throttle stuck at idle position - very humid weather

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A2022
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throttle stuck at idle position - very humid weather

Post by A2022 »

I pulled the plane out for a flight, but the throttle was stuck at the idle position. no force could move it, so I removed the throttle cable to have a look at it. it looked good with the sheathing fully in place, no signs of heat. again, no force could move it. it has been hot and humid lately, so I took the throttle cable home to put in a de-humidifier. 2 hours in the de-humidifier, no change. 4 hrs in the de-humidifier and the throttle broke free and was easy to move. time for a new throttle cable and I need to have a spare on hand. note: this cable is 2007 vintage and 1000 hrs of operation.

edit: after the cable has been in the house at a relative humidity of 50% for 14 hours, the cable operates perfectly with no indication of impending failure. I thought about re-installing the cable and departing for a planned camping trip to Michigan but what if it rains? or the cable develops another problem because of some unknown internal defect, so no. the throttle cable is a critical safety item. I'll install a new one.

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Steve Melton
N531EM, RV9A, Superior O-320, WW 200RV prop, Slick mags, CHT 330F, EGT 1300F, B&C, 1200+ hours
Freedom and Democracy are all that really matter.
Ride a bike, unlock the world.
https://www.rvplasticparts.com/
https://www.gpsdock1.com/

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A2022
Class B
Posts: 1136
Joined: Sat Mar 05, 2022 8:52 am
Location: Cincinnati, OH
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Re: throttle stuck at idle position - very humid weather

Post by A2022 »

a neighbor had a spare throttle cable so that was replaced today, and I had some good help. it was easy to swap the throttle knob. I just can't do the standard black plastic knob anymore. I think it would be good to have some spare cables on hand so that you're not grounded waiting for shipping. I plan to have a spare set in the future.

the daughter refurbished an antique espresso machine. it works!

cool weather, nice music and a good time working with ones you love. a very good day.

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Steve Melton
N531EM, RV9A, Superior O-320, WW 200RV prop, Slick mags, CHT 330F, EGT 1300F, B&C, 1200+ hours
Freedom and Democracy are all that really matter.
Ride a bike, unlock the world.
https://www.rvplasticparts.com/
https://www.gpsdock1.com/

User avatar
A2022
Class B
Posts: 1136
Joined: Sat Mar 05, 2022 8:52 am
Location: Cincinnati, OH
Contact:

Re: throttle stuck at idle position - very humid weather

Post by A2022 »

as I prepared to dissect the old throttle cable a week later, I noticed something on the barrel where the rod end connects to the carb. the substance was a thin line of VC-3 thread lock. I could barely see it. apparently, some had strung across the actuation barrel unknown to me during condition inspection. the engine had been run and cycled to run up power after the condition inspection and I thought it was good to go. high temp and humidity in the hangar swelled the VC-3 on the barrel and completely locked it up. removing and drying the cable freed it to be like new condition. I threw the cable in the trash. I don't want anything on a cable. note this cable did not have a rubber boot a rubber boot at the barrel. it was 2007 vintage and 1000 hrs. my takeaway, is to be careful and not get anything on the actuation barrel of the throttle cable. keep it very clean. it is a closer tolerance fit than you think. I didn't take any photos.
Steve Melton
N531EM, RV9A, Superior O-320, WW 200RV prop, Slick mags, CHT 330F, EGT 1300F, B&C, 1200+ hours
Freedom and Democracy are all that really matter.
Ride a bike, unlock the world.
https://www.rvplasticparts.com/
https://www.gpsdock1.com/

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