REFERENCES:

A. NAVEDTRA 12338, AVIATION STRUCTURAL MECHANIC (H&S) 3 & 2
B. NAVAIR 01-1A-509, AIRCRAFT WEAPONS SYSTEM CLEANING AND CORROSION CONTROL
C. NAVAIR 06-1-540, AVIONICS CLEANING AND CORROSION PREVENTION CONTROL

124.1 DEFINE CORROSION AS IT RELATES TO NAVAL AIRCRAFT. (REF A)

THE DETERIORATION OF A MATERIAL, USUALLY A METAL, BECAUSE OF A REACTION WITH ITS ENVIRONMENT.

124.2 EXPLAIN THE FOLLOWING TYPES OF CORROSION. (REF A)

A. UNIFORM SURFACE CORROSION - DIRECT CHEMICAL ATTACK ON A METAL SURFACE WITH OXYGEN IN THE AIR.

B. GALVANIC - KNOWN AS DISSIMILAR CORROSION, RESULTS FROM COUPLING OR JOINING OF TWO DISSIMILAR MATERIAL OF DIFFERENT ELECTRO-CHEMICAL POTENTIAL; THAT IS AN ANODE AND A CATHODE. CORROSION THEN OCCURS IN THE PRESENCE OF AN ELECTROLYTE, USUALLY WATER OR SALT SPRAY.

C. PITTING - LOCALIZED CORROSION WHICH TAKES THE FORM OF CAVITIES AT THE SURFACE OF METAL.

D. INTERGRANULAR - ATTACK WHICH OCCURS ALONG GRAIN BOUNDARIES OF SOME ALLOYS UNDER SPECIFIC CONDITION, USUALLY CAUSED BY IMPROPER HEAT TREATMENT.

E. EXFOLIATION - SEPARATION OF A METAL IN FLAKES OR LAYERS; ADVANCED STAGE OF INTERGRANULAR CORROSION.

F. CREVICE/CONCENTRATION CELL - A TYPE OF PITTING, WHICH DEPENDS ON DIFFERENCES IN CONCENTRATION OF THE ELECTROLYTE OR ACTIVE METAL AT THE ANODE AND CATHODE.

G. METAL ION CONCENTRATION - STAGNANT ELECTROLYTES UNDER LAYING SURFACES WILL NORMALLY HAVE A HIGH CONCENTRATION OF METAL IONS WHILE A LOW CONCENTRATION OF METAL IONS WILL EXIST ADJACENT TO THE CREVICE CREATED BY THE FAYING SURFACE.

H. OXYGEN CONCENTRATION CELL - ELECTROLYTE IN CONTACT WITH METAL SERVICES WILL NORMALLY CONTAIN DISSOLVED OXYGEN. AN OXYGEN CELL CAN DEVELOP AT ANY POINT WHERE THE OXYGEN IN THE AIR IS NOT ALLOWED TO DIFFUSE INTO THE SOLUTION, THERE BY CREATING A DIFFERENCE IN THE OXYGEN CONCENTRATION BETWEEN TWO POINTS.

I. ACTIVE-PASSIVE CELLS - METALS WHICH DEPEND ON A TIGHTLY ADHERING PASSIVE FILM, SUCH AS THE OXIDE FILM ON CORROSION RESISTANT STEEL, ARE PRONE TO RAPID CORROSIVE ATTACK BY ACTIVE-PASSIVE CELLS. THE CORROSIVE ACTION USUALLY STARTS WITH A DEPOSIT OF DIRT OR SALT WHICH CREATES AN OXYGEN CONCENTRATION CELL.

J. STRESS - (CORROSION CRACKING) A PROCESS REQUIRING THE COMBINED ACTION OF CORROSION AND SUSTAINED TENSILE STRESS.

K. FILIFORM - METALS COATED WITH ORGANIC SUBSTANCES, SUCH AS PAINT MAY UNDERGO CORROSION RESULTING IN NUMEROUS MEANDERING FILAMENTS. TAKES PLACE IN AREAS OF HIGH HUMIDITY, RESULTING IN NUMEROUS MEANDERING THREADLIKE FILAMENTS OR CORROSION.

L. FRETTING - DEVELOPS WHEN TWO HEAVILY LOADED SURFACES IN CONTACT WITH EACH OTHER ARE SUBJECT TO SLIGHT VIBRATION OR MOTION.

124.3 STATE THE BASIC THEORY OF CORROSION REMOVAL. (REF A)

BY THE MILDEST MEANS POSSIBLE.

124.4 STATE THE PROCEDURES USED TO WASH AIRCRAFT. (REF A)

WHEN WASHING AN AIRCRAFT, GO FROM INSIDE OUT AND BOTTOM TO TOP. PROPER AND FREQUENT CLEANING IS THE MOST IMPORTANT PART OF A CORROSION CONTROL PROGRAM. FREQUENCY OF CLEANING AND RELATED TREATMENT WILL DEPEND ON TYPE OF AIRCRAFT AND LOCAL CONDITIONS.

124.5 EXPLAIN NONMETALLIC DETERIORATION AS IT APPLIES TO THE FOLLOWING MATERIALS. (REF B)

A. ENCAP SEALANTS AND CONFORMAL COATINGS - BECAUSE THOSE MATERIALS ARE ORGANIC THEY ARE SUSCEPTIBLE TO MOISTURE, VARYING TEMPERATURE, AND FUNGUS. MOISTURE ACCUMULATES WHEN INCORRECT REPAIRS PROCEDURES CAUSE IMPERFECTIONS AND BUBBLES, OR WHEN THE COATING ARE APPLIED TO THICK.

