Throttle Quadrant Friction Change Question

[rvanstory]

Today I took 1st flight after my annual condition inspection to test for normal operations. I also did a SAVVY FLIGHT PROFILE to double check GAMI spread and ignition health.

BUT... for the first time ever (480 hours on engine) my prop control kept creeping up. My throttle quadrant has alway been super smooth and "easy" to move for all three controls (throttle, prop & mixture). But today, my RPM kept creeping up. In order to keep the RPM constant, I had to tighten the friction knob to the point that the mixture was SUPER tight, but RPM was "snug".

Not sure what could have changed??? Only thing I did was lube bearings, but I've this every year.

Anyone have any thoughts on what may have changed after 4 years. I really liked the fact that my controls were smooth and easy without creeping off settings during flight. Is there any way to adjust individual levers so one can be tightened (RPM) without affecting the others (mixture, throttle)?

 

[Ron B.]

They should all tighten up evenly. They are all made the same with the same bushings. Any chance oil or some other type of lubricant hit the prop bushing only?

 

[fl-mike]

Reduce the spring force on the prop gov, or buy the “formation” quadrant with separate friction knob for the throttle.

 

[Ron B.]

If it didn’t creep for the first 480 hrs. , then the governor spring force should be OK. Springs don’t get stronger with usage. Something else changed. Just my opinion.

 

[rvanstory]

Reduce the spring force on the prop gov, or buy the “formation” quadrant with separate friction knob for the throttle.

Thanks Mike. Can you tell me how to reduce the spring force on the prop gov? Is there some adjustment? Replacement? Not sure how one can do this.

 

[rvanstory]

If it didn’t creep for the first 480 hrs. , then the governor spring force should be OK. Springs don’t get stronger with usage. Something else changed. Just my opinion.

Totally agree!!! That's why I'm puzzled. I can't even imagine what else could have changed. That's why I was hoping someone else has experienced the same thing. Maybe they would offer a clue.

 

[HFS]

Have You Considered ...

that the problem may be with the quadrant, and not at the other "end"?

The "faces" of the friction lock discs could have somehow become compromised to a lesser resistance position - thereby reducing the "locking" aspect of that particular lever.

Just a thought, obviously, but still the quadrant is part of the "equation"

YMMV - And this probably won't help, but it never hurts to consider.

HFS

 

[Ron B.]

that the problem may be with the quadrant, and not at the other "end"?

The "faces" of the friction lock discs could have somehow become compromised to a lesser resistance position - thereby reducing the "locking" aspect of that particular lever.

Just a thought, obviously, but still the quadrant is part of the "equation"

YMMV - And this probably won't help, but it never hurts to consider.

HFS

The quadrant is my suspect.

 

[rvanstory]

The quadrant is my suspect.

Reporting back that Ron B hit the nail on the head.

Went out yesterday and pulled the console out (again) to get access to quadrant. Couldn't see a problem, so decided to lube the bushings again. This lube made the mixture much easier to move when the friction lock had tension on it.

I THINK what happened is I must have missed lubing the mixture bushing at annual. So, with other two levers lubed, the difference made the mixture much harder to adjust with tension in the friction lock.

Didn't get to fly yet, but 99% sure this simple oversight was my problem all along.