ATO CORROSION
What four conditions must exist for corrosion to occur?
A metal must be present (Anode) Dissimilar Conductive material (Cathode) A conductive liquid (Electrolyte) Electrical contact between Anode and Cathode
What should you not do to depleted Uranium?
Abrade or sand
Exfoliation Corrosion
Advance form of intergranular corrosion where the surface grains are lifted up by the force of expanding corrosion products occurring at the grain boundaries just below the surface. Commonly found on Aluminum sheets around steel fasteners. Can be prevented by separating the metals with a barrier.
What must be done in order to guard against the danger of static electricity during all cleaning operations?
Aircraft must be electrically grounded
Volume II
Aircrafts- Provides cleaning and corrosion control procedures for aircrafts.
Intergranular Corrosion
An attack on the grain boundaries of a metal. Rapid Corrosion occurs at the grain boundaries of certain metals when an electrolyte is present.
What is mandatory when applying sealant whenever the previously applied sealant is damaged?
Apply fresh sealant
Highly susceptible to corrosion. This is especially true in helicopters and aircrafts using external ram air-cooling. Technicians should routinely survey this area.
Avionics Equipment Bay
Volume III
Avionics and Electronics- Provides cleaning and corrosion control procedures for avionics and electronics.
This areas contain all types of avionic equipment, providing many places for the following substances to accumulate: dirt, water, Hydraulic fluid, drill shavings, waste, loose fasteners, others debris.
Bilge Area
The three general equipment areas that are COMMONLY affected by corrosion are?
Bilge Area Equipment Bay Area Engine Compartment
Tools used for applying sealant.
Brush Spatula Masking Tape Caulking Gun
Preferred alternatives for touch-up painting since they produce little paint waste and do not require solvent clean up.
Brush and Rollers
What tools are used to apply Paint coating?
Brushes Touch-Up pens Rollers Spray Guns
Crevice Corrosion
Can occur where a stagnant solution has pooled and an electrolyte inside the crevice contains less oxygen and more metal ions than electrolytes outside the crevice.
Volume V
Consumable Materials and Equipment for Avionics- Lists approved materials and equipment for cleaning and corrosion control, and provides ordering information, for avionics only. AIR FORCE ONLY
Volume IV
Consumable Materials and Equipment for aircraft and avionics- Lists approved materials and equipment for cleaning and corrosion control, and provides ordering information.
Prior to using Sealant...
Container must be inspected to determine if the material has exceeded its shelf life.
NAVAIR 01-1A-509
Contains basic corrosion prevention and maintenance information to be used at the Organizational, Intermediate, and Depot levels.
Volume I
Corrosion Program and Corrosion Theory- provides overall program information and explains what corrosion is, why it occurs, the forms it can take, and how to recognize it.
Hot Corrosion
Corrosion in the absence of water can occur at high temperatures, such as those found in turbine engine, compressors, and hot sections.
Fatigue Corrosion
Cracking of metals caused by the combination of fatigue and corrosion. It can cause a reduction in fatigue resistance.
How does a Circulating Drying Oven work?
Dries avionic equipment and components using circulating air and temperature.
Depends on the complexity of the equipment or component being dried and the amount of humidity in the air.
Drying time
Area containing hardware, electrical connectors, terminal boards, junction boxes and ram air turbine which should be inspected for signs of salt spray contamination and corrosion.
Engine Compartment
Magnesium Parts
Extremely prone to corrosion. Special attention must be given to proper treatment of their surfaces, insulation, and paint coating.
The key to successful preventive maintenance
Frequent Inspections and Spot Checks
What is Rubber subject to?
Fungus Growth, which can cause deterioration of the rubber and corrosion of surrounding metal surfaces.
What are the Operational Uses for the Paint System?
Glare Reduction by flat coating Special finishes for reduction of heat absorption Camouflage and other detection countermeasures High visibility requirements Identification markings
Methods of applying Lubricants
Grease guns: lever or pressure type Oil, squirt and aerosol spray cans Hand or brush
Why are Water Entrapment ineffective?
Improper location or because they are plugged by sealants, fasteners, dirt, grease, or debris.
Condensation
Is produced by closed boxes
Two types of batteries found on avionic equipment are?
Lead acid Nickel- Cadmium
Degrees of Corrosion
Light Corrosion Moderate Corrosion Severe Corrosion
Method of fixing Light Corrosion
Light hand-sanding
Moderate Corrosion
Looks like corrosion except that there may be some blisters or evidence of scaling and flaking of the coating or paint system, and the pitting depths may be as deep as 10 mils (0.010 in).
Severe Corrosion
May be similar to moderate corrosion with severe inter granular corrosion, blistering exfoliation, scaling, or flaking. The pitting depths are deeper than 10 mils (0.010 in).
