7.18A Flashcards
What two defects do you inspect for
Corrosion
Metal fatigue
What do you do if a component has inter-granular corrosion
Replace
What is metal fatigue
Weakening of a metal part under repeated cycles of stress
How is metal fatigue accelerated
By corrosion
If you need further inspection of metal fatigue what do you do
Get NDT in
What should you do if you find articles
Examine to see if they are loose articles or indicative of structural failure
When inspecting/probing a joint what should you use
Non metallic instrument
What endoscope should you use in areas that might combust
2nd type/ cold light source
What is the definition of damage
Any permanent deformation/alteration of the cross section of structural component
What are the damage classification
Allowable
Non allowable
Non repairable
What does allowable damage mean
Slight/little significance
Does not mean repair is unnecessary
What does non allowable mean
Exceeds allowable damage limits - repair it
What does non repairable mean
Damage to structural repair components that cannot be repaired
Replacement as repair is not practical or economical
When should you remove corrosion
Most corrosion should be removed
What chapter tells you about limits of corrosion
Chapter 51 or SRM
What else should you do when removing corrosion
Make a note of how much corrosion you have removed
When inspecting painted surface corrosion what are the signs of it
Scaly or blasted surface
Change of colour
Blisters in paint
Dull darkened pitts in metallic surface
What colours can corrosion show up as
White, grey, red dust particles
How should you remove light corrosion
Abrasive cloths or pads
What wire brushes should you use to get rid of corrosion
Stainless steel or aluminium oxide coated brushes
How should you remove hard corrosion
Grinding motor
What are the disadvantages of a grinding motor to get rid of corrosion
Not suitable for aluminium alloys
Can cause high temps so changes mechanical properties
When should you use rotary files and what is it suitable for
When corrosion is heavy
Suitable for aluminium and steel alloys
When should you use abrasive blasting
On filiform corrosion
How can you ensure that all the corrosion has been removed
By using a x10 magnifier
Getting NDT IN
How do aluminium alloy corrosion present itself
White deposits
Etching, pitting and roughness
What brushes can’t you use on aluminium alloy and what should you use
Carbon steel and steel wool brushes
Use stainless steel
How does corrosion on carbon steel present itself
Red rust
How does corrosion on stainless steel/nickel chromium present itself
Pitting usually a black colour
How does titanium alloy corrosion present itself
Black or white colour
How do you remove corrosion on titanium and what do you need to be careful off
Gental corrosion removal because small chips that can easily ignite
How would you put out a titanium fire
Sand or a non water based extinguisher
How do you remove corrosion from cadmium plated parts
Dampened abrasive pad
How do you dispose of cadmium plates corrosion
By instructions from local authorities
What does SAA stand for
Sulphuric acid anodising
What does CAA stand for
Chromic acid
What does CCC stand for
chemical conversion coating
What paint finish does airbus follow
3 phases paint system
What paint finish does Boeing follow
2 phase paint finishing system
What should you do if you suspect a corrosion under paint
Make a small test area
What are the three types of surface protection repairs
Fixing
Partial/total renewel
Basic renewal
What is the main example of a corrosion protective paints
Electrically conductive paint
What areas need priming for electrically conductive paint
All plastic components of outer skin expect the antenna
What else need to be covered with electrically conductive paint
Minimum of 75% of all countersinks
What is the most common water repellent fluid and where can’t you use it
Dinitrol
Oil based so no oxygen systems as will explode
