Chapter 12 - Cleaning and Corrosion - Oral Questions Flashcards
Is there any requirement for cleaning an aircraft prior to an annual or 100 hour inspection?
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 (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, worm or thread-like tracks under the paint
What are 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?
Corrosion residue has a dark, smoky appearance and often appears around and streaming back from rivet heads
(smoking guns)
Why are piano-type hinges prime spots for corrosion?
The steel pin and aluminum hinge material are dissimilar metals and the 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
Describe the tools that should be used to remove corrosion from aluminum surfaces
Nylon scrubber pads (scotch brite),
bristle brushes,
aluminum wool or
aluminum wire brushes
Describe the effects of using steel brushes or steel wool to remove corrosion from aluminum surfaces
Steel brushes or steel wool must not be used to clean aluminum because steel particles can become embbedded in the aluminum and cause corrosion
What is the purpose of alodine?
Alodine is a chemical process that deposits a protective film on aluminum alloys. This film improves corrosion reistance and paint adhesion
For what reason should you avoid cleaning anodized aluminum surfaces with aluminum metal polish
The polish removes the protective oxide coating
Why should aircraft fabrics and plastics be cleaned only with recommended cleaners?
They cause the least amount of deterioration or damage
List at least five areas of an aircraft prone to corrosion
1) Battery compartments
2) Exhaust trail areas
3) Bilge areas
4) Vent areas
5) Landing gear and wheel wells
6) Fuel tanks
7) Wing flap recesses
8) Around and below galleys and lavatories
9) Piano Hinges
10) Any area that can trap water