Pitting Corrosion
Most commonly found on Aluminum and Magnesium Alloys. White or Gray powdery deposit, similar to dust, which blotches the surface. When sheet metals become weak they can perforate.
Fretting Corrosion
Occurs at contact areas between materials under load subject to repeated vibrations. Aluminum, Stainless Steel, and Titanium alloys are most susceptible to this type of corrosion because the movement removes oxide coatings.
Galvanic Corrosion
Occurs when different metals are in contact with each other and an electrolyte such as salt water.
The date of manufacture and shelf life can be found where on the sealant?
On each container
New sealant should...
Overlap the existing coating on the roughened surface.
Lubrication
Performs as a dual purpose. Prevents wear between moving parts, but also fills air spaces, displaced water, and provides a barrier against corrosive medium.
Human waste
Products are very corrosive. Areas should be cleaned frequently and the paint finish kept in good condition. Relief tubes are usually made of plastic and should not present a corrosion problem.
Light Corrosion
Protective coating is scarred or etched and the condition of the metal is characterized by discoloration and pitting to a depth of approximately one mil (0.001 in) maximum.
Who selects what methods has to be used when dealing with corrosion?
Qualified Personnel
Air Drying
Recommended for housings, covers and some hardware. It should NOT be used for equipment containing cavities or moisture traps.
What must you do for cold weather cleaning procedures below 40F?
Refer to NAVAIR 01-1A-509-2 Chapter 2
Method of fixing Moderate Corrosion
Removed by extensive hand-sanding or light mechanical sanding.
Method of fixing Severe Corrosion
Removed by extensive mechanical sanding or grinding.
Uniform Surface Corrosion
Results from a direct chemical attack on a metal surface and involves ONLY the metal surface. The metal gradually becomes thinner and eventually fails.
Prevents the intrusion of moisture, rain, saltwater, dust, and aircrafts fluids, which can lead to extensive corrosion. ONE OF THE MOST IMPORTANT TOOLS FOR CORROSION PREVENTION AND CONTROL.
Sealants
What should you not do with the portable 15 & 45 gallon Foam Generating Cleaning Unit without releasing pressure?
Service it
What should you not do to Natural and Synthetic Rubber?
Shall not be Painted or oiled
Must be removed to facilitate inspection. They are usually the last items to. be inspected for corrosion damage.
Shock Mounts
Lubricant should be applied....
Sparingly to prevent accumulation of dust, dirt, and other foreign matter. Any excess should be wiped away.
Filiform Corrosion
Special form of oxygen concentration cell corrosion or crevice corrosion which occurs on metal surfaces having an organic coating system. Recognized by characteristic wormlike traces of corrosion products beneath the paint film.
The Environmental Protection Agency (EPA) has established specific requirements for using this method to be used on aircraft surfaces
Spray Painting
Corrosion
The electrochemical deterioration of a material or its properties due to its chemical reaction with the surrounding environment.
Solvent Vapor Drying
The fastest and most efficient means of drying. Uses Solvent Ultrasonic Cleaner to dry by means of evaporation. Drying time is usually 15 seconds to 3 minutes.
Forced Air Oven
The most efficient drying oven and be used to dry all types and sizes of equipment and components.
Human Eye
The most useful tool for detection of corrosion.
What must be done if the protective finish which covers the depleted Uranium is chipped, peeled, or otherwise removed so the dark gray or black depleted Uranium is visible?
The part must be returned to the licensee for rework or disposal.
What is the primary objective of the Paint System?
To protect all exposed surfaces against corrosion and any other forms of deterioration.
10X Magnifying Glass
Tool used to find and evaluate the extent of corrosion damage.
The most common type of corrosion.
Uniform Surface Corrosion
Circulating Air drying oven
Used to dry small electrical and electronic components, such as unpressurized instruments, control boxes, printed circuit boards and similar devices. Should NEVER be operated over 130F.
Detailed Inspection
Very effective fro detecting surface corrosion if done carefully and with the knowledge of where and what to look for.
What must you do for hot weather cleaning procedures above 80F?
Wet aircraft exteriors with fresh water before cleaning will cool surfaces and help prevent fast evaporation.
Moisture
What is the biggest contributor to corrosion in avionics?
Design Step
When is the best time to prevent corrosion?
Every 7 days
When should a Navy Aircraft be cleaned when aboard a ship?
Every 14 days
When should a Navy Aircraft be cleaned when ashore?
Daily cleaning of an aircraft is required when....
deployed within 3 miles of salt water or when flown below 3000 feet over salt water.
Sealant may be ______________ of their original shelf life after passing the required test.
one-half