Been reading all about excentric bolt on the forum, but looking for indication as to how much to give to correct a low left wing condition. Bolt appears to be at max down position on left wing while right wing is somewhere on the high side. Where is the reference on how much to give or take? Anticipated thanks for your help
Sounds like it's already got all the correction in for a heavy left wing. Mine is the same way.
You need to figure out why the left wing is heavy. We will assume you have the same amount of fuel in both sides and cabin loading is about equal left and right.
First look at the flaps and make sure that they are adjusted to line up with the fuselage fairings both sides.
Then adjust the ailerons to line up with the flaps.
Are you in trim? Is your needle and ball installed level with the airframe? To check, level the airframe by placing a level across the seat rails and check the ball is centered (you may also need to raise the tail so the top of the door opening is level.) Adjust the ball if needed by slightly egging out the mounting holes will a small fill. It doesn't take much. After this is checked then adjust the rudder trim tab for trim flight.
Actually the proper sequence would be to check and correct the balance first, then the trim, then the flaps, then the ailerons and last adjust the eccentric bolt if needed, which it shouldn't and they should be neutral.
All this is contained in the service manual 100 serious 62 and prior in various places through out the manual and maybe somewhere else I can't remember.
BTY
You might also take a close look the condition of your wings, flaps and ailerons.
I've checked my plane pretty well and can't find a reason for the heavy left wing except maybe this. One wing was repaired at the tip. The last foot of leading edge bottom of aileron outboard hangs lower than the wing. We can't figure why other than the wing was not jigged properly when repaired and we don't know the effect this has on the plane. I'm living with it for now buy just putting more fuel in the right side.
CAUTION - My forum posts may be worth what you paid for them!
Bruce Fenstermacher, Past President, TIC170A
Email: brucefenster at gmail.com
The eccentric dolt in our organization lives in La., and will doubtlessly respond shortly.
(I believe you can put them down as far as you wish in order to achieve the desired result, but I recommend one move the opposing one an equal amount upward to achieve a happy balance. This should result in a minimum amount of deflection of either wing.)
BTW, I'll bet you already knew this, but just as a reminder, ...when you rotate that eccentric bushing make certain to rotate the forward/rear halves in unison or you'll stress the bolt which passes thru them as well as the carry-thru spar where they reside. (The bushings are actually eccentric, ...the bolt is a plain aircraft bolt.)
Interesting article in the October issue of LPM on Engine Mounts. States that sometimes sagging or improperly installed engine mounts, which change the line of thrust, are assumed to be a heavy wing or adverse yaw and is corrected by changes to wing and flap settings.
Well I'll just renew this thread as well. I've pretty much decided to keep my 170 and not build a Bearhawk so I'm going to start looking into correcting some of the long standing problems. My aircraft also has a very heavy left wing. With equal fuel levels in each tank and ball centered, the left wing will drop rather quickly when I take my hands off the yoke to read a chart. The only way I can hold the left wing up is to punch in right rudder which is not pleasant. Looking at the eccentric bushing/bolt group on each wing shows that the trailing edge of the left wing is almost as far down as it can go, and the trailing edge of the right wing is almost as far up as it can go. My mechanic said we could try to drop the left flap down in the slipstream to hold the left wing up, but I find that this is not working, although with 10 degrees of flaps she flies hands-off now....but I don't want to cruise with 10 degrees of flaps What bothers me now, and didn't when I "just had to have this plane" several years ago, is the fact that in 1962 it was flipped in a storm. The outer portion of each wing was rebuilt, and I am afraid the some "Billy Joe Bob" somewhere did not bother to use a jig and introduced an inadvertent twist into one or both wings.
Any advise
I think the only thing that may be done short of replacing one or both wings is to install a trim tab on the left aileron and set it for hands-off flight so that I can safely read my charts while in IFR conditions. From what I see here, there may be more than a few 170s flying around with a heavy left wing. Are there any answers
John, there's no approval for a trim tab to be added to the ailerons. I remember seeing a 170 at a previous convention which the owner was very proud of... no one had the courage to disappoint him by telling him the two tabs (all bent up way out-of-streamline, and exactly cancelling each other out) were illegal.
