The International Cessna 170 Association

I have 1953 170B. I’ve noticed that when parked on level ground one wing is lower. In fact there is a 6 inch difference at the wing tips from ground to top of tip between left and right wings Aircraft cabin is level . Aircraft taxis straight and is mostly in trim in flight.
Any ideas?
Dan Waters
Blue Mountain Airpark, GA

Reminds me of the nickname my CFI gave me when I was working on my private certificate -- Won Wing Lo.

If the ground is level and the aircraft cabin is level laterally, the only thing I can think of is that one of your struts has been replaced with the incorrect part. What do you measure the dihedral to be on each wing? I have no idea if a C-170A strut will physically fit on a C-170B but if that's what you have then the dihedral should be 0º on one wing and 2.5º on the other. But if that were the case, my rough estimate is that there should be 8.4" of difference at the wingtip (assuming the wing measures 16' long). Another way to look at it is that the 6" of difference at the tip amounts to 1.8º.

The landing gear can be shimmed to correct this. I’m sure others can provide particulars, but standard AN960 washers can be added/subtracted to the landing gear attach bolts in the fuselage. If no one here answers, call Mountain Airframe in Mena, Arkansas and ask them; they corrected mine that way.

As said, check the lateral level of the plane first. Once the seat rails are level, then you can measure the wings. A water level works best so you don’t have to worry about an uneven floor. An A model strut is possible, however unlikely. I’m not sure what gear you have (early 170, ladylegs, or c-180), but you could possibly have a bent gear leg. Shimming can be done in the gearbox, however I believe there is a limit of 3 washers max that can be installed below the gear, which will only give 3 or 4 inches at the wingtip. This can involve machining though if a p-pork kit is installed and room for shims wasn’t left.

The original gear are “supposed” to be symmetrical, however swapping the early gear on my A model (left to right) fixed my low wing problem. The gear were straight on the floor and all angles matched, so I still haven’t figured that one out yet…..

The early gear can be swapped left/right…but after 170B, serial 25612, the so called “lady legs” became the standard and they are not interchangeable…they are “handed”, different PNs.
The B-model used longer struts which imparted dihedral (almost 3-degrees), so if an A-model strut were installed on one side it would remove the dihedral from that side.

Miles is correct, AM960 washers placed beneath the inside end of the landing gear leg can be used to level the aircraft. The wingtips should be level within 3”. The Cessna 100 Series Service Manual, 1962 and Prior, Para/Sec 5-6 explains:
Item 34 in the following illustration is the AN960 washer or shim:

I assumed when Dan said that the "aircraft cabin is level" he meant level laterally rather than longitudinally. If that is true, adjusting the shims at the inboard end of the gear legs might level the wings, but at the expensive of having the fuselage out of level. It is not getting to the root of the problem. The shims at the inboard end of the gear are to correct for lack of symmetry between the left and right gear legs.

True…If the cabin is not laterally parallel with the wing-attach-points and spar carry-throughs…. the problem will not be corrected by adjusting the gear-legs. But the airplane is significantly damaged if a straight-edge placed across the seat-rails are not parallel to the spar carry-throughs…. I doubt that is the case.

In 99% of cases, the cabin will not be level if sitting on warped/sprung landing gear legs. (It’s not necessary to “level” the cabin floor with the hangar floor to rig the airplane. In fact, it is common that hangar floors are neither level nor true. Many are sloped to provide drainage.

Just be certain wherever the airplane is located within the hangar that the floor does not change slope anywhere beneath the airplane…THEN measure the distance from floor to wingtips. (Also tire pressures, wt/bal of the aircraft, etc should be determined not to be unfairly influential)

Danwaters wrote:I have 1953 170B. I’ve noticed that when parked on level ground one wing is lower. In fact there is a 6 inch difference at the wing tips from ground to top of tip between left and right wings Aircraft cabin is level . Aircraft taxis straight and is mostly in trim in flight.
Any ideas?
Dan Waters
Blue Mountain Airpark, GA

Pics please, level ground, tire inflation normal and straight on view would help this post

If your plane is sitting on that relatively flat floor GAHorn is talking about and the seat rails are parallel with the floor under the belly of the plane under the seat rails, then the wing tips can be measured from the floor to tip to get a pretty good swag at whether one wing tip is higher than the other.

