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The correct choice is (c) STEEL

For EXPLANATION I would SAY: Controls can be made using either steel or aluminium alloys. Controls refer to the CONTROL parts of an aircraft like control sticks, torsion tubes, bell-cranks etc. Wood and copper are not used.

Right option is (d) ALUMINIUM alloy

Easiest EXPLANATION: Aluminum alloy can be USED as a covering for wings in an aircraft. There are other materials that can be used, like fabric and plywood. CARBON, titanium and manganese alloy are not used for this PURPOSE.

Right option is (b) Plexiglass

The best explanation: Plexiglass is the material used in making aircraft windows. It is PREFERRED instead of plane GLASS. It has attractive properties, LIKE its strength and TRANSPARENCY. Aircraft windows are made of SEVERAL layers.

The correct ANSWER is (b) False

To ELABORATE: Cost should not be the only and primary consideration in the selection of materials. The materials that have good properties like high strength /weight ratio must be SELECTED, and cost can be a factor of selection among them later in the process. The quality of material must not be compromised DUE to cost.

The CORRECT choice is (a) NICKEL steel

To explain: Nickel steels are used in making bolts of an aircraft. Bolts are used in structural connections. Bolts made of nickel steel have higher Strength COMPARED to chrome-molybdenum bolts, which are used if there is a requirement of welding as nickel steel is not easy to WELD.

The correct choice is (d) THICK rubber

For explanation I would say: The wheels of landing gear are made of thick rubber. This is to absorb any shocks. The other part of the landing gear contains titanium ALLOYS. The wheels are pumped with gases like NITROGEN to AVOID explosions.

The CORRECT answer is (a) True

For explanation I would say: MAGNESIUM and its alloys are suitable to use while making helicopters. This is because it is lighter in WEIGHT compared to aluminium. It is a good STRUCTURAL metal to use. But it is not resistant to corrosion.

The correct choice is (a) Magnesium alloy sheets

Best explanation: Aircraft seats are MADE using magnesium alloy sheets. Aluminium alloy sheets can also be used. Pure magnesium is not used, as alloyed METALS typically have PREFERABLE properties COMPARED to elements in their pure state.

Right answer is (c) Douglas fir

Easiest explanation: Wing-tip BOWS can be manufactured using chrome-molybdenum, ALUMINIUM alloy and mild steel. However, Douglas fir is not used. Douglas fir is a type of tree whose wood can be used in manufacturing wing BEAMS.

Correct choice is (c) wing tips and stabilizer tips

To explain I would say: There are several non-metallic PARTS used in the CONSTRUCTION of an aircraft. Wing tips and stabilizer tips CONTAIN non-metallic parts. The different non-metallic parts used are TRANSPARENT PLASTICS, reinforced plastics, carbon fiber materials, etc.

The correct choice is (b) 2024-T4

The explanation is: 2024-T4 is used in MANUFACTURING several components of an aircraft like the fuselage, OIL tank and WINGS. It is used in WING covering, wing ribs, wing leading EDGE, wing beams, etc. 2024-T4 is a type of aluminium alloy. It is a part of the 2000 series of aluminium alloy.

The correct choice is (a) TITANIUM ALLOYS

Explanation: Both titanium alloys and aluminium alloys can be used in MAKING aircraft wings. Titanium alloys have good strength, low WEIGHT and are resistant to CORROSION. Aluminium alloys have high strength and high ductility.

The correct option is (a) physical

Easiest explanation: The dimension of a material is a physical property. Dimension is the physical MEASUREMENT of an object. Length, breadth and HEIGHT DESCRIBE the dimensions of an object. It is not an ECONOMIC, technological or mechanical property.

The correct option is (b) Ease of cutting a MATERIAL

Explanation: MACHINABILITY is the ease of cutting material. It is the CHANGE in the form of material along with being ECONOMICALLY beneficial, at a low cost. The machinability of a material is a technological factor.

Correct option is (b) 0.889 to 1.2446 MM

Easiest explanation: Oil tanks are usually made with aluminium or its alloys, ALTHOUGH magnesium can also be USED. The thickness of the sheets used is somewhere between 0.889 to 12.446 mm. The thickness depends upon VARIOUS parameters like shape, size, etc.

