Comprehensive Review of Basic Math, Physics, and Aircraft Parts for Technical Exams

What is the total piston displacement of an engine?

The total volume of all the cylinders, dependent on the compression ratio, and the volume displaced by all the pistons during one revolution of the crankshaft.

What is the surface area of a cube with a side length of 7.25 inches?

315.371 square inches.

How do you calculate the grip length of a bolt with an overall length of 1-1/2 inches, shank length of 1-3/16 inches, and threaded portion length of 5/8 inch?

Grip length = Overall length - (Shank length + Threaded portion length) = 1.5 - (1.1875 + 0.625) = 0.6875 inch.

What is the cost of a part if the selling price is $145.60 and the profit is 12 percent?

Cost = Selling price / (1 + Profit margin) = $145.60 / 1.12 = $130.00.

Which fraction is equal to 0.0250?

1/40.

What is the approximate fractional size of a drill bit for a hole of 0.17187?

11/64.

If an engine develops 108 horsepower at 87 percent power, what horsepower would it develop at 65 percent power?

81 horsepower.

What is the fractional equivalent for a 0.0625 inch thick sheet of aluminum?

1/16.

What is the approximate piston displacement of a four-cylinder engine with a cylinder bore of 3.78 inches and depth of 8.5 inches?

235 cubic inches.

What is the square root of 1,824?

42.707.

What is 1.21875 in scientific notation?

1.21875 = 1.21875 x 10^0.

What is the square root of 3,722.1835?

61.0.

What is the cube of 64?

262,144.

Convert the binary number 00001111 to a whole number.

15

Which alternative answer is equal to 16,300 in scientific notation?

1.63 x 10^4.

What is the square root of 4 raised to the fifth power?

32

What size of sheet metal is required to fabricate a cylinder 20 inches long and 8 inches in diameter?

20 inches x 25-9/64 inches.

What is the decimal equivalent of a bend radius of 31/64?

0.4844.

Convert the number 7 to binary form.

111

What percent of 80 engines does 65 engines represent?

81 percent.

Express 7/8 as a percent.

87.5 percent.

What is the ratio of 10 feet to 30 inches?

1:3.

What is the square root of 124.9924?

11.18.

What is the horsepower being developed by an engine of 98 horsepower maximum running at 75 percent power?

73.5 horsepower.

What is the square root of 16 raised to the fourth power?

256

What percent of the maximum part life of 1100 hours has been achieved if the average life of 15 parts is 835.3 hours?

75.9 percent.

What is the diameter of a piece of round stock with a radius of 7/32?

0.4375.

How many cubic feet are within a rectangular-shaped fuel tank measuring 60 inches in length, 30 inches in width, and 12 inches in depth?

12.5 cubic feet.

What is the formula for calculating the compression ratio of a cylinder?

Compression ratio = Volume of cylinder / Piston displacement.

If a piston has a volume of 84 cubic inches and a displacement of 70 cubic inches, what is the compression ratio?

The compression ratio is 1.2:1.

What is the speed ratio of an input gear with 36 teeth meshed to a gear with 20 teeth?

The speed ratio is 1.8:1.

How many gallons of gasoline will an airplane need to travel 2,500 miles if it used 60 gallons for 750 miles?

It will need 200 gallons.

What is the result of 7 raised to the third power plus the square root of 39?

The result is approximately 343.24.

What is the value of 10 raised to the negative sixth power?

The value is 0.000001.

What is the piston displacement of a master cylinder with a 1.5-inch diameter bore and a 4-inch stroke?

The piston displacement is approximately 7.0686 cubic inches.

How many cubic feet are equal to 60 gallons of fuel?

8.0 cubic feet.

What is the current drawn by a 30-volt, 1/2 horsepower motor that is 85% efficient?

It draws approximately 14.3 amperes.

If an engine is turning 1,965 rpm at 65% power, what is its maximum rpm?

The maximum rpm is approximately 3,023.

Express 5/8 as a percent.

5/8 is equal to 62.5 percent.

What is the volume of a rectangular fuel tank measuring 37-1/2 inches in length, 14 inches in width, and 8-1/4 inches in depth?

The volume is approximately 4,331.25 cubic inches.

What force is exerted on a piston in a hydraulic cylinder with an area of 1.2 square inches and fluid pressure of 850 PSI?

The force exerted is 1,020 pounds.

Convert the binary number 1111 to decimal form.

The decimal equivalent is 15.

What is defined as a group of bits representing a complete piece of information?

A byte.

What power of 10 is equal to 1,000,000,000?

10 to the ninth power.

What is the ratio of a gasoline fuel load of 200 gallons to one of 1,680 pounds?

The ratio is 5:42.

Which of the following defects are not acceptable for metal lines?

Cracked flare, seams, and dents in the heel of a bend less than 20% of the diameter.

What is the speed of a spur gear with 42 teeth driven by a pinion gear with 14 teeth turning 420 RPM?

The speed of the spur gear is 140 RPM.

What is the equivalent of 3.47 x 10 to the negative fourth power in decimal form?

It is equal to 0.000347.

Which methods may be suitable to detect cracks open to the surface in aluminum forgings and castings?

Dye penetrant inspection, magnetic particle inspection, eddy current inspection, and ultrasonic inspection.

What should a part be cleaned with before dye penetrant inspection?

