TEST 1 2025.pdf

What does salt do to an aircraft’s exterior: Salt acts as an electrolyte that breaks down the protective oxide layer of an aircraft Cleaning agents: Solvents : heavy duty cleaning (ex: MEK) Emulsion Cleaners:heavy duty cleaning Soaps: light cleaning (gentlest type of cleaners,...

What does salt do to an aircraft’s exterior: Salt acts as an electrolyte that breaks down the protective oxide layer of an aircraft Cleaning agents: Solvents : heavy duty cleaning (ex: MEK) Emulsion Cleaners:heavy duty cleaning Soaps: light cleaning (gentlest type of cleaners, non-toxic, non-flammable) Synthetic detergents: light cleaning (Non-soap type cleansers,non-toxic, non-flammable) Solvent emulsion cleaners: Useful in the removal of heavy deposits, such as carbon, grease, oil, or tar. Do not affect good paint coatings. What to remember when using cleaners: Always use them in accordance with the maintenance manual. How to prevent corrosion in cleaners: Use cleaners that can be effectively rinsed and neutralized. What could an alkaline cleaner cause? : An alkaline cleaner may cause corrosion within lap joints in sheet metal components. What are the three methods of washing an aircraft?: Wet wash, Dry wash, Polishing Wet wash: alkaline cleaners, emulsion cleaners applied by spray or mop. Removes oil, grease, carbon deposits, most soils. Does not remove corrosion and oxide films. Dry wash: Dry mopping or clean, dry cloths. Removes airport film, dust, small accumulations of dirt and soil. Polishing: MM for product. Restores luster to painted surfaces, removes oxidation and corrosion. On an exterior Cleaning what shouldn't you use?: Stiff brushes or coarse rags oil or exhaust stains on the surface should first be removed with what?: A solvent such as kerosene and other petroleum base solvent. Dry an aircraft with what?: Chamois, Synthetic wipes, Absorbent cotton What to do with plastic surfaces?: Not rub with dry cloth, do not use scouring powder or other material that can scratch. Clean gently with wet cloth with soap and water. Harmful products can soften the plastic and cause crazing (cloudiness) Aircraft tires: cleaned with mild soap and water to remove oil, hydraulic fluid, grease and fuel. After cleaning: Lubricate all grease fittings, hinges Alkaline cleaners: No fire hazard(water soluble) Acid solutions: Best cleaners to remove carbon deposits and corrosive stains from cabin area. 1. Class I: flash point below 100 fahrenheit Cleaning oxygen systems: Isopropyl alcohol What should we do when going from one metal to another with our sanding pad?: replace it, same pad should not be used on different metals. Aluminum wool grades: Coarse, medium, fine. Aluminum oxide paper characteristics: 300 grit or finer, several forms, safe to use on most surfaces. 2 Categories of corrosion: 1. Chemical corrosion: Direct exposure of a bare surface to a caustic liquid or gaseous agent 2. Electrochemical corrosion: When two dissimilar metals are in contact with each other in the presence of an electrolyte. Electrochemical corrosion needs what? : Anode, Cathode, an electrical path between them, an electrolyte. Eliminate ¼ and you now dont have corrosion. Anode: A metal subject to corrosion Cathode:A dissimilar conductive material Oxidation: Chemical reaction takes place between metal and oxygen. Surface corrosion: Exposed to an atmosphere containing battery fumes, exhaust gases etc. trapped moisture, left for long time. Pitting: Untreated surface corrosion Galvanic: two dissimilar metals make electrical contact. Crevice: Damage in the lap of joints of aircraft skins. Filiform: beneath coatings(paint) Intergranular: Improper heat treatment of aluminum alloy in the 2000 series Exfoliation: Extruded type structures Stress: Along grain boundaries that have cracks present in stressed or overstressed conditions. Fretting: When there is movement between two surfaces and oxygen Types of (NDT): 1. Magnetic particle inspection 2. Dye penetrant inspection 3. Visual inspection 4. Eddy current inspection 5. Ultrasonic inspection 6. Radiographic inspection Methods of detecting corrosion: 1. Visual inspection 2. Dye pretrant inspection 3. Magnetic particle inspection 4. Eddy current 5. Ultrasonic inspection 6. X-RAY inspection Corrosion limits: 1. Negligible damage 2. Damage repairable by patching 3. Damage repairable by insertion 4. Damage necessitating replacement of parts Conversion coating: Forms a protective film on surface of bare metal and eliminates further corrosion action Sacrifical coating: Metal is coated with more reactive metal the coating corrodes faster. (cadmium) Anodizing: Dipping aluminum into acid electrolyte bath and passing electric current through it Alclad: Coating of pure aluminum (1100) on aluminum alloy Volatility: A measure of the tendency of a substance to vaporize Flash point: Lowest temp for material to ignite Methods of applying finish: Dipping, brushing, spraying Zahncup: Used to measure paint viscosity Common paint problems: Fish-eye,Sanding scratches,wrinkling