(2)
Ammonium persulphate etch solution
(a) 100 grams of ammonium persulphate per 0.27 gallon of tap water
(3)
Methyl or Isopropyl Alcohol - TT-1-735 (Ref 20-30-02)
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(4)
G00034 Cheesecloth
(5)
Brushes
(6)
B00183 Trichloroethylene Solvent - BMS 11-6, types I and II
(7)
G00270 Masking tape
(8)
B00168 Wet and Dry Abrasive Paper - Number 400 or finer
C. References
(1) 32-45-01, Main Gear Wheel Well and Tire - Removal/Installation
D. Ammonium Persulphate Solution Procedure
S 122-043
WARNING: DO NOT BREATHE THE VAPORS OF THE SOLVENTS OR ETCH SOLUTIONS.
_______ DO NOT GET THEM IN YOUR EYES, ON YOUR SKIN OR ON YOUR CLOTHES. INJURY TO PERSONS MAY OCCUR.
(1)
Strip the cadmium surface with sandpaper applied by hand. Strip a minimum area of 0.5 inch through the area that is not to be tested.
S 112-034
(2)
Clean the area to be etched, with solvent.
S 282-035
(3)
Apply the ammonium persulphate solution, with a cheesecloth, on the surface to be tested for 30 to 60 seconds.
S 162-042
WARNING: DO NOT LET THE ETCHANT SOLUTION TOUCH THE CADMIUM PLATED
_______ SURFACES. POISONOUS FUMES CAN OCCUR AND CAUSE INJURY TO PERSONS.
(4)
Rinse the surface with hot or cold water immediately. Alcohol can also be used.
S 162-037
(5)
Dry the surface with clean, dry compressed air immediately.
E. Examine etched area.
S 212-038
(1) Examine the parts with a bright light and without magnification. Look for signs of burning.
(a)
If all of the etched area is the same shade of gray, there will be no change to the temper of the steel.
(b)
The area that has been too hot will be light in color. Look for the light color in the center of a darker area.
(c)
If the etched area is mottled, the condition of the heat treat is not sure. Replace the axle or do a high quality metallurgical test.
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F. Put the airplane back to its usual condition.
S 122-039
(1) Remove the etch with abrasive paper.
NOTE:____Do this step if the part is serviceable. If it is not serviceable, install replacement parts.
S 372-040
(2)
Refinish the surface with the correct primer and paint.
S 422-041
(3)
Install replacement tires and wheels (Ref 32-45-01).
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