Advice For Leveling Plane To Set Slip/Skid Indicator

Discussion in 'Maintenance Bay' started by Sinistar, Oct 21, 2019.

  1. Sinistar

    Sinistar Pattern Altitude

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    TLDR Version:

    How you do check level on a high wing Cessna? Where to place the level?


    Our last annual was pretty interesting. Did a few simple updates instead of just fixing squawks. One fix was that the plane was rolling left in cruise making it hard to fly hands free. He (A&P)termed it flying "pilot side heavy" or "pilot wing heavy"...never heard that before. I was like "Do you just adjust a aileron cable or something?". He smiles "I will tilt the wing a bit more :)". Okay...never knew that either. Pretty interesting how the design supports this and actually its not that much effort ($$$). He also assured me its never been adjusted since it left the factory. But the plane always had a wing leveler (until it died last winter) so maybe the other owners never cared to get it rigged properly. Even funnier...took me about 100hrs of flying to finally do something about it.

    So this is for a Cessna 182P, probably applies to many other planes as well.

    So for the pilot wing heavy he took a guess and angled it slightly more. Now, once I reach cruise I rudder trim until the slip/skid ball is dead center. I re-trim the elevator, etc. It is still just slightly pilot wing heavy. If I use a bit more rudder trim than needed (ball is now slightly left of center) it seems even better (very, very slow roll rate). But am I now uncoordinated slightly in a way that stops the left roll rate with hands off?

    So my (A&P) gave me some homework LOL! Partly because he's busy and partly because he's letting me learn something I think :) He asked me to get the slip/skid indicator properly leveled on the ground first so we can be sure the ball being centered represents no slip/skid in the air. For all we know he may have moved the wing a bit too far if the ball is off. He told me how to unlock/rotate/lock the instrument. But we didn't have much time to chat about getting the plane level to set this up. Its a new Turn Coordinator and the avionics shop that installed it (last winter) probably didn't level it properly as just looking in or sitting in the plane it doesn't look quite centered.

    So does anyone have any advice on how/where to determine the plane is leveled first before adjusting this instrument? On the high wing Cessna's can a level be used on the underside of the wing, right above the cabin, etc.? Maybe I just measure each wingtip to ground? The slab in our hangar seems level so I think I can start there or I can move and do this outside if needed.

    Also, once in cruise and all trimmed out. Can airspeed (or ground speed) be used to determine if the ball is truly centered and there is no slip or skid occurring. I didn't get much time yesterday to experiment but it seemed if I used pretty excessive ruder trim and got into a slip/skid the airspeed would drop. Maybe I was just seeing what I expected.
     
  2. Skip Miller

    Skip Miller Final Approach

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    Somewhere in the plane’s maintenance manual, it will tell you the leveling points. In Piper Cherokees, the door sills are the leveling points.

    Cessnas? Sorry, I don’t know.

    -Skip
     
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  3. Bell206

    Bell206 Pattern Altitude

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    The level location should be in your POH around section 6 or 7(?). If I recall on a later model 182 its somewhere on top of the tailcone for longitudinal leveling. For lateral leveling most 100 series Cessnas usually use a level across the door sills.
     
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  4. Timbeck2

    Timbeck2 Final Approach

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    Find out from the maintenance manual or the mechanic exactly where the leveling points are on your aircraft. Then using jacks under the wings, tail weight or even letting air out of the tires, or a combination of all, get it level in both axis. Then look at the turn and bank and clock it accordingly.
     
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  5. Timbeck2

    Timbeck2 Final Approach

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    In my Cherokee 140, the leveling points are the spar underneath the rear seat and the two screws just under the pilot's side window.
     
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  6. Bell206

    Bell206 Pattern Altitude

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    FYI: Most older 100 series Cessna leveling/weighing procedures are in the POH.

    upload_2019-10-21_15-32-0.png
    upload_2019-10-21_15-31-35.png
     
    Last edited: Oct 21, 2019
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  7. Salty

    Salty En-Route PoA Supporter

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    I would think pitch level wouldn't really matter much. It's roll level that you care about. I'd put it on a flat surface, use a 4 foot level on the ground to find a level area, make sure the tires have equal pressure and the ground is level, then you just center the ball. No?
     