Right option is (a) Color

Best explanation: Color is the least considered factor in the selection of materials. The technological, physical and economic factors LIKE melting point, weldability and availability are MUCH more important as they affect SAFETY and PERFORMANCE more. Also, materials can be colored according to REQUIREMENTS.

Correct choice is (d) Maintenance cost plus the INITIAL cost

Easiest explanation: While considering the cost of SHOP equipment required, both the maintenance cost plus the initial cost of the material must be considered. This is an important economic consideration in the selection of MATERIALS used in the CONSTRUCTION of an aircraft.

The correct option is (d) 125,000 or 150,000 PSI

The BEST I can explain: Bushings are MANUFACTURED by heating METALS LIKE chrome-molybdenum steel to a temperature of 125,000 or 150,000 psi. Bushings can be replaced by new parts once they are worn out.

Right OPTION is (c) Aluminium alloy

The best I can explain: The fuselage of an aircraft is typically made of aluminium ALLOYS. The fuselage is the mainframe of an aircraft. Aluminium alloy is CHOSEN because it has favorable properties, like high ductility, high strength/weight ratio ETC.

Correct answer is (c) Availability

The best explanation: The availability of MATERIAL is an ECONOMIC consideration. The material being used for the construction of an aircraft must be AVAILABLE for all requirements. Structure and appearance are physical properties of a material.

Correct answer is (c) Yes, it is advantageous

Explanation: STANDARDIZATION of materials is an ADVANTAGE. It refers to using the available material in manufacturing different components, instead of STOCKING several materials that RESULT in RESIDUAL materials being left.

Right choice is (d) ELASTICITY

The explanation is: Elasticity is a mechanical property. It is the ABILITY of a material to return to its original SHAPE after the material undergoes DEFORMATION. Appearance and colour are physical properties of a material.

Right ANSWER is (a) Painting a protective LAYER

The explanation is: Materials that are not resistant to corrosion can be painted with a protective layer of another METAL. A few EXAMPLES of metals are CHROMIUM, nickel or zinc. Increasing the quantity of material or heating will not help.

Correct option is (a) True

For EXPLANATION: Porosity is the QUANTITY of VOID space present in the structure of a material. It is the ratio of PORE volume to the total structure volume. It is one of the physical PROPERTIES of a material.

Correct answer is (a) True

The EXPLANATION: Landing gear wheels are made of thick rubber. This is to absorb the shock WAVES and vibration caused when landing an AIRCRAFT. It also prevents the LOSS of fluids. Rubber is a good NONMETALLIC component of aircraft.

Right OPTION is (c) High fuel CONSUMPTION

Explanation: High fuel consumption is not an advantage. Moreover, ALUMINIUM has a low fuel consumption. It is light in weight compared to other metals like steel. It is ALSO a high strength alloy. It is resistant to corrosion.

Right ANSWER is (a) Castability

The EXPLANATION is: Castability is a technological factor of MATERIALS. The ease with which the material can be cast is called castability. The higher the castability, easier the PROCESS. MELTING point and availability are physical properties of a material.

Right option is (c) Resistance to cyclical stress

Easy EXPLANATION: The highest point up to which the material can RESIST cycles of stress. Aircraft are AFFECTED by several STRESSES and loads. It is important to consider their resistance to these loads and stresses to avoid failure.

Correct answer is (C) shock LOADS

For explanation I would SAY: An aircraft should be resistant to shock loads. Joining property and working property are important for the design and FABRICATION of components. Strength is an advantageous property for a material.

The correct ANSWER is (d) higher strength/WEIGHT ratio

Best explanation: The strength/weight ratio is an indication of the material’s ability to sustain the LOAD. Materials with HIGH weight are not preferred. Material with high strength and low weight have good strength/weight ratio, hence they are used.

Right answer is (b) A MATERIAL that requires supplementary operations to be USED in manufacturing

Easiest explanation: A material that requires supplementary operations before being used in manufacturing is called supplementary operational requirement. The operations vary depending on the material. A few examples are plating, heat treatment ETC. The materials cannot be used in their NATURAL state. This is a disadvantage as it is more costly and time-consuming.

The correct answer is (b) To PROTECT from excessive heating

The EXPLANATION: Thermal conductivity of a material is the rate at which it conducts heat. Low thermal conductivity is IMPORTANT because it prevents the systems from excessive heating hence preventing FAILURE. It does not affect the OXYGEN levels or increase the strength.