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Thread: 22/20 Landing Gear Alignment

  1. #1
    Join Date
    Nov 2005
    Location
    Narvon, PA
    Posts
    4

    Default 22/20 Landing Gear Alignment

    I am rebuilding my PA-22 and changing the landing gear per the Univair tail wheel STC. I plan to build a fixture to control gear alignment and squareness with the fuselage to prevent any crab tendency or abnormal squirrely control. Are there specifications or recommendations on the amount of toe-in (degrees) to build in and if it should be measured with the fuselage leveled or with the tail wheel on the ground? The STC instructions only say to be sure the dimension between the new front fittings is not greater than the dimension between the rear fittings (old PA-22 front fittings).

  2. #2
    Join Date
    Aug 2015
    Location
    Port Orange
    Posts
    6

    Default

    I am in process of restoring PA22/20. We just aligned the gear to be straight with wheel alignment (no toe in or toe out) even though I think I ended up with maybe 1/2 degree of toe out each side. One of the SWPC tech advisors put me onto a rigging CD in the SWPC store. It has great explanation and photos of how it's done. I am fortunate that my friend (also an A&P like myself) has 40 plus years experience building Pitts Specials and aligning gear in the same manner. We had to level the fuselage and did so first. Then plum bobs dropped from center firewall and center tail post area to snap a center line on hangar floor. Then a 90 degree mark snapped with chalk line about center line on L&R Axles. This mark made using a homemade large compass and swinging marks (like you use to do in geometry class high school). 36 inch angle aluminum (straight edge) was attached to wheel discs, 16 inch measurement made from center axle both fore and aft. Using a T square down from angle aluminum at the 16 inch marks measurements from the floor point to the fuselage center line was taken fore and aft, both left and right gear. Comparing the measurements you can determine your toe in or toe out. Now for the tough stuff. You have to heat the axles properly with a rosebud torch (after removing wheels) and using a heavy duty bar placed in the axle, pull the axle fore or aft depending on where you want to end up. This process is repeated as many times until both fore & aft measurements are the same, but caution: let the axles cool naturally and completely between each heating before putting wheels back on or weight on wheels. After each change the airframe must be checked for level and plum bobs back on center line before taking measurement. Took us about two days to complete but very happy with results.

  3. #3
    Join Date
    Jun 2014
    Location
    Merritt Island
    Posts
    23

    Default

    Did the same as above but used a laser to project the lines worked out to be about the same. Towed the fuselage to my house for painting with the tail wheel tied in the back of a pick up truck and mains on the road. Got up to approximately 25 mph and the fuselage tracked straight as a arrow. Gona attempt a little more speed on return trip and see how it does.

  4. #4
    Join Date
    Apr 2019
    Location
    Orlando, Florida
    Posts
    22

    Default

    I made a tool to align gear. Angle iron about 10 inches long. Welded to the center at 90 degrees...... a small tube to insert
    a laser. Clamp to axle. Go forward 30 or 40 feet. Mark laser position. Unclamp laser and flip over the other way on same axle.
    Mark again. The projected angle from the axle is exactly inbrtween the two marks. Then do the other side the same.
    Seemed to work--- pretty accurate.
    T

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