Online Community of Zenith Builders and Flyers
I have wondered the same thing. However, a lot of Zeniths have flown a lot of years with the plastic block fairleads and not had problems. I will most likely stick with the plans - simple, effective, weighs less. I await input from those who have been flying as to the longevity and reliability of the stock fairleads.
Since no one has yet responded about using pulleys, I guess I am going to chime in like Bob did and say the current design is working for me. 4 years, 221+ hours and over 500 landings and I do not have any real nylon fairlead wear to speak of. Regardless, I check the cable tension by feel prior to every day's flying and with a tension gauge at every oil change. To date I have never had to re-tension anything in my control system due solely to operational wear. Since nylon fairleads are only meant for light angles, 7 degrees or less, if I recall, they should not be under a huge wear load. For now I would recommed sticking to the plans.
Thanks Bob and Dave!
That's all I need to know, it sounds like it is a complete non-issue and I don't need to waste time thinking or worrying about it. I was more curious than anything, since I am a complete aircraft newbie. I've been surfing a lot of different builder sites and other resources, and see a lot of talk about phenolic pulleys, etc. - those are probably meant for much more radical shifts in cable direction.
I will be making up pulley frames and having pulleise where possable. Wires rubbing on plastic is not for me nor is it ok for Cessna or Piper. I am building a Ch650B. I will not be doing any cable fairlead work untill finished fus it needed.
Nearly 300 hrs on a 750 and so far I can't detect any wear on the fairleads - controls are nice and smooth!
I've seen a pulley put in the top rear fuselage for the elevator upper cable. If there was one that was needed it would be there! I just tensioned up my cables and I don't like the feel of that cable rubbing on anything so I wish I would have put one there. :( There was a picture here somewhere of somebody who thought the same and put a pulley in that spot...
Besides that I don't think they would be needed anywhere else, and like everyone else has stated there haven't been any issues that have come up!
I agree, look at how many nylon fairleads a Piper J3 Cub has just on the struts. They've had 65+ years to determine if wear was an issue, so I'm comfortable with that test period. Simple and light.
I ended up using the oil fill nylon for the rudder and elevator cables. For the wings i used push pull rod, so no wires.
My take is that even if you are using a pulley to guide the direction of the cables they are in many instances passing thru a relativly small hole in the aluminum skin and would be at least intermittently contacting the aluminum. the nylon fairleads will prevent that and protect the aluminum and the cable.
I went all through this with the A&P that did my conditional. I even went so for as fabricating pulley's for my elevator cables until my local DAR set them straight. I did make some new fairleads out of 1/4" oil filled nylon from McMaster carr that made everyone happy,, but wasn't really required or needed
I had an IA look at my rudder cables and he recommended using a plastic bushing at the front fairlead hole. Instead I used a 1ft length of brake line over the cable. This slides thru the hole very smoothly and hopefully solves any future problems.