What were they thinking - airplane rigging edition

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k9medic

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ATP-H, CMEL, CSEL, CFI/CFII Airplanes and Helicopters
Thankfully as of right now, the only issues that we have to deal with on our new to us Cherokee 6 are small ones.

One issue that we have noticed is that the plane almost always needs right yoke deflection to fly level. This of course then leads us to need to put in left rudder, which in turn slips the plane.
The plane has a fixed trim tab on the left aileron and an Aero Trim set up on that same aileron as well.

Today, after leveling the aircraft, squaring the yokes and manufacturing a flap and aileron rigging tool, we ventured into the mechanical world of trim. Here is what we found:

Left side aileron is rigged too high. - reducing lift
Left side flap is rigged too low. - creating lift

Right side aileron is rigged too low. - creating lift
Right side flap is rigged too high. - reducing lift

Our mechanic is stumped as to why anybody would rig an airplane this way. His plan is to return everything to nominal (except for removing the riveted fix trim tab) and go from there.

Are there any 6 Guru's that might know what was done and/ or why?
 
Prolly people not knowing how to do a proper rig on the a/c. We had an SF-260 that would get heavier on the ailerons as the speed went up. Chased that for a day or two before we made the decision to run the entire rig process. Found the forward inter-tie cables for the ailerons so far out of wack that the bellcranks were canted inward about 30 degrees with the ailerons and stick in neutral. Rig calls for them to be parallel within a certain amount. Corrected that and some other minor rig issues and the a/c was back to flying like a sports car rather than a brick wagon.
 
Have seen a 172 with a fixed aileron trim tab installed, bent to around 70° up, lol.
 
I would be resetting all the surfaces you mentioned back to nominal to start. I am not familiar with Cherokee 6"s, but the smaller ones I know didn't have any fixed tabs. And what is an Aero Trim setup?

Edit - I see the aero trim now. I had no idea something like that was available. Something else to check the rigging of.
 
The aero trim is simple to “reset.” I just run the switch on the electric motor until the trim tab is level.

Pretty nifty device actually.


Sent from my iPhone using Tapatalk
 
Of the six airplanes I have owned not one of them was properly rigged when I bought it. It's one of the first things I attend to. The five Pipers varied from "not too bad" (Aztec), to "wtf". The Husky was the closest of them, but it is also the newest and by far lowest hour plane I've owned.
 
You might reset everything and go through the complete rigging procedure.............and it will be worse.

Most of the Cessnas and Cherokees are antiques......and who knows how bad their various parts have been "tweaked" by windstorm, crash landings, hangar collapses, runaway hand propping,, landing in the river...............etc. Any fuselage tweak will nullify the book procedure.
 
Let'sgoflying! said:
Have seen a 172 with a fixed aileron trim tab installed, bent to around 70° up, lol.
Click to expand...
I saw a Maule with a fixed tab added just above the adjustable tab on the rudder...apparently adjusting the existing tab was too complex. :rolleyes:
 
The plane this made me think of had, at some point, run into a tree while taxiing, and it tweaked the wing enough to give it a permanent yet not really visible twist. However, when you flew, you could feel it. They put a fixed aileron trim tab on it, but that really only worked at one speed, otherwise you were always working to keep it level. It always dropped a wing when stalling. It had a Juliet in the tail number, but we all replaced that with "Junk" when talking about that plane.

Eventually, a new pilot forgot to check controls free and correct and didn't notice the nail that was holding them in place. Luckily for his pax, he noticed it as soon as he left the ground and immediately pulled power so the crash resulted in only minor injuries. Plane was totaled.

However, someone bought the wreck and was going to rebuild it. Since I had posted about that airplane with the tail number, he found me and asked me about it. When I mentioned its tendency to imitate a corkscrew, he said "I'll just install a Crown Royal autopilot." (me: Huh??) "Oh, you just take the little purple drawstring bag from a bottle of Crown Royal, hang it from one side of the yoke, and fill it with marbles until it flies straight." :rofl:
 
Well I was able to make some flights to evaluate the adjustments. First flight with everything neutral caused a roll to the left. The left flap was adjusted down per the manual and it flew a little better on the second flight.

Due to other scheduling, we didn't have enough time to do a third flight so we will have to wait to see about more adjustments next week.
 
MauleSkinner said:
I saw a Maule with a fixed tab added just above the adjustable tab on the rudder...apparently adjusting the existing tab was too complex. :rolleyes:
Click to expand...
The Maule's rudder tab is usually operated by the aileron system, not by a trim wheel. It counters adverse yaw. It has to be rigged by loosening the clamps that connect its cables to the aileron system up in the headliner, a really rotten place to work, and you have to hold the aileron cable with one hand and pull on the rudder tab cable with the second hand and hold the clamp with your third hand and tighten the clamp nuts and bolts with your fourth and fifth hands.

Now you know why someone stuck a fixed tab on that rudder.
 
Dan Thomas said:
The Maule's rudder tab is usually operated by the aileron system, not by a trim wheel. It counters adverse yaw. It has to be rigged by loosening the clamps that connect its cables to the aileron system up in the headliner, a really rotten place to work, and you have to hold the aileron cable with one hand and pull on the rudder tab cable with the second hand and hold the clamp with your third hand and tighten the clamp nuts and bolts with your fourth and fifth hands.

Now you know why someone stuck a fixed tab on that rudder.
Click to expand...
No, I don’t...I found it a fairly easy adjustment on mine.
 
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