cycling the prop

[woxof]

Someone on another forum posted this info which I had not heard before...There are several interesting statements made.

"Cycling the prop gets warm oil into the prop hub, but it takes more oil than cycles once. The volume of oil in the governor and the oil lines to the prop is 1/3 of the prop dome volume."
"
Cycling the prop does more than just get warm oil circulated, it is also an opportunity to check that the governor can reduce the and hold the rpm steady. Pulling the prop back to a minimum rpm and watching to see the rpm holds steady."

"On a multiengine airplane the check is also to see that the prop DOES NOT FEATHER when the prop lever is brought back just to the feather gate. I have flown more than one multi which was slightly misrigged, trying to set a long range cruise power of 2000 rpm resulted in the engine beginning to feather while running at power. The engine should run at the bottom of the green arc."

Is this information accurate?

Thanks

 

[Clip4]

Maybe. 2000 RPM is a rather low setting for cruise flight in most aircraft with CS props and the feather position is well below the position for 2000 rpm on the prop control. Would have to be really misrigged.

The warm oil in the dome is more complicated. First, the oil in the sump is usually not full operating temperature prior to take off. The dome is out front where air is cooling it and the oil can get rather thick. So to actually have warm oil in the dome you need to exchange enough warm oil. If you have a prop with a lot of hours, they may search in extreme cold weather and warming the oil will stop that. Normally a prop well below TBO does not have that issue. Honestly using semi synthetic oils I have never experiance cold weather prop problems. You also never here of this in Cirrus aircraft and you do not have the ability to cycle the prop. At least that’s my experiance.

 

[Eric Stoltz]

Remember the following is: "something you read on the innerwebs who says his name is Eric Stoltz so who knows if he be right." My old man has owned many airplanes in life. Of the 14 airplanes, 8 had a total of 12 CS props. 3 planes were on 135 certs. I have owned two planes with CS props. Back home, we used just one prop shop. It has been in business since 1951 and is still turning out props and governors. So, when the "old guy" that started the whole thing told us how to keep our props outta his shop, we listened.

I hear new Cirrii, don't have to worry about their hubs and govs since there's no blue knob.

We learned that cycling the prop is good, but there's a lot going on that needs to be looked at and ignored. There's a LOT of oil in radials, so it makes sense to move warm oil around. But our aeroplanes have very little oil in the hubs and govs. Ever take a prop off and notice the like, 1/3 cup of oil on your new sneakers? There's oil in the hub with no oil pressure, and that hub oil gets warm just as fast as all the rest of the oil, kinda. What doesn't get warm oil as fast is the gov. Since the circuit isn't open with idle and low RPM, the gov only has what oil was left from the last flight in it.

***What our prop shop told us to do and look for is not in the POH, so this isn't advice and I'm not telling anyone what to do. (unfortunately I need to put a disclaimer in here since, well, reasons ) Here's what this prop guy told this one guy I know how to do a hub/guv check assuming no feather circuit. I hear that most of our little planes have a gov that regulates about 1600 to 2700 rpm, so this may not work in the aeroplane your buddy flies. After the oil starts to get warm, and only first flight of the day/cold engine, pull prop to low rpm at idle/taxi power before programming the gps, and getting the #pilotlife selfie out of the way. When it comes time to check the hub/gov, keep the knob to full low rpm and start increasing throttle until the gov "catches" the rpm and starts to govern (about 1600 in my plane). A few seconds later, add a tad of throttle and see that the rpm basically modulates a tad and settles back to 1600ish. Push the blue knob to full fine and noice the rpm trending up, and reduce throttle in short order or do the mag check. There, done. The gov has warm oil, probably before even adding throttle, and the hub oil gets to move the blades around keeping the seals lubed. If there is a feather circuit, before one pushes the props to fine, cycle the prop levers past the feather detent just long enough to notice a trend towards feather - just a bump.

The arguments the Old Guy at the prop shop talked about were many. Some preflight prop tests in the manuals were never a prop, gov, engine manufacturer suggestion. And really more of a maintenance annual thing. His thoughts on the high rpm tests were holdovers from radial days where props where way up the air and didn't kick up crap, and needed rpm for pump pressure, had gallons of oil in the gov and feather systems, etc... Also, he noticed how much wiggling the engine did when he observed high rpm and multi blue knob pulls while the cowl was off. He thought during his watching the cylinders flex and vibe, and the mounts getting torqued, seemed like a good way to keep his neighbor the engine shop in business. His experience from OH'ing 135 props from Barons, twin cessnas, from operators that mandated their pilots do the high rpm checks was that is that those props were kinda beat up. Same from flight school props. The props from one 135 operator that had a bunch of Queen Air Excallibers and used his method of checking were in much better shape.

It was fun to tour that shop. They had an immaculately clean joint. They even vacuumed their run up pad before testing a prop on an airplane.