Cleaning and Corrosion Control Flashcards
What is used to clean transparent plastic windshields and windows of an aircraft?
Mild soap and lots of clean water.
What is used to neutralize the electrolyte from a lead-acid battery than has been spilled on an aircraft structure?
A solution of bicarbonate of soda and water.
What is used to neutralize the electrolyte from a Ni-Cad 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 is the proper way to clean plastics?
Flush the plastic with clean water. Remove dirt by hand. Plastics are easily scratched and usage of rags is not recommended.
What causes corrosion?
Corrosion is a natural phenomenon that attacks metal by chemical or electrochemical action and converts it into a metallic compound, such as an oxide, hydroxide, or sulfate. Noble metals like gold and platinum do not corrode since they are chemically uncombined in their natural state. Conditions that can cause corrosion to develop or worsen are moisture )acts as an electrolyte), oxygen, (acts as a catalyst, chemicals (initiate or catalyze the electromechanical process), and temperature ( accelerates the process).
Where is filliform 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.
Where is fretting corrosion most likely to occur on an aircraft?
In a locating 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.
Where is intergrannular 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.
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 fitted with pressed-in bushings is susceptible to stress corrosion.
What areas of an aircraft 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 fuel tanks (especially integral tanks), metal fitting under high stress, lavatories, and food service areas.
What is used to keep corrosion from forming on structural aluminum alloy?
An oxide coating or aluminum cladding.
How should and A & P minimize corrosion at piano hinges?
Piano hinges should be kept as clean and dry as practicable and lubricated with a low-viscosity moisture dispersing agent.
How is the inside of structural steel tubing protected from corrosion?
The tubing is filled with hot linseed oil and then drained.
How does filiform corrosion usually appear on an aircraft structure?
As thread-like lines of puffiness under a film of polyurethane or other dense finish system topcoats.
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.
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 tools are proper for removing corrosion from aluminum alloy?
Aluminum wool or aluminum wire brushes. Sever corrosion can be removed with a rotary file.
What type of device is ued to remove surface corrosion from a piece of magnesium alloy?
A stiff hog-bristle brush.
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.
How is rust 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 a corrosion preventive compound (CPC)?
CPC is a waxy sealant or thin-film dieletric that can be sprayed into aircraft structures to coat the surfaces and work its way between skins to prevent corrosion.
What type of environment would CPCs normally be used in?
CPCs are used on corrosive environments such as aerial agricultural spray operations and saltwater environments.
How are CPCs applied to aircraft?
CPCs are normally applied with high-pressure spray equipment that creates a fog of the CPC material inside the aircraft structure. Long spray wands are used to reach difficult-to-access areas.
What is used to clean a composite material prior to repair?
Acetone or MEK is commonly used. It is important to verify that the solvent reside is compatible with the resin system.
Where is a 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.
