General Chapter 12 Flashcards
Cleaning and Corrosion
Is there any requirement for cleaning an aircraft prior to an annual or 100 hour inspection?
It is not only good, common sense, but it is a legal requirement as specified in FAR Part 43, Appendix D.
Discuss the general precautions that should be observed when washing an airplane.
Avoid or protect areas, which may be damaged or contaminated, such as: Pitot and static ports, hinges, sealed areas, and bearings.
What are some of the more common light-duty cleaning agents?
Soap or detergents and water.
What materials are commonly used as heavy duty cleaners?
Solvents and emulsions.
What are the preferred cleaners for plastic surfaces such as windshields?
Mild soap and water or a manufacturer approved cleaner.
What type of cleaning agents should be used to remove grease, oil or fuel from aircraft tires?
Soap and water.
Give at least three examples of the factors that cause or influence corrosion.
(1) The environmental conditions (2) The presence of dissimilar metals. (3) The type of metal. (4) The presence of electrolytes and/or contaminants. (5) The condition of protective coatings.
Name at least three forms of corrosion.
(1) Surface. (2) Intergranular. (3) Filliform. (4) Dissimilar metal (or galvanic). (5) Oxidation. (6) Pitting. (7) Stress. (8) Fretting.
Name at least one cause of filliform corrosion.
(1) Improper or incomplete curing of a wash primer prior to painting. (2) Failure to completely wash off acidic surface contamination.
What are the visible signs of filliform corrosion?
Blistered paint surfaces or worm or thread-like tracks or patterns under the paint.
What are the two primary factors that may cause development of stress corrosion cracks?
A corrosive environment and sustained tensile stress.
What are the visible signs of fretting corrosion?
The corrosion residue has a dark, smoky appearance and often appears around and streaming back from rivet heads.
Why are piano-type hinges prime spots for corrosion?
The steel pin and aluminum hinge material are dissimilar metals and he hinge design tends to trap moisture and contaminants.
What is the best way to protect piano hinges from corrosion?
Keep them clean and properly lubricated.
Provide at least four examples of procedures used to prevent corrosion.
(1) Cleaning (2) Lubrication (3) Treatment (4) Sealing (5) Inspection (6) Installing protective covers (7) Keeping drain holes free and clear.