It's possible your rudder is not streamlined. This can be due to your rudder tab being set incorrectly, or it could be that someone installed their own idea of rudder-return springs, which would impart un-even forward rudder to one of your rudders. (left possibly?) With your tailwheel chains disconnected and your rudder relaxed (give it a swing left/right and let it relax in a no-wind area like a hangar), the rudder should be centered or ever-so-slightly to the right. (And one reason the steering chains are disconected during this check is, ...you guessed it.... the tailwheel can have faulty bearings/kingpin which can cause it to drag in a left-rudder application. I'll bet you know what that can do.)
Your ailerons circuit may also be out of adjustment. Tape a straight edge all the way across the tops of your yokes (yardstick works) so they will be exactly centered and look at your ailerons. They should both meet your flaps at the outboard ends, and the ends of the ailerons should be about 1/2" below your wingtip fairing. The cables should be just taut. (We're just doing a quick-check here.)
Check your horizontal stab and elevators for left/right match-up.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention. An originality nut (mostly) for the right reasons.
Thanks for the tip concerning the CPA. I am in the eastern panhandle of West VA. Do you know of one in this area? Ahaaaa I had not thought of the elevator halves being out of rig. I'll check this today. We have gone over all of the simple stuff in the past year or two. The rudder has been checked and rechecked several times. Tailwheel chains are the standard units and are new. Short of going to a rigging specialist I suppose the elevator halves are the only thing I can check now. I've done all the usual checks....but it will not hurt to do them once again I suppose. I could try to adjust the eccentric bushings just a little more, but my mechanic tried to move the bolts during annual last year and they would not budge. He recommended they be left alone since they are frozen in place....having been last adjusted so many years ago that they are now one with the airframe
First John start putting some breakfree on those frozen bolts.
I have the same problem that your do and have pretty much determined that either the my left wing IS heavier than the right or it was repaired incorrectly.
I first I rerigged my aircraft from the grossly out of rigging that it was adjusted to for a heavy left wing by centering the eccentric bolts and adjusting the rudder. Guest what. The left wing still dropped just as much but the plane went faster.
Since adjusting the eccentric bolts in my case back to adjust for the heavy wing condition had very little or no effect on the heavy wing condition I tryed cheating the adjustment for the flap just a little and then the aileron. I was able to geth the heavy wing to fly a little lighter but it's still not perfect. I generally put more fuel in the right side to compensate.
While fudging the ailerons and flaps are not technically correct the text book proceedure doesn't take into effect a 55 year old slightly bent airplane. Who is to say that the fuselage wing fairing that you ar lineing the flap up with was not repaired/replaced and miss aligned.
Again make every effort to follow the text book then try a slight fudge.
BTW you should not only test a rerigging by flying level but also test it through several stalls to see what effect if any the adjustments have when the wing stalls.
CAUTION - My forum posts may be worth what you paid for them!
Bruce Fenstermacher, Past President, TIC170A
Email: brucefenster at gmail.com
With aft wing attach bolt nut backed off, the wing adjustment bushings (eccentric bushings) must be moved together in the correct direction (one at a time, aprox 1/8 flat) in order to turn. If the last adjustment was incorrectly attempted the assembly might be binding together, a small wiggle on one side in the correct direction should allow the eccentric half to loosen and move. Then find the range of the sweet spot to move them together. The eccentrics do not require any great force to rotate, if there is resistance to movement its due to binding, one half of the eccentric bushing moving in an opposite direction to the other bushing half.
Big G is on the correct track to ensure rudder is correctly rigged, then flaps, then aileron. The wing adjustment should correct the heavy wing (it doesn't take much).
Big J is also correct about the bushings.... It's NOT the bolts that are eccentric....it's the BUSHINGS. (if the bolt does not move, then the bolt is likely corroded within the bushings and/or block (on the fwd bolt.))
