prop lever "sticks" mid-travel w/ power on? PCU 5000 governor

[sritchie]

Hey all,

I'm posting this before going out and figuring out exactly steps recreate this, but it's troubling me and I figured I'd just ask early and lean on the good will of the group:

I was trying to calibrate my System32 today by setting power on the ground at 24"/2400, 23"/2300 etc on down. Trying for 20"/2000, I experienced a problem where the prop cable almost seemed stuck, like there was some mechanical thing blocking it. I THINK this also occurred during prop cycling at 1800rpm, this is what I can't exactly remember... but it was weaker at that power setting, almost like "huh, is there something stuck under the quadrant?"

This does not happen at all with the power off.

I'm going to go out tomorrow and try to recreate this and send exact info to the group, but I wanted to ask in case I've hit on some dangerous failure mode that folks here know about. Thanks all, first flight's getting closer once I sort out these issues!

 

[climberrn]

Make sure the radius is not sharp on the governor cable, specifically where it goes through the firewall.

 

[paulsmeds]

I had this exact problem. It was smooth pulling out from full in about an inch and then felt like it was binding up and you had to pull much harder for the rest of the travel. I received a couple of opinions and almost ordered a cable. But when disconnecting the cable from the governor both the governor and the cable moved extremely smooth. Figured out the bracket attachment was not aligned with the travel of the governor arm as it as cycled. Did some aligning and now it is super smooth. At the end of the prop cable is a shaft and when it retracts into the prop cable sheath at an angle was binding at a specific point. Was a pretty easy fix. Yours might be something different. Good luck!

 

[sritchie]

Okay, I think I've figured it out. @paulsmeds , that theory makes sense but I think mine is not too far off, as it feels good when the power's off.

The problem is that my cutout for the governor is too restrictive. At higher power on the ground, the engine is pulling forward, and the governor arm is binding as it tries to get past the fiberglass. I think if I carve it back all will be well.

Of course then I'll need to solve for blocking the huge air leak caused by the hole here... one step at a time!

Thanks all, I really appreciate the comments.

 

[bjdecker]

1. Reset the rod end bearing to be parallel to the movement/throw of the governor arm.
2. Cut a more generous relief "notch" in the inlet upper ramp.
3. There isn't an "air leak" unless the end/sides of the upper ramp are not installed per plans, page 45-20.