What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Bleeding air from the prop govenor, prop etc

Ted Radclyffe

Active Member
I am about to start the O320 with CS prop. At this moment there is oil pressure indicated when turning the motor on the starter without plugs.

Nowhere do I find reference to bleeding air from the prop govenor, propeller or lines. The nearest reference seems to be to cycle the prop in the normal manner to get rid of any trapped air.

The question: Is there any reference I have missed? Has anyone loosened the forward tube fitting near the front bearing to release air?
Do I have to worry about this at all?

Ted RV-6
(90% finished 90% to go)
 
Bleeding Prop Line

Hi Ted,
I got my Hartzell new from Van's and it came with the small maintenance and operations binder, which is were I found this information. I believe it said to simply cycle the prop and the air should be out after the third time and this worked fine on ours. I'll swing by the hangar at lunch to check the manual again for you.
 
No need to bleed

There is no need to bleed the prop - oil flows through the system all the time, so will purge the air. Just make sure the pipes are tight - the oil coming out of the governor is under higher pressure than lubrication oil and will spray everywhere.

Pete
 
Cycling the prop should get all the air out of the prop. The first couple of times you go to cycle the prop, it may take longer for the prop to react then what you are accustomed to. After all the air is out of the prop and it has been replaced with oil, the prop reaction time will get more normal. So don't worry if it takes a few seconds more for the prop to drop RPM the first couple of times you try it.
Good Luck,
Mahlon
"The opinions and information provided in this and all of my posts are hopefully helpful to you. Please use the information provided responsibly and at you own risk."
 
from the manual

This is from my blended airfoil Hartzell manual:

1. Operational Tests
Following propeller installation, and before flight, the propeller hydraulic system must be purged of air and proper operation verified.

A. Initial Run-Up
(1) Perform engine start and warm-up per the POH. Note: Air trapped in the propeller hydraulic system will cause the pitch control to be imprecise and may result in propeller surging.
(2) Cycle the propeller control throughout its operating range from low to high (or as directed by POH).
(3) Repeat this procedure at least three times to purge air from the propeller hydraulic system and to introduce warmed oil to the cylinder. Note: Pitch change response on the first operation from low to high blade pitch may be slow, but should speed up on the second and third cycles.
(4) Verify proper operation from low pitch to high pitch and throughout operating range.
(5) Shut down the engine in accordance with the POH.

WARNING: REFER TO THE AIRCRAFT MAINTENANCE MANUAL FOR ADDITIONAL PROCEDURES THAT MAY BE REQUIRED AFTER PROPELLER INSTALLATION.

B. Post-Run Check
After engine shutdown, check propeller for signs of engine oil leakage.

Hope this helps.
 
Prop bleeding

Thanks for the information. I was simply not sure that I had all the information and it just seemed that there should be more to do than simply cycling the prop.

Thanks for putting my mind at ease.

Ted.
 
Back
Top