As previously discussed, the floor level is most important. I spent a day chasing my tail trying to sort out a wing level issue. I “assumed” the floor was level from wing tip to wing tip. [looked good] The concrete floor was divided into 8 pads. Yes there a gap of about 1/2 in between slabs but appeared level. Aircraft was placed into flying position and seat rails were level laterally and for and aft. I tried to shim the left hand leg at the single attach point and had excessive sims down at the axle attach point . The right hand side wheel alignment was spot on. But the left was totally out . It was totally frustrating so a long lunch was had. Back to measuring and everything had changed dramatically . The right hand side was now perfect and the left hand side was totally out and wheel alignment had swapped across. and the L/h wing was about 5 ins too low. No body had been near the aircraft . I plum bobbed 2 lines from a point mid way on each spring leg where they enter the fuselage . The distance was about 1/4 in difference . Maybe the aircraft should be a max weight. Water drums were placed in the aircraft . Wheel alignment did change . But still I did have a low wing. Maybe I had a bent wing?? Then the penny dropped .DUH.. originally when I was measuring the alignment of each wheel I was facing towards the prop. Then when after the long lunch I was entering to climb under the fuselage from the prop side facing the tail of the aircraft . I was getting my L/H side mixed up with my R/H side . My spirt level was sitting on the concrete floor under the aircraft and then I noticed the bubble this concrete floor is way out. Time to go home .

The bent wing/wrong strut stuff should be easy to eliminate. The wing should be level when the aircraft floor is level.

Don't count on your hangar floor as a reference plane. It's not flat and it's not level. Wasn't meant to be. If it is you paid too much.

A 3' carpenters level works on the seat rails. Let some air out of the high side tire to level the floor. (laterally) Use a water level as your reference for the wingtips. If the floor of the airplane is level and the wings are level, then your wing-low problem is in the landing gear.

Water levels are awesome tools. Invented by the Egyptians a long time ago. I found works best with 3/8 vinyl tube. (50' for $17 on amazon) 1/8" ID doesn't work well. Works with plain water but best with cheap vodka. Lower surface tension, higher viscosity, never gets the funk. Add some food coloring if you want to get fancy.
Or get a self leveling laser level for $50-$100 on amazon and never mess with a water level again.

cheers,
Pete

I have the same/similar issue. I have not performed precise measurements but when on a flat ramp or hangar surface the ball on the turn coordinator is off to the left. I am going on the working assumption that the instrument panel, turn coordinator, and cabin are properly aligned with each other. Looking from head on the left wing appears slightly lower than the right. A rough measurement shows the right wing tip 5" higher than the left which is a lot more than I anticipated. I have been assuming this is a gear leg issue that could be somewhat mitigated with the shims, but not 5" worth.

Re-reading this thread brought up the point of which gear legs I have for serial number 26181 1954 B. See photo below, they are not lady legs. Nothing in logbooks or 337s regarding P Ponk. Are these the older gear legs?

Thanks,

Bob

And while I am at it, does the P Ponk conversion include different gear legs or just beef up the gear box? Can I visually tell if this has been incorporated?

Thanks

Pponk is only a reinforcement of the leg attachment. It’s a machined block that clamps over the gear leg end and hold down bolt head.

Yes, you can tell if your plane has the Pponk kit. As noted, it is just a reinforcing machined block that goes over the inside mount of your gear leg. You can see the block by removing the inspection plate on the floor of your cabin and looking at the gear mounts.

Go to the Pponk website and you can see pics and drawings of the kit.