Cleaning and Corrosion Prevention and Control - 1-1-691 Flashcards
In sea water the corrosion reaction is accelerated by a factor of __ or more.
1,000
__ or __ results from a direct chemical attack on a metal surface and involves only the metal surface.
Uniform surface corrosion, etching
__ occurs when different metals are in contact with each other and an electrolyte, such as salt water.
Galvanic corrosion
The most common corrosion on aluminum and magnesium alloys is called __.
pitting
__ is an attack on the grain boundaries of the metal.
Intergranular corrosion
__, is an advanced form of intergranular corrosion where the surface grains of a metal are lifted up by the force of expanding corrosion products occurring at the grain boundaries.
Exfoliation
__ corrosion occurs when the electrolyte has a different concentration from one area to another.
Crevice
__, is the intergranular or transgranular cracking of a metal caused by the combined effects of constant tensile stress (internal or applied) and corrosion.
Stress corrosion cracking
7075-T6 aluminum alloy can fail by stress corrosion cracking when a stress which is only __ of its rated strength is present across the thickness of its metal grains or the short transverse grain direction.
10%
__ is the cracking of metals caused by the combined effects of cyclic stress and corrosion and is very similar to stress corrosion cracking.
Corrosion fatigue
__, is a special form of oxygen concentration cell
corrosion or crevice corrosion which occurs on metal surfaces having an organic coating system.
Filiform corrosion
Filiform occurs when the relative humidity
of the air is between __ and __, and when the surface is slightly acidic.
78%, 90%
Filiform corrosion can be prevented by storing equipment and aircraft in an environment with a relative humidity below __.
70%
__ is a special form of concentration cell corrosion which occurs in combination with surface wear.
Fretting Corrosion
Corrosion in the absence of water that can occur at high temperatures, such as those found in turbine engine compressors and hot sections.
High Temperature Oxidation (Hot Corrosion)
__ are the lightest structural metals used for aircraft and missile airframes.
Magnesium alloys
Effective sacrificial coatings that prevent corrosion on ferrous alloys are __ or __
cadmium plating, low hydrogen embrittling zinc nickel
Titanium and titanium alloys have many uses in aircraft and missiles at temperatures up to __.
1,000° F (540° C)
Growth of molds and bacteria is also inhibited by temperatures above __.
104° F (40° C)
Normal sea winds carry from __ to __ pounds of sea salt per cubic mile of air.
10, 100
During sandstorms small sand particles are often blown as high as __ feet.
10,000
Ideal growth conditions for most fungi
and bacteria are temperatures of __ and relative humidities of __ .
+68° to +104° F (+20° to +40° C), 85 to 100%.
If using closed-loop water recycling systems for washing aircraft, water shall meet the following requirements and be tested every __ days
30
All locations within __ miles of salt water are considered severe and require __ day wash.
1.25, 30
Clear water rinsing shall not be accomplished outside
when the temperature is at __ or below.
40° F (4° C)
All aircraft stationed within 1.25 miles (2 km) of salt
water require a Clear Water Rinse at least once every __ unless washed first.
15 days
Aircraft making two or more take-offs and or/landings, including touch-and-go landings, when the runway approach is under __ require a CWR after the aircraft completes the last flight of the day.
3,000 feet and over salt water
Any aircraft (primarily transient aircraft) performing only a single takeoff and/or landing requiring low-level flight (below 3,000 feet) over salt water in a single day are excluded from CWR unless there are \_\_ or more occurrences within a 30 day period.
ten
Search, rescue, and recovery missions or any other low-level flight operations that require aircraft to operate over salt water at altitudes under 3,000 feet require a CWR after __.
the aircraft completes the last flight of the day
To be most effective, cleaning materials are applied full strength with no pre-rinsing of the surface, allowed to dwell __ minutes
5 to 15
The dwell time for all types of P-D-680 should be held
to a minimum (__)
less than 15 minutes
Steam cleaning __ be used on aircraft and missiles at all levels (Organizational/Unit, Intermediate, or Depot) of maintenance.
shall not
Use of hot water (__) for rinsing during aircraft washing operations is strongly recommended as it provides much more efficient rinsing and is known to reduce man-hours for aircraft washing operations by approximately __.
