(e)
Shot-peen the brake mounting flanges and the adjacent axle areas after a fuse plug has melted. Do the shot-peen when schedules permit, but not later than the landing gear overhaul.
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(8)
Remove the antiskid transducers (Ref 32-42-11/401).
(9)
Examine the paint (green primer or light gray enamel) on the inner surfaces (bore) of the axle with a borescope. Use the borescope to a minimum depth of 16 inches. Look for discoloration or blistering.
(a)
Green paint will change to a light brown or black color.
(b)
Light gray paint will change to a yellow color.
(c)
If the plating shows signs of heat damage, do the heat damage inspection procedure.
(d)
If the paint show only a smal discoloration, more heat damage inspecitons can wait. Do the last part of the inspection when the airplane gets back to the primary base. Do not land more than three times before you do this inspection.
3. Heat Damage Inspection
A. General
(1)
This inspection is used to find if the high strength steel that showed signs of heat damage, had changed. It will look for a change in the temper or heat treat properties.
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.
(2)
This inspection will usually occur on the components of the landing gear axles. The signs of discolored or blistered paint or plating shows that a general intense heat has changed the temper of the axle. When this happens, the ammonium persulphate procedure should be applied to the damaged part of the axle. Do this procedure after the axles have been reworked. Axle rework procedures can be found in Chapter 32, Landing Gear.
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B. Consumable Materials
(1)
Air - Clean, dry, compressed
(2)
Ammonium persulphate etch solution
(a) 100 grams of ammonium persulphate per 0.27 gallon of tap water
(3)
0231 Methyl or Isopropyl Alcohol - TT-1-735 (Ref 20-30-31)
(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) 32-45-11/401, Main Gear Wheel Well and Tire - Removal/Installation
D. Ammonium Persulphate Solution Procedure
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.
(a) Strip a minimum area of 0.5 inch larger than the area that is to be tested.
(2)
Clean the area to etched, with solvent.
(3)
Apply the ammonium persulphate solution, with a cheesecloth, on the surface to be tested for 30 to 60 seconds.
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.
(5)
Dry the surface with clean, dry compressed air immediately.
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E. Examine etched area.
(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 darder 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.
F. Put the airplane back to its usual condition.
(1)
Remove the etch with abrasive paper.
NOTE: Do this step if the part is servicable. If it is not serviceable, install replacement parts. 中国航空网 www.aero.cn 航空翻译 www.aviation.cn 本文链接地址：737 AMM 飞机维护手册 时间限制 TIME LIMITS(27)
