Cleaning & Corrosion Flashcards
(46 cards)
What is meant by metal corrosion?
The deterioration of the metal by chemical or electrochemical attack
What material forms a greenish film when corroded?
Copper and Copper Alloys
What are two general classifications of corrosion?
- Direct chemical attack
- Electrochemical attack
Name three common agents that cause direct chemical attack on aircraft metal structure:
- Spilled battery acid
- Residual flux deposits
- Entrapped caustic cleaning solutions
What is meant by an electrochemical attack on aluminum alloy?
A natural attack occurrence that attacks metal converting back to a metallic compound in which 4 conditions must exist.
Anode
Cathode
Electrolyte
Electrical contact between anode and cathode
What type of corrosion is most common on aircraft structures?
Surface Corrosion
How does surface corrosion appear on the surface of an alloy?
As general roughening, etching, or pitting on the surface of a metal
Does all corrosion appear on the surface of an alloy?
No, sometimes corrosion spreads under the surface coating
What is meant by dissimilar metal corrosion?
Contact between dissimilar metal parts in the presence of a conductor
How may intergranular corrosion be detected?
Ultrasound
Eddy Current
X-ray
Where does fretting corrosion generally occur?
Between two mating surfaces
Name six operations which are good corrosion-preventative measures:
- Adequate cleaning
- Periodic lubrication
- Detailed inspection
- Prompt treatment of corrosion
- Daily wipe down
- Sealing of aircraft against water
How often should aircraft be checked for corrosion?
During routine maintenance inspections. Seaplanes must be checked daily.
Mild zones: Every 90 days
Moderate zones: Every 45 days
Severe zones: Every 15 days
Are exhaust gases considered to be corrosive?
Yes
Both jet and reciprocating engine exhaust deposits are very corrosive
How is corrosion around battery boxes minimized?
Regular cleaning and neutralization of acid deposits
How are the bilge areas of a seaplane protected from corrosion?
•Chemical conversion coating applied to the surfaces of the sheet material •Sealants are installed at the lap joints •Interior compartments are painted
What is done to prevent water entrapment in aircraft?
Drains are installed in all areas where water may collect
Where would corrosion most likely occur on an aircraft skin?
•Edges
•Areas around fasteners
•Cracked, chipped, or areas with missing paint
What is the proper treatment for a control cable found to have internal corrosion?
Replace cables that have internal corrosion
Name nine steps for complete corrosion preventative maintenance:
- Keep drain holes free from obstructions
- Adequate cleaning
- Thorough periodic lube
- Drain fuel cell sumps
- Maximum use of protective covers while parked…….
I doubt they will ask us all of this i’m not writing them all out lol
What type of paint stripper is recommended for aircraft structure?
Water soluble stripper can be used for most applications
How long should paint remover remain on the surface before it is washed off?
Between 10 minutes to several hours depending on the temperature, humidity, and the condition of the paint.
If steel rust is allowed to remain on the surface, will it prevent further attack?
It’s presence actually promotes additional attack by attracting moisture from the air and acting as a catalyst for corrosion
What is the most practical way of removing corrosion products from steel?
By mechanical means and restoring corrosion preventive coatings
