulic you can steel move fluid from one system to enother (it's not the indicated procedure, to avoid cross contamination you should top up that system with fresh fluid). But I thought that with oil engine you could use a transfer procedure as well.

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What a complicated diagram! I prefer the Boeing generated ones... Less crap on it.

 

Oil quantity will also differ due to the dihedral of the wing.

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Hi Artur

 

The Engine Oil quantity indication has nothing to do with the hydraulic system!!?? each engine has his own oil reservoir and are not connected to each other, so if the engine oil level is different between both engine's that is completely normal just make sure that each engine oil level is above 60 % (12 U.S. quarts) before you start the engine's, to make sure that there is enough oil just fill the engine oil before each flight. 

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