run up check question

[dmaher]

Hi, I have a few RV questions again.
I’m working on tuning the run up check in an FSX RV7 simulator.
The engine is a 180hp IO360 with a constant speed prop.
I’ve only flown a fixed pitch Cherokee so I’m a bit unfamiliar.
Here’s what I do…

Set prop lever full forward.
Set throttle for 1700 RPM; pitch goes to 15deg (full fine); MP is at ~ 15”Hg (at sea level)
Set Left Mag only; RPM drops by 70
Set Right Mag only; RPM drops by 72
Set prop lever full aft; RPM drops to 1500

Does this sound right? Do you get/use similar values?
I’m especially interested in the lowest rpm your prop governor can get.
The prop "is" a pretend Hartzell (HC-C2YK-1BF) for what it's worth
Thanks,
Danny

 

[Trevor778]

I have actually never checked the rpm drop when I cycle the prop on the cardinal I fly. But, I cycle it 2-3 times just to check that is in fact working. If you leave the prop control out the rpm will drop significantly. hope this helps.

 

[pierre smith]

My -10 has a blended airfoil Hartzell and it'll drop to 1100 RPM with the prop control full out.

Best,

 

[B Cunningham]

Here is a link to John Deakin's article on c.s. props that will be very helpful to your understanding of whats going on: http://www.avweb.com/news/pelican/182082-1.html

 

[HSANTIBANEZ]

It is no recomended by Lycoming to drop more than 300 RPM on cycle check, I made 3 checks one drop 100 to cycle oil in the prop, second 200 and third 300 with oil pressure check.

Droping more than 300 RPM with the hub out of oil can cause damage in the system.

Best Regards

 

[Walt]

I put cycling the prop on run-up in the "totally useless/could be harmful to the engine/why bother" catagory.

Unless you are testing the prop cycling it on run-up serves no useful purpose and IMO and does more harm than good by loading up the motor at low RPM when it's cold. It might sound "cool" and gives you some kind of warm and fuzzy feeling, but other than that, it proves nothing (at least on a familiar airplane that you fly regularly).

 

[dmaher]

Thanks for the answers. It seems like the governor?s minimum RPM would be in the specifications. But I?ve searched everywhere without much luck. One unnamed Hartzel example listed 1180...an example from who knows what aircraft and prop. I figure 1100 will suit the RV well.

 

[Toobuilder]

Also keep in mind that some props go to course pitch when oil pressure is released from the hub... Aerobatic and feathering propellers, for example. In this case, you will see an oil pressure drop on the indicator when you go back forward with the control and oil is sent back into the hub. Also, if you're looking for the ultimate simulation, you will also get a MP rise as the RPM drags down.

Also, if you are running an electronic ignition, you may not see any RPM drop when switching to a single ignition - the only way to tell is by seeing the EGT rise.

 

[mburch]

I guess it depends on the engine and propeller... one of the airplanes I fly (not an RV) has a recent bulletin from McCauley in the aircraft paperwork that instructs the pilot to "cycle the prop from 1800 RPM to 1200 RPM five times, during the first run-up of the day, to ensure the seals are properly seated and prevent oil leaks" (paraphrasing from memory).

mcb

 

[David Z]

Cold Oil

One school of thought that I have heard is to cycle the prop to get some warm oil in the hub and speed up the prop's reaction time when you do take off. I don't know how valid that is as I've never tested it on the same aircraft type. If you always move the throttle slowly, I don't imagine it would matter much.