Leaning Left, and that's just not right!

[cmsusllc]

My 53B I bought about a year and a half ago as a flying project has had a left leaning inclanation since I brought her home. I've made a few stabs at correcting the situation without positive outcome. The annual was just completed with an eye for the problem with nothing jumping out.
A little history; The plane has averaged 100 hours per year since new. currently about 5600 hours TTAF. It was groundlooped in 93 and was well repaired- right wing damaged as well as the gear box. During the annual we rerigged the flaps and ailerons to specs, they were very close, no change. Also noted were the excentric adjustments at the rear spars- the left one is full down and the right one is full up.
Today I decided to find the problem once and for all. I test flew it to actually derive some base line information. At 80,100,120 &140 mph trimed out it would roll left hands off about 30 degrees in 5 seconds. The roll rate is the same at any speed although with increased speed it requires increased effort to maintain wings level. I lengthened the left flap control rod first one turn at each end then another turn, flight testing it each time.It seamed to slow the roll rate to about 7 seconds and slightly lessen the control pressure required for straight and level. It appears to increase the cord of the wing a little but does not droop the flap due to the free play in the tracks. And yess I slid over to the RIGHT seat while testing, it still goes left but at an even slower rate and control pressure is even lighter.
Now it was time to get more serious. I dug out of my van levels, straight edges, string, plumb bobs, laser levels, and tape measures. I lifted the tail wheel 30 inches [ air lift motorcycle lift ] leveled the front spar carythrough above the windshield by making slight air pressure adjustments to the tires and verified with the rear spar carythrough [ the headliner is removed ] and the door frames, both top and bottom. I set up a lazer, verified it being parallel with the cabin frame and measured the wing tips three different ways. It showed the right wing tip to be 3/4 to one inch lower than the left wing. I then droped a plumb bob at the front of each wing tip and measured to the tail spring u-bolt, only 1/4 inch difference. Next I plumbed the vertical stab- perfectly plumb. Finally the horizontel stab was checked, one inch lower on the right, verified with a level on the rear spar.
I'm trying to get it thru my thick right leaning skull if the horizontal stab can be the problem. Ideas would be appriciated.
Thanks, Scott

[canav8]

Hi Scott, unfortunately you are describing two different problems. The first problem I think you are addressing is a leaning situation while parked. That is adjusted through the landing gear. The next situation is an inflight problem and that is adjusted in the wing,aileron,flap rigging. Test flights require the test of how much yaw is occuring while you describe the roll rate. What is the heading doing? Where is the rudder? and the rudder tab doing? Yaw should be corrected before roll. V/R Doug

[Bruce Fenstermacher]

Hi Scott,

When first reading your post like Doug I though you were talking about leaning while on the ground yet all you describe would be measurements and corrections for leaning in the air so I'll assume that is your problem. You might want to confirm exactly what your talking about here.

As for leaning or a heavy wing as I call it, I have the exact same problem as you do. Sounds like yours might be a bit worse but never the less a frustrating problem when obvious solutions aren't found.

First as Doug has pointed out you want to confirm and adjust the yaw first before roll and this is done with the rudder. Actually the first step is check that your yaw indicator is level or ball centered. Level the aircraft. Check to see the gage is centered and if not adjust it so it is. Then fly and adjust the rudder trim tab.

A word about leveling. Your have laser levels. I'd us them to level the aircraft. With a bubble level if you are just a hair of center that difference out at the wing tip will be much greater. Cessna's point(s) for leveling are the upper door sill for both for and aft and lateral leveling. Of course you would thing the carry through spars could be used for lateral leveling but that is not what is called for.

In my case I think my heavy wing condition is not because the wing is physically heavier (though it could be) but that there are several things repaired slightly out of true on the left wing which causes more drag on that wing. The outer last foot of my aileron on the bottom hangs down lower then the bottom wing skin by about 1/2 inch and the outer section of the flap from the outer hinge to the end hangs lower than the bottom wing skin again by at least 1/2 inch. The increased drag on the left wing causes the plane to yaw left and the left wing to droop or feel heavy. I've already got a lot of rudder trim to counter that yaw and need more. Much more than most other 170s I've seen. I haven't put it in yet.

Since the yaw is not corrected completely to compensate someone adjusted the eccentric bolts to their limits increasing the lift of the left wing and reducing the right wing which helps lift the wing but does not correct the yaw problem. By the way all this asymmetric drag and incorrect rigging to compensate adds additional drag and as a result my plane is also one of the slower 170s I've seen.

