Aviation Maintenance Technician Series General textbook ASA Chapter 8
Aviation Maintenance Technician General Handbook FAA-H-8083-30A FAA Chapter 8
1. 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 fuel tanks especially integral tanks, metal fittings and under high stress, lavatories and foodservice areas.
2. 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.
3. 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.
4. 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.
5. 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.
6. 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.
7. 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.
8. What is used to keep corrosion from forming on structural aluminum alloy?
An oxide coating or aluminum cladding.
9. 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.
10. 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.
11. What tools are proper for removing corrosion from aluminum alloy?
Aluminum wool or aluminum wire brushes. Severe corrosion can be removed with a rotary file.
12. What is used to clean transparent plastic windshields and windows of an aircraft?
Mild soap and plenty of clean water.
13. 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.
14. 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.
15. What solvent is recommended for removing grease from aircraft fabric prior to doping it?
Methyl Ethyl Ketone (MEK) or lacquer thinner.
16. What can be used to repair the anodized surface of an aluminum alloy part?
A chemical conversion coating such as Alodine.
17. What type of device is used to remove surface corrosion from a piece of magnesium alloy?
A stiff hog-bristle brush.
18. How is the inside of structural steel tubing protected from corrosion?
The tubing is filled with hot linseed oil and then drained.
1. Given samples of corroded aircraft structural materials, identify the type of corrosion and describe the correct procedure for removing the corrosion and treating the damaged area to prevent further corrosion.
2. Remove the corrosion from a piece of aluminum alloy furnished by the examiner and treat the metal to prevent further corrosion.
3. Treat a piece of aircraft structure so moisture cannot reach the metal and cause corrosion.
4. Select the proper cleaning materials and remove grease and exhaust deposits from an aircraft structure.
5. Select the proper cleaning materials and remove oil that has been spilled on an aircraft tire.
6. Demonstrate to the examiner the correct way to remove rust from a highly stressed engine component.
7. Properly remove the finish from a piece of painted aluminum alloy.
8. Properly remove the finish from a piece of painted fiberglass reinforced plastic material.
9. Demonstrate the correct way to clean a transparent plastic cockpit enclosure or windshield.
10. Remove corrosion from a lead-acid battery box and treat the box to prevent further corrosion.
11. Treat the cylinders of a reciprocating engine to prevent rust and corrosion when the engine is being prepared for long-term storage.
12. Treat a piece of welded steel tubular structure to prevent rust and corrosion inside the tubing.