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  8. Tantalum

    Tantalum En-Route

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    Sounds too easy.. if planes are involved the solution must be far more pedantic and involve pulleys, pistons, weights, clocks, sundials, and several thousand dollars
     
  9. Salty

    Salty En-Route PoA Supporter

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    Obviously you need an A&P to do this and put an entry in the logs. ;)
     
  10. Sinistar

    Sinistar Pattern Altitude

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    Yes, in my case I am only trying to get the roll level (slip/skid ball) centered properly on the ground. So I wasn't going to do anything with pitch. The door sills make a lot of sense but I will check the POH. I didn't even think to look there are is doesn't seem like something you would put in there.

    I guess there could be some small quirk of one tire not being the exact same height as the other at the same pressure but yes, this should probably work. Actually if its not quite level I was just going to roll one rear wheel up on a thin board - absolutely no plans to jack or lift. Should only take 5 minutes once I know where to check for level.
     
  11. PaulS

    PaulS Final Approach

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    Sounds like you need a mechanic and sign off to get this done.
     
  12. Sinistar

    Sinistar Pattern Altitude

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    Man I hope you are kidding. Its my A&P who told me to do it and get back to him once I level the TC and test fly it again. I'll let him adjust the wing :)
     
  13. PaulS

    PaulS Final Approach

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    Nope, not kidding, but sounds like you are being supervised by an A and P, hopefully he'll sign it off for you.
     
  14. mwagg737

    mwagg737 Pre-takeoff checklist

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    If you have a heavy wing, do not, I repeat, do not try to fix it by moving the ailerons.
    Center your ball like you want to with your leveling, but then go deep stall the airplane. Which way does it roll if it rolls. All too often, your problem can be found in the rudder rigging. If everything is rigged properly, your next step is to adjust the wing incidence using the eccentric bolts. I believe all single engine Cessnas have those.
    Something else you can do. hold the wings level with the ailerons and leave your feet on the floor. Does the airplane want to flat turn?


    Sent from my Pixel 2 XL using Tapatalk
     
  15. Tantalum

    Tantalum En-Route

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    ...and then:
    ah hahahahaha


    ..and we wonder why GA is dying. Really?! A signoff is needed to center the ball in the cockpit?
     
  16. Tantalum

    Tantalum En-Route

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    Surely p factor is a non agnostic element here
     
  17. PaulS

    PaulS Final Approach

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    Is it listed in the allowable owner maintenance? I doubt it, so it should have a sign off.
     
  18. Tantalum

    Tantalum En-Route

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    I'm not saying your wrong.. it's just incredible. I agree that adjusting wing incidence is a no no for an owner.. but I would think if you can reasonably determine the plane is wings level you'd be allowed to calibrate the ball yourself
     
  19. Bell206

    Bell206 Pattern Altitude

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    FWIW: Unfortunately, it's not what a person would "think" is reasonable but what is stated in the FARs. If you can fit calibrating an inclinometer into the definition of preventative mx I would be the 1st to back you up. In this case the OP is working with his mechanic to make that happen and work within the rules--which is how the system was designed to do in the 1st place.
     
  20. Tantalum

    Tantalum En-Route

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    True.. still, I thought salty's idea made sense
     
  21. Salty

    Salty En-Route PoA Supporter

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    If your mechanic agrees, there’s no issue. I doubt many would even charge you for the sign off, if you did all the work. I don’t have a problem with this system.
     
  22. PaulS

    PaulS Final Approach

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    Yes, I get it.

    My brother used to work at a bearing company back in the 80's as an engineer. This was when ultralights were getting popular, some had pillow block bearings to drive the props. They would eventually fail and need to be replaced, but there were very specific parts for this application as they had a lot of forces on them and they typically were spinning at more than 3,000 rpm. As you can probably guess, the proper part was expensive, but there were also cheap versions, meant for conveyor belts with low relative loads and only meant to spin at maybe 100 rpm. These guys would buy the $20 conveyor pillow block instead of the $200 proper pillow blocks and bolt them on. When the inevitable started happening, the grieving widows began suing the bearing company.

    While most pilots would probably be pretty good at doing this stuff, the "muttonheads" ruin it for us all.
     
