Module 7.18 Flashcards
What is the definition of damage?
Change in CSA or permanent distortion
What is the definition of a defect?
Event or condition that reduces serviceability
What must be done before any repair?
- Find extent
- Material used
- Type of repair required
Where should the assessment of damage begin?
Inspection of riveted joints and an inspection of corosion
What are the 3 damage categories?
- Allowable
- Non allowable
- Non repairable
What defines abrasion?
Damage as a result of scuffing, rubbing or scraping
What defines corrosion?
Change in CSA due to electro chemical action
What defines a crack?
Partial or full break in the material that cause CSA damage
What defines crease?
Area that is depressed or folded back
What defines delamination?
Disband that occur between adjacent layers
What defines a dent?
Area pushed in from its centre length is the largest distance
What defines a disband?
Separation of material
What defines gauge?
CSA change due to sharp object gives a continuous sharp/smooth groove
What defines a hole?
Complete penetration
What defines a nick?
Local gouge with sharp edges
What defines a puncture?
Full penetration with no regular shape
What defines a scratch?
A line of damage, change in CSA (Cross Sectional Area)
Prior to inspection what should be done?
Open all required panels and structure throughly cleaned
When opening the panels and cowlings what should be looked for?
Any oil or fluid leaks
What can be produced to ensure that no areas are overlooked or forgotten?
A checklist
What inspection methods are often used?
Non Destructive Inspection (NDI)
What must be determined from the inspection?
What is the best repair or is replacing necessary
What visual aids can be used to help the inspection process?
Torches, mirrors, magnifying glass
How can internal structure and components be inspected?
Boroscope
What can corrosion left alone lead to?
New corrosion to form
What can corrosion look like on a painted surface?
Scaly surface, change of colour, blisters in the paint
When would damage be assessed?
After all corrosion is removed
How is paint removed in small areas and large areas?
Small - Mechanical
Large - Chemical
What must be done to affected fasteners?
Removal
What magnifying glass should be used to check for corrosion removal?
10x
What mechanical methods are not suitable for aluminium?
Wire brushing, grinding
Where can’t you abrasive blast?
Internal areas
What doesn’t rust do, that passive films do?
Protect metal underneath
What does the presence of rust act as?
A catalyst
What is the most. common chemical method of rust removal?
Phosphoric acid
What does phosphoric acid to remove rust?
Makes it water soluble
What colour does corrosion on CRES + nickel chromium appear as?
Black
How is CRES + nickel chromium corrosion removed?
Phosphoric acid
How can titanium surfaces be cleaned?
By hand with aluminium polish
What is the purpose of pre treating metal?
- Increase corrosion resistance
- Better adhesion surface
What is anodising?
Layer of oxide produced to act a a barrier
What affects film thickness?
Voltage and duration
What is CAA treatment?
Chromic acid anodising uses chromic acid
What is Eloxadising?
Electric oxides aluminium with sulphuric acid
What annoying process do airbus use?
Sulphuric acid anodising
What properties do Eloxation layers have?
Ceramic, so not elastic
Where is anodising used?
- Integrally milled structural parts
- Bonded surfaces
- On the outer skin
Where are phosphate coatings used?
On steel parts
What are the 3 main types of phosphate coatings?
- Manganese
- Iron
- Zinc
When must chemical conversion not be used?
Components subjected to an operating temp more than 70 degrees C
Define paint finishes?
All coatings manually painted or sprayed on
What are the 2 main reasons for paint finishes?
- Decorative finishes
- Cabin protection
What 3 layers do Airbus use?
- Wash primer
- Paint primer
- Coating lacquer
What 2 layers do Boeing use?
- Primer
- Top coat
What occurs before priming on Boeing?
Pre-treatment: CCC (Chemical Conversion Coating)
What occurs before priming on Airbus?
Pre-treatment: CCC (Chemical Conversion Coating) or CCA (Chromic Acid Anodised)
What occurs before priming on both Boeing and Airbus?
Pre-treatment: CCC (Chemical Conversion Coating)
What parts/components require a conductive paint coating?
Plastic components, i.e. radome
To achieve conductivity how many countersinks must be painted with conductive paint?
Minimum 75%
Where must antistatic not be applied?
Antennae covers
When would water displacing inhibitors be used?
In areas that do not permit corrosion removal
When is FCR primer not recommended?
Higher than 75% humidity and below 15 degrees C
What is a jig?
A device that allows manufacture repair or rigging to high dimensional accuracy
When installing a rivet hart is the formed end called?
Shop end / tail end
Cracks in the head are permitted to limits in what alloy of rivets?
2017, 2024
Friction lock rivets cannot be replaced by what?
Solid shank rivets of the same size
Disadvantage of a mechanical lock could be?
Too short for application
What is the most common removal method of hi-locks?
Allen key and mole grips
What are 2 types of sealants?
- Silicone
- Non silicone
Where would silicon sealants be used?
Heat resistance is required
What colour are silicon sealants?
White, red, grey
How are class E and F sealants applied?
Sprayed on
What is the application time?
Time after thawing that the sealant can be applied
What is tack free time?
Sufficient curing that it won’t transfer to a finger
What is cure time?
Cured firmly enough that it can be handled without damage
Sealant removal tools are made of what?
Hard wood or metal no harder than 2024 T3
Where are fillet seals applied?
Edges of joints
Injection seals are used to fill what?
Channels
Where would faying seals be used?
Layer of seal between 2 fastened surfaces
What is the seal plane?
Structural boundary where leak may occur
