Resolved Stiff elevator rigging - Carbon Cub FX-3

[Neal]

When I picked up my new Carbon Cub FX-3 in early October I noticed the elevator movement up/down during preflight seemed like something was rubbing/binding. Two years ago the DAR found the elevator cable off of the pulley below the pilot seat area. Good catch on that DAR who did a thorough job of inspecting. This year's DAR was different and far less thorough, sadly. I asked several at CubCrafters about this concern as my prior FX-3 did not have this feel on the elevator travel. I was extremely concerned on the ferry home to the point I almost grounded the airplane for this at Alpine, WY but had a hunch nothing would be found and this just the way this airplane is. Someone at CubCrafters mentioned it may be "new tension" or the old plane may not be at correct tension, on and on. I got home and even as recent as yesterday I pulled off panels and inspected. It's driving me crazy.

Then the thought occurred to me what the problem could be and today prior to flying I verified the problem. GAP SEALS. I pulled the gap seals out and sure enough the problem immediately went away. The problem is the gap seals were not cut to the proper length so they were compressed side to side to fit in the gap. The gap seal based on its shape will compress when the elevator moves up or down but if the material is further compressed then it will make it even harder for the gap seal to compress from control movement. I trimmed the affected gap seals and now it's exactly the way my prior plane was. Such a simple trivial item but if not installed correctly can give a feel of control binding.

FYI

P.S. Gap seals are an interesting concept, seems there are far better ways of keeping air out of that area than stuffing "weather stripping" material in the gap itself.

 

[viator092]

I flew a Grob 115 that had a thin tape material attached to the stab that overlapped onto the elevator. Flew through some virga. The elevator control froze up.

 

[BiggieN143AE]

Neal - disconcerting news prior to starting a build

 

[Neal]

Neal - disconcerting news prior to starting a build

Nothing to be concerned about. Not many get the opportunity to fly multiple FX-3's for example unless you're at CC, TacAero, ferry pilot, etc. Let's rewind to when I got my first FX-3 in Aug of 2021. I hadn't flown for 20 years other than TW endorsement and TacAero one week course. I also was not proficient in glass panel aircraft. So I was overwhelmed with simply making trees bigger and smaller and not dealing with Garmin stuff, knowing what was going on with the engine and CHT's, much less flight controls. Fast forward two years later and 200 hours in type. I takeoff out of Yakima and notice high CHT's, only about 18 hours on the plane, one is pushing 420. Elevator stiff in preflight, several checked it, said nothing seems unusual. Pete said he flew it during fly off and didn't notice anything odd. It is simply the difference in airplanes and my first plane may have been like this and I didn't know it, I couldn't tune into something like this back then. It's probably just new stiff rubber material that will loosen up as it flexes from compression and use. I flew two different FX-3's in my TacAero training, the yellow bird had stiff controls, Specter did not, it was very noticeable and we discussed it. Probably a difference in rigging, who knows.

So again, just more aware with time in type yet no real experience in various planes caused me to be hyper sensitive about the new plane both in engine readings, Garmin stuff, and the flight controls. The CHT's are noticeably better now that the engine is broken in. Interesting to see and comprehend it this time around. I still struggle to have confidence in experimental anything coming from my military background and extreme attention to detail of military maintenance.