What is crankcase oil return line for?

[bigJake]

As I understand it the oil in the crankcase of a 787 is gravity fed and does not circulate back to the resovoir? true? if so, then what is the return line for and if the oil does not circulate doesn't the same oil stay in the crankcase "forever", why don't we have to worry about that oil breaking down. I'm sure there is soemthing I'm missing, can someone please clarify . I don't have a problem, just curious. :cheers:

 

[kustomkarl]

One line is a feed line to allow the injector oil to go to the rotary valve shaft chamber. The other line allows the oil to vent and be sure no air bubbles get in the system and stop lubricating. usually what happens over time some oil seeps past the oil seals and mixes with the fuel and oil in the cylinders. That's why it needs a light oil the same as you burn in the fuel mixture. That oil usually won't break down as it is replenished as it is needed from the injector tank. I hope this explains things.

Karl

 

[bigJake]

Thanks Karl :cheers:

 

[kustomkarl]

Glad to help...:cheers:

Karl

 

[alramey]

Hi just wondering about the vent at the top of the oil tank does a line go on it or does it just look like there should be thanks alramey

 

[Dennis]

There should be no line going to it.

DAWG