Leaning Left, and that's just not right!

[Bruce Fenstermacher]

For those contemplating adjusting the eccentrics I want to point out that you must check aileron and flap cable tension afterward because changing the eccentrics will loosen or tighten both of the cables.

[GAHorn]

So Del I've been meaning to ask. When you adjust the eccentrics to neutral which way should it point. Inboard or outboard?

I'm thinking all red 170s have the eccentrics pointed in to impart a slightly sweep wing configuration and thus help with sub sonic stability. George am I right?

Normally outboard. I've had problems on all 170's and most other 100 series of early vintage trying to turn them inboard. I think you'll find on your 170, if someone has ever turned them to the inboard neutral position, there will be a dent, crease, or puncture on the wing root ribs from the fuselage carry-thru channel contacting them. Later models don't have this problem, and I've never studied why.
Standing at the rear of the aircraft looking forward, the left eccentric typically will allow contact between the 2 and 4 o'clock positions, and the right between 8 and 10 o'clock (these are approx positions, I quit attempting going inboard after discovering damaged ribs and learning why). At these positions, it not only contacts the wing rib, it would also put some extra shear load on the bolt.

Pointing inboard or outboard..... Are we viewing from the front or the rear?

[cmsusllc]

Thanks guys for all your input. This weekend I'm going down to the hanger with my smart level, straight edges and shims to properly measure the wash out on the wings. I'll report back with what I find.
Scott

[cmsusllc]

Well ---- I'm still looking. What is the wing washout suppose to be? My understanding is 2-1/2 degrees. The left wing
( heavy ) measures 2.6 degrees. The right ( repaired ) is 2.4 degrees. Also how much difference should there be between the wings at the rear spar adjustments when fully adjusted in opposite directions? Mine are about 3/16 inch, measured by string line on top and the difference where the spar enters the box on the bottom.
My plan now is to remove the rear attach bolts to check the excentrics ( now that can't be spelled right ) and their offset and position. It sure looks like they are opposite to me, and two other A&P's.
????? Scott

[GAHorn]

Don't remove the rear attach bolts to check the eccentric positions. (And if you move those eccentrics be certain to keep them moving together...so as to not bind them with the bolt.)

[Bruce Fenstermacher]

Why not remove the bolt George. I personally wouldn't do it but what harm could come if done properly?

[Bruce Fenstermacher]

Scott I'm trying to understand the data you gave us on the wing washout. Does the left wing (the heavy one) have more or less washout?

Without knowing what exact equipment you used and how careful you were (i'm sure great care was taken) I might think that your measuring could have an error of .1 either way and in that case the wings could be pretty much the same. On the other hand the difference could be a clue as to at least part of your issues.

[GAHorn]

Why not remove the bolt George. I personally wouldn't do it but what harm could come if done properly?

I'll take that as a rhetorical question, as I'm sure you and I both know perfectly-well that there is no need to remove the bolt to inspect eccentric position, which is his stated purpose. (Yes, we also both know that bolt-removal will not make the wing fall off as long as the eccentrics are not disturbed.)

[Bruce Fenstermacher]

I did not mean it as a rhetorical question. Yes I knew you can inspect the eccentrics without removing the bolt and that the wind would not fall off with the eccentrics in place but I couldn't remember any harm that could be done assuming someone does not use a 10 pound hammer to beat the bolt out.

Just the way you bluntly said "don't remove the bolt" I was thinking I forgot something.

[cmsusllc]

What I've noticed is that with the eccentrics adjusted to their extremes their is not as much difference as I would expect. The reason for removing the bolts is to check the actual offset and making sure someone hasn't modified something. And yes George I know they must be moved together, thanks for the advice anyway.
To measure the washout I used a straight edge with stand offs clamped on in order to check rivit heads at front and rear spars. I checked several places to verify I was getting a good reading using a smart level. The left ( heavy ) wing has more washout than the right ( repaired ) wing. Left- 2.6 degrees, Right- 2.4 degrees. Left eccentrics adjusted full down, Right adjusted full up, measured difference as best I can is 3/16".
As long as I've gone this far with no results I'm trying to leave no stone left unturned before learning to live with it.
Thanks for all your input. Scott

[Bruce Fenstermacher]

Scott, was the washout measured comparing the wing tips to the center of the wing or even the wing root or is it comparing each tip to the other?

If each tip to the other is this with the eccentrics neutral or with the adjustment you described.

If tip to tip with the adjustment then the washout difference is even worse and you can't adjust it out as there is no more adjustment and you will have to live with it or repair the incorrect wing.