So look for things that would cause drag on one side and not the other as well as measuring the airframe. It makes a difference.

BTW the only correct way to trim the wings according to Cessna is with the eccentric bolts. having said that I have tried as you have adjusting a flap or aileron. On the flaps I've found it not very possible to get much asymmetric adjustment without one flap hitting a stop without the other hitting the same stop and that is either in the up or down position.

Specially since you know your one wing was repaired you might wan to use your laser level to measure and compare the twist (washout) between wings from the strut attach point out. This might tell some of your story.

Good luck

[Metal Master]

During the annual we rerigged the flaps and ailerons to specs, they were very close, no change. Also noted were the excentric adjustments at the rear spars- the left one is full down and the right one is full up.

I rebuilt my left wing after I purchased the airplane on E bay as a ground looped project. Before flying the airplane I checked the wing twist and installed angle of incidence of the wings on the aircraft with my laser level. I posted the description of this work elsewhere on this forum at the time. If anything the eccentric condition you noted should cause the airplane to roll right not left. The question I would have would be whether you have a wing heavy condition (heavy in flight not weight) *** If that condition could be compensated for by rudder and if so is the airplane then skidding while the airplane is now being held wings level without aileron input. Before making this flight it is a must important to know that your Slip skid ball is leveled to the aircraft so that you can accurately tell if you are skidding or slipping in flight. If every thing is repaired correctly the airplane should be able to be rigged with out the flaps or ailerons being adjusted from their full up or correct neutral position as appropriate. I live in Seattle and can show you how to do this some time if you contact me by private PM.

*** Making adjustments to the flight rigging without first making the following the determination of wing heavy and or slipping and our skidding flight first causes one to really chase the their tail. And yes the stabilizer not being level meaning the whole stabilizer and or rear fuselage is twisted could cause this sort of problem. So can rudder neutral relative to flight and the position of the rudder relative to the tail wheel and rudder pedals cause flight trim troubles?

My aiplane flys wings level hands off in cruise flight. The 172 I just re-rigged for a 1956 172 owner who had a similar problem to yours now flys wings level hands off. The aircraft that were correctly rebuilt that I have rigged fy right. Others which were not don't.

Regards,

Jim

[Bruce Fenstermacher]

Jim,

You are right that an otherwise normal aircraft with the eccentrics adjusted as Scott described "Also noted were the ecentric adjustments at the rear spars- the left one is full down and the right one is full up.", would make the airplane turn right. But my aircraft, and apparently Scott's, still turn left. Even with all this adjustment to make the airplane turn right.

[Metal Master]

Jim,

You are right that an otherwise normal aircraft with the eccentrics adjusted as Scott described "Also noted were the ecentric adjustments at the rear spars- the left one is full down and the right one is full up.", would make the airplane turn right. But my aircraft, and apparently Scott's, still turn left. Even with all this adjustment to make the airplane turn right.

Roll right not turn right. And I say again If every thing is repaired correctly the airplane should be able to be rigged with out the flaps or ailerons being adjusted from their full up or correct neutral position as appropriate. The total change if I recall from the last time I drew the eccentric change out full scale = total change from full up on one eccentric and full down on the other is about one degree difference. I have seen airplanes built with wings from different jigs that could not be adjusted to fly right. One repairer put a curve in the leading edge that you could see when sighting down the leading edge of one wing nothing could make this airplane fi right the wing leading edge had to be re done.

Draw your own conclusion an airplane is either buitl / repaired right or the airplane is missed rigged.

Jim

[Bruce Fenstermacher]

OK Jim I should have said roll instead of turn. Cessna says as you do that you shouldn't have to adjust the aileron or flaps to trim an aircraft, while I haven't been able to do it to mine, I have no reason to disagree with you. I also agree that if you can't there is probably other issues such as I pointed out my airplane has.

[170C]

Wished I had a good suggestion to remedy the problem, but if my ole bird would fly 140 mph in calm air I might just live with a heavy left wing Bet somebody will come up with a solution though, but it may slow you down to the usual 115 or so mph. Good luck

[Bruce Fenstermacher]

Wished I had a good suggestion to remedy the problem, but if my ole bird would fly 140 mph in calm air I might just live with a heavy left wing

Those little details such as a 140 mph pass with a 170 don't easily get past guys with square tails do they.