  23. Bell206

    Bell206 Pattern Altitude

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    And it does. But considering the earth is round and everything is built to drain/shed water there are very few true flat areas. With a truly level aircraft you can nail it the 1st time, every time.
    Agree. Unless I got thirsty waiting on them to finish which would cost them a 6 pack to sign it off.;)
     
  24. Tantalum

    Tantalum En-Route

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    Indeed! We have to cater to the lowest common denominator!

    Wait, you don't subscribe to the flat disc Antarctica/Illuminati theory? They're not dumping enough chemtrails over your house man

    In all seriousness.. If you flew fast enough around the earth wouldn't you see your gyro nose over? I was always curious how they handled that in the space shuttle during reentry.. assuming X15, XB71, SR71 Etc, while fast, we're not fast enough to experience an issue
     
  25. JAWS

    JAWS Line Up and Wait

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    From 182 TCDS

    Data Pertinent to Model Items I through XIIDatum Front face of firewall

    Leveling Means Upper door sill. Top surface centerline of tailcone (S/N 18253599 through 18265965) Jig located nutplates and screws on left of tailcone (S/N 18263479, 18265966 through 18268586) (S/N R18200001 through 18202041)
     
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  26. flyingron

    flyingron Touchdown! Greaser!

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    Many of the aircraft use the seat rails for left-to-right leveling. However, the TCDS and/or maintenance manual should explain all this.
     
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  27. thomasdr72

    thomasdr72 Pre-takeoff checklist

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    So, I just did some investigation on our C210B (which is very much like a 182 in many respects) and knowing about the concentric bushings-that was my first go-to when troubleshooting our pilot-wing heavy discrepancy. In cruise flight, when rudder trim is set to prevent the roll tendency the ball is about half a ball-width left of center. Additionally, the bird is about 20mph slow at the top end of cruise, and of course the faster we go--the worse the rolling tendency seems to be...

    Consulting the interwebs, I came across these two articles:

    https://cessnaowner.org/the-right-way-to-rig-a-crooked-flying-plane/

    and

    https://cessnaowner.org/what-to-do-if-your-cessna-airplane-is-slow/

    These articles have convinced me to dig in and double-check the rigging before adjusting the wing incidence. I can report that I went out today and re-rigged the flaps according to the book, and they were significantly out of rig, with the right flap being a few mm extended when the flaps were in the retracted position. So, if you think of that delta (which wasn't really noticeable when the flaps were retracted) the right wing would (should?) have been producing a tad bit more lift than the left...

    A follow-up test flight should confirm, but I feel good about the logic!

    Additionally, now I notice that the ailerons are now slightly out of rig as well (next up on the tweaking list!).

    Why did I post this? Well, I must admit that I was very hesitant to mess with the rigging (and many of my A&P friends would feel the same) however, it took about an hour to rig the flaps, and it promises to help me fix the issue.

    Cheers!
     
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  28. Bell206

    Bell206 Pattern Altitude

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    Curious. Why would you and your friends "hesitate" to check and/or adjust the rigging? Anytime I ran across a control/flying issue, whether airplanes or helicopters, after a quick visual check the next step usually was to verify the rigging.
     
  29. thomasdr72

    thomasdr72 Pre-takeoff checklist

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    It was different when I was working on helicopters too, and there was a fancy set of rigging pins to precisely check the rigging of things with... It seems a bit different when the rigging check is to eyeball things and see if they "look" centered in a particular slot, or does the trailing edge of the flap "look" aligned with the wing root fillet, etc...

    When I did the annual last month, it "looked" fine. When I disassembled the system to re-rig it, then I figured out that it was off...

    YMMV...
     
  30. bluerooster

    bluerooster Pattern Altitude

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    Wrong. There are two screw heads on the left outside for longitudinal, and the main spar carry through for lateral. I know nothing of Cessna.
     
  31. FastEddieB

    FastEddieB Final Approach

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    Mot sure what you’re getting at.

    I agree adjusting the linkage to the ailerons should be left to A&P’s.

    But any time one of my planes had a slightly “heavy wing”, it was pretty easily corrected via aileron trim.

    Or did you mean something else?
     