B. POTTING COMPOUNDS - PROBLEMS OCCUR WHEN POTTING COMPOUNDS ARE CURED TO FAST, NOT MIXED PROPERLY, OR THE SURFACE IS NOR CLEANED.

C. RESIN SURFACES - OVER CLEANING WITH ABRASIVE MATERIALS MAY DAMAGE THE RESIN SURFACE. HIGH TEMPERATURE CAUSED BY THE BURNING OF A CIRCUIT MAY CHAR THE LAMINATE SURFACE AND INCREASE MOISTURE INTRUSION.

D. RUBBERS AND ELASTOMERS - NATURAL RUBBERS, SILICONE RUBBER, AND POLYURETHANE ARE NORMALLY SUSPTIBLE TO ATTACK BY FUNGAL, MICROBES, OZONE AN ULTRA VIOLET LIGHT.

E. PRESSURE SENSITIVE TAPES - PROBLEMS ARISE WITH CLOTH OR PAPER BASED TAPES. THESE MATERIALS ABSORB MOISTURE AND SUPPORT FUNGAL ATTACK. SOME TAPE DETERIORATE AND OUTGAS, EMITTING AN ACID THAT IS CORROSIVE TO METALS.

F. LUBRICANTS - USED IN SOME ELECTRONIC EQUIPMENT AND ARE CAPABLE OF MINIMIZING MOISTURE INTRUSION AND CORROSION ATTACK.
124.6 EXPLAIN INCOMPATIBILITY OF NONMETALLIC AND GIVE THREE EXAMPLES OF COMMON NONMETALLIC INCOMPATIBILITY. (REF B)

INCAPABILITY ON MATERIALS CAN CAUSE DETERIORATION OF THE NON-METALLIC SUBSTANCES. THIS MAY RESULT IN THE RELEASE OF CHEMICALS OR GASES THAT REACT WITH OTHER CIRCUIT COMPONENTS.
1) COMPOSITES - SOME ENCAPSULANT, CONFORAML COATINGS AND ACRYLIC PLASTIC SOFTEN OR DISSOLVES WHEN THEY COME IN CONTACT WITH CLEANING SOLVENTS.
2) SOME COMMERCIAL CONFORMAL COATING STRIPPERS CONTAIN ACIDS THAT ATTACK PCB LAMINANTS AND DISCOLOR OR CORRODE COPPER.
3) DEGRADATION OF (PVC) GIVES OFF ACID FUMES THAT ARE CORROSIVE TO MOST MATERIALS USED IN AVIONICS.

124.7 LIST THE FOUR ADVANTAGES OF SUCCESSFUL AVIONIC CLEANING AND CORROSION PREVENTION/CONTROL PROGRAM. (REF C)

1. REDUCE MAINTENANCE TIME SPENT REPAIRING CORROSION DAMAGE.

2. REDUCE MAINTENANCE ACTIONS CAUSED BY CORROSION

3. INCREASE AVIONICS SYSTEMS RELIABILITY, SENSITIVITY AND OUTPUT POWER

4. REDUCE PHANTOM GRIPES CAUSED BY DIRT, CORROSION AND MOISTURE IN CONNECTORS, PLUGS AND RECEPTACLES.

124.8 STATE THE TRAINING AND QUALIFICATION REQUIREMENT FOR AVIONICS PERSONNEL RESPONSIBLE FOR CORROSION PREVENTIVE MAINTENANCE AND TREATMENT. (REF B)

"A" SCHOOL OR NAMTRAGRUDET FOR CORROSION CONTROL

124.9 DESCRIBE THE NATURE AND APPEARANCE OF CORROSION PRODUCTS ON THE FOLLOWING METALS AND HOW THEY ARE PROTECTED. (REF B)

A. IRON AND STEEL - RUSTING (REDDISH COLORED IRON RUST)

B. CORROSION RESISTANT STEEL/STAINLESS STEEL - ROUGH SURFACES, SOMETIMES RED, BROWN OR FLACK STAIN.

C. ALUMINUM - ROUGH AND FROSTED, WHITE OR GRAY POWDER, FUNGUS

D. MAGNESIUM - WHITE OR GRAY POWDER, SNOW-LIKE MOUNDS

E. COPPER - BLUE OR BLUE-GREEN POWDERY DEPOSIT, TANISH TO GRAY-GREEN COLOR.

F. CADMIUM - WHITE POWDERY PRODUCTS, WHITE TO BROWN TO BLACK MOTTLING.

G. SILVER - TARNISHING, BROWN TO BLACK FILM

H. SILVER PLATED COPPER/RED PLAQUE - BROWN TO BLACK FILM

I. GOLD AND GOLD PLATING - DARKENING OF REFLECTIVE SURFACES

J. GOLD BONDED TO ALUMINUM - DARKENING OF REFLECTIVE SURFACES

K. TIN - WHISKER-LIKE DEPOSITS

L. BLACK PLAQUE - BLACK SUBSTANCE THAT FORMS IN THE COOLANT OF HIGH POWER RADARS

M. NICKEL - THREAD-LIKE FILAMENTS, GREEN POWDERY DEPOSITS