A volatile petroleum-base solvent.

Which tool is used to measure the clearance between a surface plate and a narrow surface for flatness?

Depth gauge.

How can a part be demagnetized after magnetic particle inspection?

By slowly moving the part out of an ac magnetic field of sufficient strength.

What tool is used to find the center of a shaft or cylindrical work?

Dial indicator.

What types of materials can liquid penetrant inspection methods be used on?

Porous plastics, ferrous metals, nonferrous metals, smooth primer-sealed wood, and non-porous plastics.

What should a mechanic be familiar with when evaluating a welded joint?

The parts, proportions, formation of a weld, welding technique, filler material, and temperature range used.

What is descriptive of the annealing process of steel?

Slow cooling; low strength.

What non-destructive testing method is used to determine the soundness of a bonded honeycomb repair?

Ultrasonic test.

Which non-destructive testing method requires little preparation and detects surface defects?

Eddy current inspection.

Under what condition must a fiber-type, self-locking nut not be used on an aircraft?

If the bolt is under tension loading.

What does a bolt with an X inside a triangle on the head signify?

It is classified as a NAS standard aircraft bolt.

Why is it good practice to normalize a part after welding?

To relieve internal stresses developed within the base metal.

What is the penetration requirement for a fillet weld as a percentage of base metal thickness?

25 to 50 percent.

What class fit are aircraft bolts usually manufactured with for the threads?

Class 2 fit for the threads.

What do torque values for tightening aircraft nuts and bolts relate to?

Clean, dry threads.

What metal is used in aircraft firewalls for its special short-time heat properties?

Chrome molybdenum alloy steel.

How should aircraft bolts be installed unless otherwise specified?

So that the bolthead is upward, or in a rearward direction.

What heat-treating operation changes the surface of the metal by introducing high carbide or nitride content?

Case hardening.

Which tool can determine piston pin out-of-round wear?

Dial indicator.

What is one method to demagnetize an aircraft part?

Subjecting it to a magnetizing force from alternating current that is gradually reduced in strength.

What is another method to demagnetize an aircraft part?

Subjecting it to a magnetizing force from a direct current that is alternately reversed in direction and gradually reduced in strength.

What is a telescopic gauge used for?

Measuring the diameter of holes, particularly small ones.

What is the purpose of demagnetizing an aircraft part?

To remove residual magnetism by subjecting it to a magnetizing force that is alternately reversed and gradually reduced.

What occurs when a mechanical force is repeatedly applied to metals at room temperature?

The metals become cold worked, strain or work hardened.

How is the locking feature of a fiber-type locknut obtained?

By making the threads in the fiber insert slightly smaller than those in the load-carrying section.

What is magnetic particle inspection primarily used to detect?

Flaws on or near the surface of materials.

What precision measuring tool should be used for measuring a hole approximately 1/4 inch in diameter?

A small-hole gauge or a micrometer.

What is the pattern for inclusion in magnetic particle inspection?

A fern-like pattern.

What does normalizing refer to in heat treating?

A process that applies to both aluminum alloys and iron-base metals.

Which aluminum alloy designation indicates no hardening or tempering treatment?

6061-O.

What characteristics does the testing medium used in magnetic particle inspection have?

High permeability and low retentivity.

What conditions allow self-locking nuts to be used on aircraft?

The bolt or nut must not be subject to rotation.

What effect does reheating heat-treated metal have?

It can significantly alter a metal's properties in the reheated area.

What is the most probable cause of unclear dye penetrant inspection indications?

The part was not correctly degaussed before the developer was applied.

What precision measuring tool is used for measuring crankpin and main bearing journals for out-of-round wear?

A dial gauge.

Which material cannot be heat treated repeatedly without harmful effects?

Unclad aluminum alloy in sheet form.

In the SAE number '4130', what does the first digit indicate?

The percentage of carbon in the alloy in hundredths of a percent.

How is the twist of a connecting rod checked?

By installing push-fit arbors in both ends and measuring between the arbor and parallel bars with a dial gauge.

What factors are essential knowledge for x-ray exposure?

Processing of the film, material thickness and density, exposure distance and angle, and film characteristics.

What type of corrosion may attack grain boundaries of aluminum alloys due to improper heat treatment?

Intergranular corrosion.

Under what condition is a part identified as having a fatigue crack in magnetic particle inspection?

When the discontinuity is found in a highly stressed area of the part.

What type of flaw in magnetic particle inspection causes a large disruption in the magnetic field?

A flaw that is perpendicular to the magnetic field flux lines.

What is the maximum distance from a weld where no oxide should be formed on the base metal?

1/4 inch.

What are the two types of indicating mediums available for magnetic particle inspection?

Wet and dry process materials.

What defects can circular magnetization of a part detect?

Defects perpendicular to the long axis of the part.

What tool is generally used to set a divider to an exact dimension?

Surface gauge.

How are the side clearances of piston rings measured?

With a thickness gauge.

What indicates that a part has cooled too quickly after welding?

Discoloration of the base metal.

What is Alclad?

A metal consisting of aluminum alloy surface layers and a pure aluminum core.

Which type of crack can be detected by magnetic particle inspection using either circular or longitudinal magnetization?

Cracks that are perpendicular to the magnetic field.

How can the dimensional inspection of a bearing in a rocker arm be accomplished?

Using longitudinal inspection.