[cmsusllc]

I'll try again. I posted a clairification yasterday but it did not show up.
My 170B flys left wing heavy with a roll rate of about 30 degrees in 5 seconds, reguardless of speed. Ball is centered, feet on the floor when hands are removed.
Wings are square with fusalage. At worst the right wing tip is one inch lower than the left with cabin properly leveled.
Vertical stab is plumb.
Horizontal stab is one inch lower on the right, definately out of square. could this be the problem?
Thanks for everyones help, Scott

PS. 140 mph indicated requires a 300 fpm decent. 130 indicated in level flight at 2500 msl- 25 squared.

[wingnut]

Scott,
I doubt the stab would be causing the significant roll problem you are having. In fact, I doubt it would cause any unusual flight characteristics, if I'm uderstanding you correctly.
The fact that the wings have been repaired, and eccentrics already adjusted to their maximum directions to attempt correcting the problem suggest to me that you have improper washout on one or both wings.
From what I'm understanding in your post, you have performed a symmetry check, but have not checked wing twist (washout). Cessna specs allow plus/minus 1/2 degree (meaning you could have a total of one degree difference between left and right wings), and this is the absolute maximum difference that the eccentrics can be adjusted to prevent a roll problem.
If your wings are outside of this total one degree difference ther is no way to remedy. Lowering a flap generally does not produce noticeable results, except more yaw. Aileron adjustment has absolutely NO effect; they will always find a "neutral" faired position regardless of yoke position.
I have seen roll induced by an aileron trim issue. Yeah, I know the 170's do not have aileron trim. I'm talking about the "sweep-up" at the outboard end of the ailerons. If one has more than the other, it acts as a trim tab. This problem can be identified by the yoke continuing to turn to the left, assuming the left wing drops (watch your ailerons in flight). If after letting go of the yoke, the ailerons appear faired with the wings (evenly) and find their neutral spot here, and the plane continues to roll, then it's wings. If your holding yoke pressure to maintain level flight, disregard yoke position; where are the ailerons in relation to wings? Is the left one slightly down, and right slightly up? If so, it's wings.
One wing tip being one inch lower than the other would not cause a roll problem, but would suggest the station 100 spar splice was not properly aligned during repair, which in itself would suggest possible washout issues.
You say both the right wing, and right side of hor stab are one inch lower than their opposites with the fuselage level. They are at least "off" in the same direction, so I'm inclined to believe the fuselage is right, or so close to not cause any problems.
I don't agree with the published 170 symmetry check instructions. It calls for measuring from each wing tip to a point on the cowl, suggesting the measuements should be the same. But, when you adjust the eccentrics, you are also moving the wing tips fore and aft, as well as trailing edge up and down. So, it would be a normal condition for tips to be a different distance from a common centerline at the nose if your eccentrics are not neutral.
Some people have installed fixed trim tabs to the ailerons to avoid constantly fighting roll. This is not approved, and is just a band-aid for bigger problems.
Not to be blunt, but you'll need to learn to live with it, or have the wings looked at and possibly re-repaired.

[Bruce Fenstermacher]

Just curious. Measure the strut length side to side as best you can to see if maybe an A model strut was used on the right wing as part of the repair. A model struts are shorter. Wouldn't explain the right horizontal stab being lower.

When you say the right wing tip is lower is that just at one point compared to the same point on the other side. Or do you think the wing tip has the same overall pitch on the right as the left. What I'm getting at is was the wing rebuilt with the same and correct washout as the left wing. Again this would not explain the stab being lower on the same side.

As you have a wing in the right that is lower and a stab on the right being lower I'd triple check the lateral leveling of the aircraft. I'm sure you already have but that is still what I'd do.

As for the horizontal stab being lower on the right side and if that would cause a left roll I'd say not. If anything I'd think it would cause a right roll. Remember the elevator is pushing down all the time. If it is not pushing straight down but to one side because it is not level with the wings then it would impart a sideways push. In this case pushing the tail down and to the left and the nose of the aircraft to the right and up. This would normally just cause the aircraft to slip and just be out of trim but because of dihedral and the increase speed of the left wing the left wing will rise and impart a right roll. That is the way I see it anyway. Any other armchair aerodynamics engineers care to comment?

[johneeb]

Bruce,
That armchair is getting a workout today!

[Bruce Fenstermacher]

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?

[wingnut]

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.