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CLEANING & CORROSION CONTROL FINAL
HIGH-YIELD SURFACE TREATMENT,
INSPECTION, AND SAFETY PROCEDURES
SUMMARY 2026
โ What action creates the cause that leads to intergranular corrosion? Answer: Changes that occur in the alloy during the heating and cooling process of the material's manufacturing. โ According to the text, metal corrosion is the _____ of the metal by _____ or _____ attack. Answer: - deterioration
- chemical
- electrochemical โ What is the most severe climate in which to operate an aircraft when considering corrosion characteristics? Answer: marine environments (exposure to sea water and salt air) โ T/F - Using two different types of metals in aircraft construction is an excellent way to eliminate corrosion.
Answer: False โ What causes fretting corrosion? What is a common example of fretting corrosion found on engine cowlings and wing skins? Answer: - 2 mating surfaces, normally at rest with each other, experience relative motion
- smoking rivet on engine cowling or wing skin โ What is the basic cause of intergranular corrosion? Answer: Lack of uniformity in the alloy structure. โ When looking at an area of corrosion involving two materials, how can we tell which one is the anode, and which is the cathode? Answer: The anode will be the one that is the most severely corroded. โ What are the two general classifications of corrosion? Answer: - chemical
- electrochemical โ T/F - Intergranular corrosion is the easiest form of corrosion to detect. Answer: False
โ If aluminum and stainless steel are riveted together at a lap joint, _____ is the cathode. Answer: stainless steel โ If aluminum and magnesium are riveted together at a lap joint, _____ is the anode. Answer: magnesium โ An _____ _____ is an atom that has more electrons than protons Answer: negative ion โ T/F - Control cables should always remain clean and dry, with no products applied which could mask potential problems. Answer: False โ The cost of returning an aircraft which has had negligible corrosion control done over an extended period of time is [x]. (minimal, high) Answer: high โ What two things should be done to prevent corrosion in areas associated with batteries?
Answer: - clean and inspect vent openings
- clean and neutralize acid deposits โ How often should inspections be done on an amphibious or seaplane? Are there any other precautions that should be taken with this type aircraft? Answer: Daily. Critical areas should be cleaned or treated as necessary. โ A _____ _____ is a natural gathering place for waste hydraulic fluids, water, dirt, and other debris. Answer: bilge area โ T/F - The heat from exhaust outlets tends to keep metal surfaces dry, thus preventing corrosion. Answer: False โ What is the easiest and most cost efficient method of corrosion control? Answer: Keeping the aircraft clean โ What area on an aircraft probably gets the most punishment? Answer: the landing gear and the wheel well
- Smoking at Rivets โ Give 3 reasons why wheel wells are such a hard area to protect from corrosion. Answer: - Abrasion
- dirt and grease
- Chemical attack
- Galvanic corrosion
- Electrical components
- Complex assemblies โ What type of inspection could be used to detect stress corrosion? Answer: Dye Pen (or Eddy Current) โ What type of inspection could be used to detect intergranular corrosion? Answer: Ultrasound or X-Ray. โ What are four electrolytes (corrosive agents) found in aviation? Answer: Water Air Acids/alkalis
Microbial/organic growth Mercury Salts โ Why are piano hinges prone to corrosion? Answer: due to two dissimilar metals in contact in-between the hinge and the rod โ Name four primary tools needed to find corrosion during a visual inspection. Answer: - Eyes
- Mirror
- Light
- Borescope
- Magnifying Glass
- Scribe or Cleaning Tools โ During a 100 hr inspection on a small aircraft, in what three areas would you take extra time because they are corrosion prone areas? Answer: - Engine Exhaust area
- Battery Compartment
- Engine Mounts
โ What type grit is not to be used when blasting aluminum parts? Answer: steel grits โ T/F - Using window cleaner (i.e. Windex) on plastic windshields is an acceptable method of cleaning them. Answer: False โ Accumulated grease and dirt can be detrimental to an engine in what two ways? Answer: - Hide defects
- Reduce cooling โ _____ and _____ are two corrosion-preventative chemical treatments on aluminum that also aid in paint adhesion. Answer: - anodizing
- alodining (alodizing) โ Unless recommended by the manufacturer, what tools should not be used during propeller cleaning? Answer: Scrapers, power buffers, steel brushes, or any tool or substances that mar or scratch the surface.
โ As a cleaner or paint stripper for small areas, _____ is a good option, although it must be used with care, as it is toxic. Answer: MEK โ Between aliphatic and aromatic naphtha, _____ naphtha is preferred for cleaning acrylics and rubber? Answer: aliphatic โ _____ _____ is the preferred product to be used in cleaning lead-acid battery areas. Answer: baking soda โ T/F - One should never grit blast magnesium. Answer: False โ What are the 2 desired effects of alodining? Answer: Slightly roughen the surface & increase corrosion resistance. โ Match the chemical to the proper precaution or proper use. Answer: Mild soaps and detergents - safe on all surfaces Aromatic naphtha - harmful to rubber Emulsion cleaners - used on heavy deposits
โ Before a corrosion damage can be properly assessed a surface must be prepared. What are the two main steps of surface preparation? Answer: Cleaning and paint removal. โ What are the three steps of corrosion treatment? Answer: - Remove corrosion
- neutralize residual
- restore protective coating โ What has generally replaced aluminum wool, aluminum wire wheels, and fiber bristle brushes as the tool of preference for cleaning corroded anodized surfaces? Answer: Non-woven abrasive pads. โ What type bristle brush is to be used to clean magnesium? Answer: Stiff, hog bristle brush. โ One of the most severe corrosions found in aluminum, which can necessitate replacement of the part, is _____ _____ Answer: intergranular corrosion
โ [x] scrapers are the only type of scraper that should be used when removing persistent paint finishes. Answer: nonmetallic โ In what areas does magnesium skin corrosion happen? Answer: Edges of skin panels, underneath washers, in areas physically damaged by shearing, drilling, abrasion, or impact. โ What is one precaution when using chemical paint remover? Answer: - Must use adequate ventilation
- Must protect synthetic surfaces from the stripper. โ [x] is the most chemically active of all the metals. Answer: magnesium โ T/F - Rust actually forms a layer of protection for the underlying metal surface. Answer: false โ T/F - Some corrosion can be a good thing on some aluminum parts. Answer: True
Answer: - neutralizes residual corrosion
- cleans aluminum
- roughens surface for painting โ The preferred method of corrosion removal on magnesium is [x ]? Answer: Grit blasting (stiff hog brush can also be used) โ The three categories for protecting aluminum Answer: - cladding
- artificial oxide film
- organic film โ
