Just recently noticed my prop pitch control has gotten real stiff. In a run up this weekend it was almost impossible to pull out and test. In flight it is fine to adjust pitch/RPM, but in run-up very stiff! Any thoughts appreciated.

Brett

Brett,

These control cables operate through sleeves. It is possible to get contamination through the sleeves - especially as work is done in the engine compartment. They also wear. Perhaps you've already checked that nothing has recently bent the cable/sleeve and no items are zip tied to it.

Couple of options. They can be replaced. Mcfarlane had a full set of new cables for my Twin so I'm guessing they would also be available for your single but i would check that guess.

Also, folks have lubricated those sleeves - hopefully a person with the knowledge of that procedure will chime in. I had mine lubricated twice - didn't solve the problem, so i replaced. FYI. The prop cables talked first, then a mixture.

Hope this helps. Kindly post what happens. Thanks.

Hi Brett,

I don't wish to be an alarmist but the fact the control works well in flight but not on the ground is concerning. One difference between those two phases of flight is the gear is retracted in flight. There have been several crashes caused by a control cable getting fouled up with the nose gear mechanism. I would suggest a close inspection inside the cowling if this has not already been done. Did this problem arise right after work had been done on the aircraft?

Good luck, Don

Good respones/answers, it has always been a little "stiff", especially in cold weather. My A&P was actually flying with me to Talladega when it happened, so he quickly suggested probalby replacing. Nothing has been done to the plane, so no maintenance related cause and effect. In flight it is less noticable because I am dialing back RPMs in small increments, like 25-24 or so. On the gound, during run-up, I am cycling the prop as a part of pre-flight. Hope that answers that part. Let me know if anyone else had this issue, or solved this issue., btw Pat, what did the new cables cost if you don't mind.

A generous dousing of WD-40 followed by mouse milk will probaly fix the problem. Check the routing of the cable. If it is right next to hot exhaust pieces anywhere on the control run, you have probably melted the inner sleving. Once it heats up ie in flight, it moves easier because the sleve material is soft. Reroute the cable, and/or install some heat shielding to prevent the hot spot problem in the future if you find it to be the issue.
-Zach

Had the same problem with my 1960 250. Did the Zack recommended treatment using penetrating oil and all was well for the summer, come winter and back to stiff. Then one day when pulling the mixture control out for shut down it kept on coming out and there I sat with the wire in my hand. A check of the logs showed nearly 35 years of use on all three controls. I ordered new for all three but could not find all three from one source at the time. Once received and in stalled the difference was amazing. I remembered how smooth the controls were supposed to be! The new ones were also the correct length and routed correctly, made a big difference. If you have to have any of them made up call Phill at Webco he'll give you the correct lengths. The prop control was the most expensive as I recall, $200-$250, but well worth the piece of mind when flying a 50+ year old airplane. Ray B

good information, let me check routing, use penetrating oil and check for any "heat exchanges" that might affect normal use. I'll post what I find and end up doing, Thanks

Bought new, fixed

 

Mouse Milk is a brand of penetrating oil that is particularly useful for freeing up turbocharger shafts that have become coked and no longer let the turbo spin as freely as it should.

Mouse milk is also handy for reluctant nuts, bolts, shafts, etc. that we all encounter from time to time. A must in my shop.
Steen

I'll have to say that is a first time to hear about that, I may need to get some for my portable tool box I take to the hanger. Thanks George

 

Matt,

Webco,