General: Cleaning and Corrosion Control 🔊

Question 1

What are the five common forms of corrosion?

Answer 1

(F-DISS) Fretting, dissimilar metal, intergranular, surface, and stress

Question 2

Name at least three factors that influence corrosion.

Answer 2

Temperature, type of metal, availability of electrolytes and dissimilar metals, condition of protective coating

Question 3

What are the two general conditions that may cause stress corrosion cracking?

Answer 3

Sustained tensile stress and corrosive environment

Question 4

What is the cause of fretting corrosion?

Answer 4

When two mating surfaces which are normally at rest with respect to each other are subject to relative motion. Characterized by pitting of the surface and the generation of large quantities of fine debris. (smoking or mudding rivets)

Question 5

What is the principal cause of filiform corrosion?

Answer 5

Surfaces that have not had the proper chemical treatment before painting

Question 6

Where is intergranular corrosion most likely to occur?

Answer 6

Along the grain boundaries of extruded material

Question 7

What is another name for dissimilar metal corrosion?

Answer 7

Galvanic corrosion

Question 8

What are the factors which affect the type (form) of corrosion?

Answer 8

Atmospheric conditions, size and shape of the metal, the type of metal, and the corrosion producing agents present

Question 9

What methods are used for removing rust from aircraft materials?

Answer 9

Abrasive paper and compounds, small power buffers and buffing compounds, hand wire brushes, and steel wool (except on highly stressed steel surfaces like oleo struts)

Question 10

What is an acceptable method for removing surface corrosion from titanium?

Answer 10

Stainless steel brush, aluminum oxide sandpaper, scotch brite, abrasive blasting using glass bead, or hand polishing using aluminum polish and a soft cotton cloth

Question 11

What specific operations are part of corrosion preventative maintenance?

Answer 11

Adequate cleaning, periodic lubrication, detailed inspection, prompt corrosion treatment, touch up paint, sealing, use of protective covers, and daily wipe down of exposed critical areas

Question 12

Name the steps for corrosion removal.

Answer 12

Clean and strip the corroded area, remove as much corrosion as possible, neutralize any residual material remaining in pits and crevices, and restore protective surface films and paint.

Question 13

What tools are approved for cleaning corroded anodized surfaces?

Answer 13

Fiber bristle brushes, aluminum wool, and aluminum wire brushes

Question 14

What is used to keep corrosion from forming on aluminum alloy?

Answer 14

Oxide coating or aluminum cladding

Question 15

What can be used to repair the anodized surface of an aluminum alloy part?

Answer 15

Alodine or other chemical conversion coatings

Question 16

What products should be used to clean an aircraft engine?

Answer 16

A fine spray of kerosene or solvent

Question 17

What should be used to clean grease, fuel, or oil from aircraft rubber tires?

Answer 17

Soap and water

Question 18

Why should only recommended cleaners be used on aircraft fabric and plastics?

Answer 18

They cause less degradation of the materials

Question 19

Name 5 areas of an aircraft that are more prone to corrosion.

Answer 19

Battery compartments, bilge areas, wheel wells and landing gear, flap recesses, lavatory, galley, and other areas where water might be entrapped

Question 20

What form of corrosion can be found in battery compartments?

Answer 20

Direct chemical corrosion

Question 21

Why are piano-type hinges prime locations for corrosion?

Answer 21

They use dissimilar metals (steel pins and aluminum hinges) and tend to trap contaminants between them

Question 22

What is used to neutralize a lead-acid battery electrolyte?

Answer 22

A solution of baking soda and water

Question 23

What is the difference between “wet wash” and “dry wash” aircraft cleaning?

Answer 23

Wet wash (water and an agent) removes oil, grease, carbon deposits, and soils, except for corrosion and oxide films. Dry wash (cloth or compressed air) removes film, dust, and small accumulations of dirt.

Question 24

What are types of light duty and heavy duty aircraft cleaning agents?

Answer 24

Light duty are soap and synthetic detergents. Heavy duty are solvents and emulsion type cleaners.

Question 25

What would you do before cleaning a wind screen?

Answer 25

Wet the surface to prevent scratching

Question 26

What does filiform corrosion look like and where can it be found?

Answer 26

Thread or worm like puffiness of paint. It is found between the metal’s surface and the protective coating.

Question 27

How is the inside of structural tubing prevented from corroding?

Answer 27

Coated in hot linseed oil