120° to 140° F/49° to 60° C, 20%
Cleaning solution for exterior painted/unpainted/interior surfaces/most exterior surfaces
MIL-PRF-87937
Cleaning solution for control cables:
PRF-680
Cleaning solution for landing gear exposed piston:
83282
Cleaning solution for doors, linkages, cylinders:
680
Use only __° flat fan spray nozzles. Ensure that the nozzle stand-off distance to the surface is always at least __ inches and never less.
40, 12
What PSI for portable foam generating cleaning units?
30 to 70
Dwell time for portable foam generating cleaning units?
1 minute
During scheduled or unscheduled maintenance actions on aircraft, missiles, or equipment and their components, the area involved as well as those within __ inches (__ inches on each side) of the repair or treatment area shall be visually inspected for corrosion.
36, 18
If corrosion is suspected, examine the area with a __X
magnifying glass and flashlight.
10
Light corrosion:
1 mil (.001)
Moderate corrosion:
10 mil (.010)
First remove all corrosion visible through a __X magnifying glass, then removing an additional __ to ensure that all deposits have been eliminated.
10, two mils (0.0020 inch)
Do not use brushes with a bristle wire gauge or diameter above __
0.010 inch
Keep the sanding disc tilted to approximately a __ degree angle so that only one side of the disc is in contact with the metal surface.
10
Generally, the coverage rate should be about __. (Sanding)
two square feet per minute
Do not use flap brushes downto within __ of core.
2 inches
Do not use __ to remove corrosion from installed fasteners.
rotary files
Inspect nozzles periodically for wear and discard them when the orifice is worn to a diameter which is __ greater than the diameter when new.
50%
Blast media used on aircraft and aircraft components shall be tested for contamination or purged every hours of equipment operation
80
Sheet metal, __ or thinner, shall not be blasted.
0.0625 inch (16 gauge, U.S. Standard)
Blasting media stream angle?
30° to 40°
Nozzle distance from surface when blasting?
2-6 inches
If corrosion has not been removed in a total blasting time of __ seconds on any one specific area, other mechanical methods of removal should be utilized.
60
Dwell time for aluminum conversion coating?
1 - 5 minutes
Dwell time for magnesium conversion coating?
1 - 3 minutes
The area roto-peened shall not be larger than __ inches.
3 x 4
When using a sealing gun, the nozzle tip must be pointed into the seam and maintained at a __ degree angle to the line of travel
45
The application life of a sealant is the length of time that a mixed sealing compound remains usable at __ and __% relative humidity (RH).
77° F (25° C), 50
Do not apply heat to sealants until __ minutes minimum have elapsed at ambient (room) temperature
after application to allow the contained solvents to flash off.
30
Always __ to avoid contaminating the solvent supply.
pour solvent on the cloth
The dry film thickness (DFT) of spray sealant coatings shall be in the range of __.
3 to 5 mils (0.003 to 0.005 in)
For permanent structure, all faying surfaces, seams, and lap joints outside of fuel wet and high temperature
areas shall be protected with __
MIL-PRF-81733
If, during normal maintenance, it becomes necessary to remove and replace components (wing planks, skin, spar caps, fasteners, fittings, etc.,) they shall be __ when reinstalled, even if they were not sealed originally.
sealed
When the thickness of metal is reduced by more than 15 mils (0.015 in) in the removal of corrosion damage, fill the depression with __
MIL-PRF-81733
Sealants shall not be stored in areas where the temperature exceeds __.
80° F (27° C)
If a sealant has exceeded its original shelf life, then it shall not be used until __.
the update testing has been performed
Sealants may be extended __ of their original shelf life after passing the required tests.
one-half
Do not use __ to clean installed
steel control cables.
metallic wools
Natural and synthetic rubber shall not be __.
painted or oiled
Engines which are contaminated with small amounts of sea water entering the intake shall be cleaned using __
MIL-PRF-85704
Cleaning and Corrosion Prevention and Control, Aerospace and Non-Aerospace Equipment
1-1-691
Cleaning with compressed air can create airborne particles that may enter eyes or penetrate skin. Pressure shall not exceed __.
30 PSIG
__ materials are specially formulated
to minimize corrosion of aircraft turbine engines.
MIL-PRF-85704
__ shall not be used to clean bearings
Aqueous parts washers
__ shall not be applied with atomizing spray equipment.
Solvents
