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Thread: Sanding/Striping paint off spring steel landing gears

  1. #1

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    May 2012
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    Sanding/Striping paint off spring steel landing gears

    I have a 1956 Cessna 180 and would like to temporarly repaint the landing gear until I can have a complete paint job. I have received comments from mechanics, experienced individals etc., equally with polar opinions. Some say sanding gently into to steel of the gear to remove the corrosion is OK, just don't leave any grooves, or perpendicular scratches to the grain. Others have responded to never sand the spring steel Cessna gear at all, ie, do not remove any surface material or 90% of the spring steel tensile strength is gone. Use only glass bead sand blasting, etc.

    Any thoughts or experience out there on this topic? I am attempting to get a good education on this.

  2. #2

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    Paint stripper will remove the paint. The rust that remains can be sanded off with fine sandpaper (400).
    A smooth sanded surface is better than rust pits for fatigue cracking. Done this many times on Cessna 180's.
    Don't worry about the slight metal removed.
    But in any case, always check the Cessna service manual first.

  3. #3

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    Soda blasting will remove both paint and rust with no damage.

  4. #4

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    Bill and vaflier, Thank you both for your comments. I will also check with the Cessna service manul.
    towpilot

  5. #5

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    Quote Originally Posted by towpilot View Post
    I have a 1956 Cessna 180 and would like to temporarly repaint the landing gear until I can have a complete paint job. I have received comments from mechanics, experienced individals etc., equally with polar opinions. Some say sanding gently into to steel of the gear to remove the corrosion is OK, just don't leave any grooves, or perpendicular scratches to the grain. Others have responded to never sand the spring steel Cessna gear at all, ie, do not remove any surface material or 90% of the spring steel tensile strength is gone. Use only glass bead sand blasting, etc.

    Any thoughts or experience out there on this topic? I am attempting to get a good education on this.
    You can sand the gear to remove old finish and any corrosion. Make sure you use aluminum oxide only. 150 grit is good for corrosion removal and blending, 400 grit for finishing. If you don't have experience doing this, do it by hand, no power tools. Check for any pitting in the finish, the new Cessna aging aircraft criteria has limits for pitting depth and it's not much. I think you can blend anything up to that depth out at 20:1. I can check the specifics when I get home. Do NOT use acid based paint stripper on your gear legs, due to the potental for hydrogen embrittlement.

  6. #6

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    I have never done spring landing gear but I do like crushed glass as a medium as it does a great job.. It doesn't have the contaminates like raw silica sand or even black beauty. I have used wheat starch and it takes off paint but is of little use on rust. Maybe someone had a better medium than I did.
    Last edited by RV8505; 05-22-2012 at 12:59 PM.

  7. #7

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    Quote Originally Posted by RV8505 View Post
    ... crushed glass...doesn't have the contaminates like silica...
    stupid me. i thought glass IS silica:

    "Silica is a common fundamental constituent of glass."

    http://en.wikipedia.org/wiki/Glass

    "Any corrosion on the surface of a highly stressed steel part is potentially dangerous, and the careful removal of corrosion products is required. Corrosion products must be removed by careful processing, using mild abrasive papers such as rouge or fine grit aluminum oxide, or fine buffing compounds on cloth buffing wheels."

    faa-8083-30 chapter 6

    "4.3.4 CORROSION REMOVAL. Abrasive blasting is the preferred method of removing corrosion; other mechanical methods (SSPC SP-2 or SSPC SP-3) that may be used are grinding, chipping, sanding, or wire brushing. Chemical corrosion removal may be used when there is no danger of the chemical becoming entrapped. Phosphoric-acid- type remover must not be used on high-strength steel heat treated above 1.24 gigapascals (GPa) [180,000 pounds per square inch (psi)] tensile strength because of possible stress corrosion or hydrogen embrittlement problems."

    NASA tech manual 584c

    your mileage may vary.

  8. #8

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    Sorry I meant raw silica sand.

    I have never done spring landing gear but I do like crushed glass as a medium as it does a great job.. It doesn't have the contaminates like raw silica sand or even black beauty. I have used wheat starch and it takes off paint but is of little use on rust. Maybe someone had a better medium than I did



    http://newageblastmedia.com/


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    Last edited by RV8505; 05-22-2012 at 01:10 PM.

  9. #9

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    May 2012
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    100 series manintenance manual

    Temporary revision TR5 on the pre-1962 Cessna 100 series maintenance manual, p/n D138-1-13, specifies the procedures for cleaning rust from the gear legs. Basically NO chemical stripping. Top suface pits can be sanded to a max depth of .063". Bottom suface to a max .012" depth before having to re-shot peen.

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