CS Prop Install Question

[robcaldwell]

Rookie question... I've completed the installation of my Hartzell Trailblazer CS Propeller. I followed the instructions in the Hartzell Manual. Tightened the nuts on the hub in a criss cross fashion, 1st pass at 40 ft lbs, 2nd pass at 60 ft lbs. All good there.

The manual calls for a "Air Charge Pressure Check", but explains little about the process. Anyone know about this?

The manual also discusses the initial operational test, but I find it odd that there is no detail about priming the hub with oil. And there is a CAUTION about "Air trapped in the propeller hydraulic system will cause the pitch control to be imprecise and may result in propeller surging". So.... How does oil reach the prop hydraulics initially? Especially on a new system such as mine that dry at the moment? (I have confirmed with Lycoming that my engine was set up for a constant speed propeller.)

Looking for more linear instructions pertaining the initial CS prop installation and operation.

[Steve W]

I gather the engine is fitted with a governor? The governor provides regulated oil pressure to the hub. If you oil prime your engine by cranking over several times for 10-15 seconds (allowing a cool down time) with the upper plugs removed noting oil pressure rise, oil is al ready entering the cavity at the front of the crankshaft. It doesn’t take very long after starting before there is enough oil to operate the pitch change. The air will purge out of the hub after the engine has stabilized and the governor is cycled 3-4 times. That’s my experience. From two short starter rotations on mine without the prop mounted, there is a couple ounces of oil already in the crank flange hub.

[robcaldwell]

Yes, the engine is fitted with a governor supplied by Hartzell.

My Sky-Tec starter is placarded with a warning to never crank more than 10 seconds.

"Upper Plugs"... referring to spark plugs?

[Bdflies]

Rob,
The part about "air charge pressure check" has me puzzled. The propellor is controlled by oil pressure fed to it through the crankshaft. The first time you cycle the prop, the governor will direct engine oil to a passage leading to the crankshaft that leads to the hollow nose of the crank, where the prop is attached. That oil will move a piston in the prop that twists the blades. This oil doesn’t flow 'through' the prop, rather it moves to pressurize the hub (to increase pitch) and back to the governor, as pitch decreases. (Note: this explanation assumes we’re not talking about aerobatic props, which decrease pitch on pressure increase. Feathering props also have idiosyncrasies not pertinent to this conversation, unless this thing feathers..... ?? Remember that air charge thing?) The in /out movement of oil will purge air from the rear of the hub. That’s why it’s so important to cycle the propellor before flight.
As long as you lubed the crank nose and the o-ring in the prop and didn’t damage it during installation, you’re good until startup. I 🤔. Air charge? Can that thing feather??

Bill

[jaredyates]

The first time I run the engine after it has been sitting for a while, it takes a few seconds between pulling the blue lever back and getting the blades to bite. But once I cycle it a few times, it's good.

[Battson]

I didn't do anything special, after fitting mine. No air pressure test was required in our reading of the manual, things maybe changed since then...?
We just did the thing Jared describes and all works well. We kept an eye on in during the first full power run and flight, in case of surging. There was none.

[keefer66]

just researched this. air charge pertains to the -2 and -5 props, and they are the feathering type. page 4-7 in the 115n manual. https://hartzellprop.com/wp-content/...000-R23-WA.pdf

[robcaldwell]

keefer66 I received the 145 manual. https://hartzellprop.com/wp-content/...000-R18-WA.pdf . Mine is the "R" flange.

Safety wire is also mentioned in the Tooling section (page 3-3), but nowhere does it detail what gets safety wired...

Bdflies keefer66 Page 3-7 discusses the "Air Charge Pressure Check". Is not mine a 2 propeller? Maybe I am confusing this with 2 blade?

[Battson]

We noted the safety wire requirement. Normally I would hesitate, because the wire can vibrate and eat into the part, however in this case we needed to comply so I have safety wired the prop attach bolts by running safety wire through the roll pin holes, using 0.032 wire.

[robcaldwell]

Battson Do you have any pics of that Jon?

Mark Goldberg Good point, Mark. I have a tentative appointment to have an A&P come out next week. I will say.... I have had a very difficult time finding a A&P that would come out and look at my engine. I live in a major metropolitan market where there is no lack of aircraft mechanics. However, as soon as mention that I am building an experimental, they all find an excuse not to take a look at my project. One even said he was not comfortable looking over a project and engine that was not professionally installed.

[Battson]

I don't sorry.

[Steve W]

Yes. Upper spark plugs out. Without the plugs in, the starter is not under any duress or load. The “nut bolts” that you torqued down the prop hub with, should have roll pins that lock the nut to the stud so you can use the hole through the roll pin to lock wire two bolts to each other.
As Mark suggests, maybe have someone with the first hand knowledge look at what your doing.

[Rollie]

I think the manual covers several models of propellers, some of which are air charged. My trailblazer doesn't have air so nothing to check there. A normal run-up where you cycle the prop several times will purge the air out of where the oil goes. Maybe do a couple extra prop cycles before the first flight. I kinda forgot that part before my first flight and it had been a couple months since my first engine start during which I had done a full run-up including cycling the prop. Maybe that one run-up wasn't enough to get the air out or maybe the oil drained out of the prop in the couple months between that and the first flight. Shortly after takeoff, climbing through about 75 feet my prop surged, to a lower rpm, sounding like I was losing power but the plane kept climbing, etc. The prop did that a couple more times then everything was normal. Could have been avoided if I would have cycled the prop during run-up. Would have made the first flight much less exciting. I was focused on all the other first flight things and on not running the new engine too long before takeoff (break in advice from engine guy).

I hadn't made a checklist prior to that first flight, one of the things that kept getting put off. I had a list of things I wanted to check during that flight but not a normal checklist. I made one before the second flight. I recommend making a checklist and following if for that first flight, you will have a lot of things on your mind and it is easy to miss something as simple and routine as a proper run-up. Your first flight will be exciting enough without adding an unexpected rpm drop on climbout into the mix.

[Bdflies]

I read this with a big grin. I was well aware that my prop required a few cycles. I'd noted this before that I HAD TO CYCLE IT before takeoff. On the first flight, out of my -short- strip, I failed to cycle the prop... As Rollie suggested, a surging engine, on takeoff, adds unneeded excitement to ta first flight!

Bill

[Battson]

Good safety-share, Rollie.

[izzo.umberto]

Rookie question... I've completed the installation of my Hartzell Trailblazer CS Propeller. I followed the instructions in the Hartzell Manual. Tightened the nuts on the hub in a criss cross fashion, 1st pass at 40 ft lbs, 2nd pass at 60 ft lbs. All good there.

The manual calls for a "Air Charge Pressure Check", but explains little about the process. Anyone know about this?

The manual also discusses the initial operational test, but I find it odd that there is no detail about priming the hub with oil. And there is a CAUTION about "Air trapped in the propeller hydraulic system will cause the pitch control to be imprecise and may result in propeller surging". So.... How does oil reach the prop hydraulics initially? Especially on a new system such as mine that dry at the moment? (I have confirmed with Lycoming that my engine was set up for a constant speed propeller.)

Looking for more linear instructions pertaining the initial CS prop installation and operation.

Hi Rob

The first check could be the pressure check of the nitrogen px if it is the case you should have a thread valve in the front of your propeller hub (used to counteract the oil pressure)

The caution refer to air trapped in to the hydroulic lines thats usually solved by cycling the prop several times during your first engine run.

Sorry for my english I hope is clear enough for you

[izzo.umberto]

Check your propeller. For example I just bought a prop hub out of a crashed seneca 1 and I have nitrogen chamber on mine.