VintageBonanza Forum

[dong]

Just started all of a sudden, oat 35F, static rpm max 2025 mp 27.25in. At 70 MPH rpm 2075 rpm and 27.25in. I use to get at least 2500 rpm and 27-28 inches of mp.

Have checked the prop governor and it travels full from hi to low limit. Checked engine compression and its is also good. Check throttle throw and it travels to full throttle. Checked air intake, no obstuctions found.

Wondering if the rubber gromments on the prop drive gear could cause such a big loss in rpm, its possible that they are worn.

Any help or ideas would be appreciated.

Thanks,
Don
1947 Beech 35
E-185-11
Beech Elec. Prop

[bgwells]

Do you have the solid state prop governor? During take off, have you toggled the prop to hi RPM setting and not let the switch go to AUTO mode? It just seems a big jump or difference in RPM. Do you have the Automatic governor or is is just manual control? Seems like we have had this question before? When has the prop been off to grease the prop bearing, hoe man hours ago and how many months/years?

[dong]

BG, Sorry it took so long to reply. We have both the manual and auto propeller control. The toggle switch has a position for HIGH/LOW/NEUTRAL/AUTO. We made sure that it is not a switch issue, like going into auto mode. We have done a number of other checks on the prop and engine, (low compression, carb, throttle, mixture.) Checked the prop gear for full travel and stop micro switches. The last greasing was approx, 200 hours ago, 2 1/2 years ago. We pulled the prop and checked the bearing grease, it was still well greased (we did not pull the bearing). We checked the high prop pitch and found it at 15 degrees. It should be 13. We replaced the grommets. We will start an annual on Feb. 1, 2010 and re-index the prop to 13 degrees. If that doesn't fix the problem we will take it to a prop shop in Michigan (I'll have to get the shops name) as we found a man who is well versed in Beech props.

[bgwells]

Would also make sure everything on the carburetor is working, there is a power valve that sometimes sticks, and I used to have to clean and use some lubricant on that too. I think you will find that on the left side.

[dong]

We found the problem. We really lucked out finding this before any damage took place. I'll try to explain this as best I can. I will be referring to the diagram at this link. The 215 Prop Manual. Go to page 14 to see the diagram.

http://www.vintagebonanza.com/docs/215-manual.pdf

With the prop still on the plane we noticed there was a little movement in the pitch when we turned it by hand. There are two actuator CAMS (32) that run through the hub to the actuator bearing assembly (28). One of cams would move when we twisted the prop showing that it was loose. We thought maybe it had broke.

We pulled the prop and prop motor assembly. On a work bench we followed the procedure for removing the prop bearing. This gave us access to the 2 castle nuts (16) on the inside of the actuator bearing assembly. They should be locked with cotter pins. One of the nuts was missing the cotter pin and the nut had backed off a few turns.

We were lucky in our case as no wear appeared on the CAM. We checked around for new castle nut and found out these are special machined nuts and would cost us $1200.00 each. Beech has them. We decided to use the same ones.

We cleaned the prop bearing and re-greased it.

You must follow the directions for replacing the actuator bearing assembly to the letter. Otherwise you will be pulling the prop off again.



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