I would believe the total eccentric adjustment could be 3/16. It is not very much and can't really be seen unless you compare closely the wing root and the fuselage wing fairing before and after an adjustment. I would highly doubt anyone changed the eccentrics in fact you may be the first to fool with them since the factory when new.

I live with my heavy left wing by keeping more fuel in the right side and or loading the right side heavier.

[Metal Master]

For what it is worth I posted this a year or so back and found it his morning.
I have a spinning laser that will place a laser chalk line around a room if the room is empty so that noting is in the way of the laser. In the hanger with the Laser set on a tripod so that the chalk line would shine on the leading edge center line. I raised the tail so that the bottoms of the wings were leveled for and aft with a carpenter’s level set on the bottom of the wing just out board of the lift strut. Then I checked the aircraft level laterally across the seat rails and upper door frame as two references. Note this is not necessarily the level flight attitude.
Then I hung targets from the leading edge at the inboard wing leading edge, just forward of the lift strut leading edge and at the wing tip just inboard of the wing tip and about 14 inches inboard of wing tip at the second to last rib. I did not look up the station numbers. I also hung targets at the trailing edge of the wing at the same location just forward of the flaps and aileron. I adjusted the laser so that the chalk line would appear on the leading edge. The inboard section of the wing in the A model has no dihedral so the laser line appeared right down the centerline of the leading edge to the wing strut. The wing has taper built into it as the ribs get smaller from here outboard. The laser line could be measured down from the leading edge at each station and compared from side to side. I then lowered the laser down so that the chalk line appeared about ¼ of an inch below the inboard trailing edge. I then was able to measure the distance from the skin down to where the chalk line appeared below the trailing edge at each station out board from the wing attach point. In both cases the laser was placed in front of the aircraft at the center of the aircraft.

Note this was probably all over kill for the needs and the first time I ever tried this after rebuilding a set of wings. I made no adjustment from my findings from the laser check because it showed both wings at exactly the same position which completely surprised me.

There is a funny part too all this. When I first turned on the laser I had it positioned it so that the chalk line appeared completely around the hanger above the airplane. As I lowered the tripod with the crank to position the chalk line on the leading edge the first time the chalk line disappeared. I thought something was wrong with the laser. I checked the switch and the batteries. I started over with the laser back above the aircraft. Every thing seemed fine. I started to lower it again when it got to the leading edge the chalk line disappeared. I checked the switch and batteries again. I started over. The same thing happened. Then I looked up. The laser was being refracted all over the hanger by the reflective surface of the wings. I had polished the wings. DUH! It was quite a light show although not moving. After that I put masking tape around the leading edge to act as a target along with my hanging targets.

Jim

[Bruce Fenstermacher]

Scott one more thought I had later this morning is that you could substantiate your findings of the left wing having more washout by doing a series of stalls. The right wing should always drop first when stalled in trim and wings level.

[GAHorn]

Scott one more thought I had later this morning is that you could substantiate your findings of the left wing having more washout by doing a series of stalls. The right wing should always drop first when stalled in trim and wings level.

Many perfectly-rigged airplanes will consistently drop the right wing first due to rudder-application at high-attitudes with power applied. For this, and other reasons, I'm not sure that this would be a reliable test to confirm the wash-out construction of any wing.

Also, keep in mind that washout only occurs outboard of the strut (sta. 100). Any other wing irregularities might be contributing factors to a heavy wing.

...I live with my heavy left wing by keeping more fuel in the right side and or loading the right side heavier.

Have you considered mounting something on the right hard-point?

[Bruce Fenstermacher]

Many perfectly-rigged airplanes will consistently drop the right wing first due to rudder-application at high-attitudes with power applied. For this, and other reasons, I'm not sure that this would be a reliable test to confirm the wash-out construction of any wing.

OK this is true so do the stalls power off. I wouldn't call it a conclusive test just more interesting information.

Also, keep in mind that washout only occurs outboard of the strut (sta. 100). Any other wing irregularities might be contributing factors to a heavy wing.

I concur and stated an example of what I believe is the case with my wings much earlier in this thread.

...I live with my heavy left wing by keeping more fuel in the right side and or loading the right side heavier.

Have you considered mounting something on the right hard-point?

Yes George I am seriously considering something along those lines at least temporarily to test my theory. I considered hanging a cloth streamer from my right strut to counter the drag I believe is being caused on the left wing by the low aileron and flap bottom leading edges. But recently I've considered how I can easily and temporarily reduce the drag of the left wing with fairings and other trick aerodynamics. If I ever do it I will report back with the results.

But rockets would be so cool