Cleaning & Corrosion Control Flashcards
Name three forms of corrosion.
Surface, dissimilar metal, intergranular, filliform, fretting.
List three factors of corrosion.
Environmental, type of metal, dissimilar metals in contact, condition of protective coatings, presence of electrolytes and contaminants.
List procedures in corrosion prevention maintenance.
Cleaning, lubrication, inspection, seal protective covers, and clear drain holes.
Identify the areas of an aircraft that are most prone to corrosion.
Battery compartment, exhaust system and exhaust trails, wheel wells, lower area of the belly (bilge), piano hinges, areas of dissimilar metal contact, welded areas, inside of the fuel tanks especially integral tanks, metal fittings under high stress, lavatories and foodservice areas.
What tools are proper for removing corrosion from aluminum alloy?
Aluminum wool or aluminum wire brushes. Severe corrosion may be removed with a rotary file.
What are some necessary precautions during aircraft washing?
Avoid protected areas, bearings, hinges, sealed airs, and the pitot and static inlets.
Name light duty cleaning agents.
Soap and synthetic detergents.
Name heavy duty cleaning agents.
Solvents and emulsions.
Where is stress corrosion most likely to occur on an aircraft?
In any metal component that is continually under a tensile stress. The metal around holes in castings that are fitted with pressed-in bushings are susceptible to stress corrosion.
How may filliform corrosion look?
Blistered paint with worm or fern like patterns.
What is used to clean transparent plastic windshields and windows of an aircraft?
Mild soap and plenty of clean water.
Why should aluminum polish not be used on anodized surfaces?
The polish removes the protective oxide coating.
What is used to clean aircraft tires?
Soap and water.
Why should you use only the recommended cleaner on fabric and plastics?
They cause less deterioration.
Where is filiform corrosion most likely to occur on an aircraft?
Under a dense coating of topcoat enamel such as polyurethane. Filiform corrosion is caused by improperly cured primer.
Why clean before inspection?
To remove residues that could be hiding potential problems.
Why do piano hinges corrode easily?
Dissimilar metals are used in fabrication, and the basic design traps contaminants.
How should corrosion be minimized at piano hinges?
They should be kept as clean and dry as practicable and lubricated with a low viscosity moisture dispersing agent.
What can be used to repair the anodized surface of an aluminum alloy part?
A chemical conversion coating such as Alodine.
Should you use steel wool on aluminum? Why or why not.
No, causes corrosion.
What is Alodine used for?
It provides the oxide coat to protect aluminum alloy surfaces, and is also used as a substrate to help paint bond.
Where is fretting corrosion most likely to occur on an aircraft?
In a location where there is a slight amount of relative movement between two components, and no way for the corrosive residue to be removed as it forms. Fretting corrosion around rivets in a skin is indicated by dark deposits streaming out behind the rivet heads.
Where is dissimilar metal corrosion most likely to occur on an aircraft?
Anywhere different types of metal come in contact with each other, especially where moisture is present; for example, piano hinges.
What must be done to a piece of aluminum alloy to remove surface corrosion and to treat the metal to prevent further corrosion?
Remove the corrosion residue with a bristle brush or a nylon scrubber. Neutralize the surface with chromic acid or with some type of conversion coating. Protect the surface from further corrosion with a coat of paint.
What is used to keep corrosion from forming on structural aluminum alloy?
An oxide coating or aluminum cladding.
How may rust be removed from a highly stressed metal part?
By glass bead blasting, by careful polishing with mild abrasive paper or by using fine buffing compound on a cloth buffing wheel.
What is used to neutralize the electrolyte from a lead-acid battery that has been spilled on an aircraft structure?
A solution of bicarbonate of soda and water.
What is used to neutralize the electrolyte from a nickel-cadmium battery that has been spilled on an aircraft structure?
A solution of boric acid and water, or vinegar.
What solvent is recommended for removing grease from aircraft fabric prior to doping it?
Methyl Ethyl Ketone (MEK) or lacquer thinner.
What type of device is used to remove surface corrosion from a piece of magnesium alloy?
A stiff hog-bristle brush.
How is the inside of structural steel tubing protected from corrosion?
The tubing is filled with hot linseed oil and then drained.
Where is intergranular corrosion most likely to occur on an aircraft?
Along the grain boundaries of aluminum alloys that have been improperly heat-treated. Extruded aluminum alloy is susceptible to intergranular corrosion.
