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Prop RPM

Glen P

Active Member
I'm still early in my phase 1. I have found that my Hartzell CS prop on my IO-360 never reaches 2700 RPM. While orbiting at 5000' with WOT I was seeing 2650 max. I tried adjusting the prop governor but that had no effect. 1. Is this normal? 2. Would you do anything about it? 3. What might you do?

Thanks
 
What RPM are you seeing at the start of the takeoff roll? If it’s noticeably less, then you may need to adjust the internal hard stop. Otherwise, are you positive the control cable lets the governor hit the max rpm stop?
 
RPM

Hi, I have exactly 5he same situation with my IO360. I think that the prop has to be adjusted at the hub. Any other suggestions or advice would be appreciated.

Regards to all, Brent
 
An a&p's guess

If the prop is the now ordinary non-counter-weighted - spring-loaded-to-low- pitch prop, then governor oil pressure is the only thing keeping the prop rpm from going to the moon at cruise and higher air speeds. So pressure too high.

That indicates governor, cable or maybe some restricted outflow passage.

If it is a counter-weighted prop, the opposite is in effect. Pressure is needed to get rpm. Tired governor, cable, etc.

At cruise airspeeds and higher, the prop position will be well away from the low angle stop ( static rpm adj) and have no effect on max flight rpm.

ron
 
The blades should be well off the fine pitch stop when cruising at 2700 and the factory sends them out not that far off what you need for an RV. I would be looking at the governor and it may be worthwhile to call Hartzell or whoever made your governor to insure you are adjusting it correctly and there is no other issue preventing the adjustment. I have never heard of anyone having to adjust the coarse pitch stop on a hartzell installed on an RV. Many climb at 2700 though I don't know anyone that cruises at 2700.

It is also possible that you need to adjust the heim on the cable. If you were at the extreme end of travel before, adjusting the governor wouldn't be enough; You would need to adjust the heim to allow the extra travel.

FYI, break in likes high MAP. Therefore, dial the prop back at cruise to get higher MAPs. That will help the break in.

Larry
 
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Thanks, guys. I think you're right, that the cable is likely the issue. I made an adjustment today but didn't get a chance to fly it. Hopefully tomorrow.
 
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