The two bushings should be moved simultaneously...not seperately. IF they've been adjusted previously not-in-sync with each other...they may already be bound. Look closely at the flats vs the thick/thin portions of the bushings and see if they are in the same relationship with each other. (And nothing wrong with using a little WD40/LPS-1.)
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention. An originality nut (mostly) for the right reasons.
I'm back on the eccentric bushing trail again, trying to center up the bushings for the CPA rigger before he makes his visit. I have both nuts off, but the bolts refuse to move. I hope the problem is binding between the bushings, and not corrosion, but I do fear the worst here. On the advice of a recent Flypaper article, I'll be having my A&P drill a hole in the top of the cabin over the hat section to run a borescope inspection up there, but I think these spar bolts may be telling me of a big project ahead. If moving the bushings will not free up the bolt, would it be OK to put a 3/8 air ratchet on it and let it run until the corrosion frees up and allows the bolt to turn? I've been soaking the bolts with a "liquid wrench" compound for two days. Once the bolts are free and able to turn...what is to procedure for their replacement? If I remove the bolt, will the wing swing back or drop? Should I follow the bolt during extraction with a drift to maintain the alignment of the attatchment group and avoid wing movment?
I'm thinking you may want to support the wing and then, using a socket or wrench, attempt to turn the bolt within the bushings. If you've soaked it and it still doesn't turn, I think you've got an excellent chance of corrosion in there.
I sure hate the idea of drilling holes in the upper cabin. If you can support the wing and get it disassembled, you can remove the bolt and bushings, and inspect all the way thru without drilling holes.
The vibration idea might be good, just don't overdo it with too much torque. Remember, even if the bushings were misaligned so as to grip the bolt...turning the bolt should also turn the bushings. You just don't want to hurt the hat section by turning bushings that are jammed in it. Can you not turn both bushings simultaneously while supporting the wing?
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention. An originality nut (mostly) for the right reasons.
John I wouldn't do anything drastic until you had a knowledgeable person look at it. Perhaps this might be the rigger since he should know and understand how these eccentrics and the bolts work.
You may have corrosion you might not. I'm betting one eccentric is jammed against the other and the bolt.
CAUTION - My forum posts may be worth what you paid for them!
Bruce Fenstermacher, Past President, TIC170A
Email: brucefenster at gmail.com
I have not tried to turn the bushings yet, but will go out this evening or tomorrow and give it a try before putting an air ratchet to work. I'd wait for the rigger to arrive, but I don't want him to have to sit around while I/we try to free up the bolts/bushings. If I can get everything freely turning, the rigger can come in and do his magic. George, you say when the bolt is removed, there is enough room to get a borescope in to have a look at the interior of the hat section? I too hate to drill holes, but also hate not knowing what the inside of my hat section looks like...especially since my airplane has spent far more time outdoors in years past. I'll station my understanding wife out at the tip of the wing when/if I ever get the bolt free enough for removal, that way she can keep the wing from swinging aft...which is the way I think it will go once the bolt is out. If it drops down as well, my hard head will catch it long enough for me to boost it back up and get a drift in the vacant hole
to give to correct a low left wing condition. Bolt appears to be at max down position on left wing while right wing is somewhere on the high side. Where is the reference on how much to give or take? Anticipated thanks for your help
What bothers me now, and didn't when I "just had to have this plane" several years ago, is the fact that in 1962 it was flipped in a storm. The outer portion of each wing was rebuilt, and I am afraid the some "Billy Joe Bob" somewhere did not bother to use a jig and introduced an inadvertent twist into one or both wings.
I had not thought of the elevator halves being out of rig. I'll check this today. We have gone over all of the simple stuff in the past year or two. The rudder has been checked and rechecked several times. Tailwheel chains are the standard units and are new. Short of going to a rigging specialist I suppose the elevator halves are the only thing I can check now. I've done all the usual checks....but it will not hurt to do them once again I suppose. I could try to adjust the eccentric bushings just a little more, but my mechanic tried to move the bolts during annual last year and they would not budge. He recommended they be left alone since they are frozen in place....having been last adjusted so many years ago that they are now one with the airframe 
