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27 Cards in this Set
- Front
- Back
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Define erosion?
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Erosion is the complex phenomenom resulting from extreme chemical reactions under extreme temperatures and pressure which cause an enlarging or damaging to the bore due to firing
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What is the major cause of gun tube wear?
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Erosion
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What are the first indications of erosion?
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hairline cracks or a checkering efect of the base metal near the origin of the bore
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How is erosion detected?
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By using the M3 borescope device
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When is the cannon tube condemned by erosion?
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When erosion at any location exceeds 5mm of wear in depth into the base metal.
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What is used to measure erosion?
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The M12 erosion gage
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What is the purpose of the chrome lining?
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The purpose of the chrome lining is to extend the life of the gune tube by delaying erosion of the gun tube base metal
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Define eccentricity?
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This is the tendancy of the gun tube to widen or "bell mouth"near the muzzle
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What advers effects does eccentricity have of ballistic perormance?
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No data to date has indicated any adverse effects, but you must be aware of that this condition exist.
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How do you verify that you have an eccentric gun tube?
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1. Insert a Muzzl Boresight Device(MBD) in to the muzzle of the tank. Check the MBD, the cone should seat all the way around the gun tube.
2. Measure the distance between the witness marks at the 12 o'clock and 6 o'clock positions using a ruler, then compare those with the measurements between the 3 and 9 o'clock measurements. |
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When do you condemn a gun tube for eccentricity?
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If the muzzle shows evidence of an out of round condition that prevents proper boresighting
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Define cracking?
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Chararcteristics of cracking include feathered edges running in an irregular line with varying width and depth, may be present on the interior or exterior of the gun.
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When is the gun tube condemned for cracking on the interior surfaces?
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If the crack exceeds 0.125 inch/ 1/8 inch on the interior surface
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Wen does cracking condemn the exterior of the gune tube?
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The gun tube is condemned if cracks exceed 0.25 inch/ 1/4 inch on the exterior surface of the gun tube.
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Define pitting?
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Pitting is the result of corrosion on the surfaces of the gun tube.
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What condemns the gun tube in zone 1 for pitting?
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0.03 inches in depth or 20% of the total surface area.
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What condemns the gun tube in zone 2 for pitting?
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0.05 inches in depth or 20% of the total surface area.
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What condemns zone 3 for pitting?
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Ignore pitting in zone 3, zone 3 is condemned for erosion
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What condemns the gun tube for pitting on the external unpainted surfaces?
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.02 inches in depth or 80% of the total surface area
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What condemns the gune tube for pitting on the painted surfaces?
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.04 inches in depth or 80% of the total surface area.
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What is borescope?
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An interior 360 degree visual inspection of the gun tube from the chamber to the muzzle.
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What do you us to conduct a borescope?
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M3 Borescope device
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What is the frequency of inspection of the M256A1?
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1. Every 150 EFC rds after the first f300EFC have been fired.
2. Within 180 days prior to firing 3. When trouble shooting indicates you should 4. Anytime a cannon tube is installed, even if new. 5. If you are uncertain whether or not a tube has been inspected |
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What is the purpose of the Recoil System Excercise?
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Moving of the piston in the gun cradle to reestablish a fluid film between the packing seals and sliding surfaces.
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Hydrospring recoil systems must be excercised and inspected how often?
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Every 180 Days
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What are the three methods to conduct a recoil excercise?
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1. M3 oil pump
2. Gun mount excercise kit 3. Firing one round(least Prefered) |
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How far do you recoil the hydrospring recoil system?
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back and forth 3 times, 6-8 inches
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