  32. mwagg737

    mwagg737 Pre-takeoff checklist

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    Aileron trim is one thing. You are basically holding the yoke against the heavy wing. Both alierons are at work.
    I am referring to trying to drop an down to compensate for the roll. It won't work and will result in more drag with the same problem.
    The alierons should be even with the flaps/edge of wing tips and the yoke centered. If there is a rolling tendency it's usually a rudder misrig problem, a slightly drooping flap or wing incidence issue.
    When rigging, it's best to start at factory settings and tweek from there... Especially in an old airplane that has probably been rigged incorrectly over the years.
    As a point of reference. I gained 9KT in my Mooney after taking the time to rerig the plane.

    Sent from my Pixel 2 XL using Tapatalk
     
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  33. FastEddieB

    FastEddieB Final Approach

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    Got it.

    A bit off topic, but...

    When I took delivery of my Sky Arrow, the ailerons had a disconcerting oscillatory behavior that the plane I had demo’d hadn’t had. A spot of turbulence, or even quickly moving the side stick, and they would wag back and forth a few times before settling down. Unacceptable.

    I mentioned this to the importer and he proceeded to adjust the ailerons so they were both ever-so-slightly reflexed down in level flight, and that fixed the issue and it remains that way 12 years and 550 hours later. I guess the slight aerodynamic load provides a needed damping effect. I’ve also wondered if I reflexed them both up slightly instead of down if I might pick up a knot or two, but I know enough not to experiment with that sort of thing.
     
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  34. Bell206

    Bell206 Pattern Altitude

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    Don't quite follow your answer. Are you saying if your aircraft had a control/flying issue you would only visually confirm the control rigging vs performing a rigging check? Is that the "hesitation" you mention? Most rigging procedures I'm familar with require checking degrees of control travel, cable tensions, etc. in addition to using your eyeballs.
     
  35. thomasdr72

    thomasdr72 Pre-takeoff checklist

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    Lol, what I learned is that I shouldn't have hesitated a bit... On a 100- or 200-series Cessna, most of the rigging check is visual...
     
  36. Bell206

    Bell206 Pattern Altitude

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    Really. It's been a while but do you have a reference for that statement?
     
    Last edited: Oct 22, 2019
  37. Sinistar

    Sinistar Pattern Altitude

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    Short follow up regarding leveling. Our floor is pretty level. So I measured wing tips to ground, level at the upper door frame and level at the seat rails and all were quite close. So the seat rails are the easiest to grab level from and accurate enough for this exercise.
     
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  38. luvflyin

    luvflyin Final Approach

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    On the wing tips to ground measurements, did you check the ground for level and flatness first? And leveling across the seat rails, did you make sure you had a good ‘bubble.’ Was it an accurate level? Not all are. The way to check it is find a flat surface, doesn’t need to be level, just flat. Put the level on it and look at the bubble. It doesn’t have to be exactly between the lines, just note where it is. Now spin the level 180 degrees and put it down in the exact same spot. If looks exactly the same, you have a good bubble. You can also shim one end of it until it is exactly level. Dimes, pennies and nickels work for this, get it ‘level.’ Now spin it 180 degrees, put it down on the coins or whatever you used exactly like it was. If it’s not still reading exactly level, you have a bad bubble.
     
  39. champ driver

    champ driver Line Up and Wait

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    Do this leveling inside a closed hangar, not outside, winds can effect the leveling.
    Find a level place on the plane like the left and right seat rails, both window sills side to side, or the top of the cabin on the wing center section. If you do this and get it level, it doesn't matter if the ground/floor is level or not.
    Ignore that diagram posted earlier, that's for fore and aft leveling for weight and balance only.
    If you level the plane and then get in the seat to adjust the instrument you'll throw the level all off.
     
  40. Sinistar

    Sinistar Pattern Altitude

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    Yes, I did this indoors. There aren't many places outside the hangar that I would even try it since everything is slightly sloped for drainage. I did it all from standing outside...BTW probably not easy on a single door low plane?

    Good point on verifying level first. I have had it about 20yrs so one would think I would have noticed it being out of level but who knows. Also, if it were off just a bit I don't think a slip/skip indicator is quite that accurate.

    The bottom line is that the A&P's wing adjustment, after flying hands off with elevator and rudder trimmed still results in the pilot wing being slightly heavy. That is with the slip/skid indicator leveled. So he went the right way but about 10% short. My wife just flew it solo as well and same thing so it isn't just my far arse! At least it went from starting to roll left almost immediately after taking the hands off to gently rolling left and about 1/10 of the roll rate.