Based on our vast experience with EASA PART 66 examination questions and question databanks, we have prepared a practice example of questions with explanations to practice for your next exam.
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Module 8: Basic Aerodynamics
- As altitude increases in the atmosphere, how does pressure change?
Options:
A) decreases at constant rate
B) decreases exponentially
C) increases exponentiallyCorrect Answer: b) decreases exponentially
Explanation: Atmospheric pressure decreases exponentially with increasing altitude because air is compressible, and the density of air (and thus the weight of the air column above) reduces significantly with height.
- If the gauge pressure on a standard day at sea level is 25 PSI, what is the absolute pressure?
Options:
A) 39.7 PSI
B) 10.3 PSI
C) 43.8 PSICorrect Answer: a) 39.7 PSI
Explanation: Absolute pressure is the sum of gauge pressure and atmospheric pressure. At sea level on a standard day, atmospheric pressure is approximately 14.7 PSI. Therefore, Absolute Pressure = 25 PSI + 14.7 PSI = 39.7 PSI.
- How is the service ceiling of an aircraft affected as the air temperature becomes colder?
Options:
A) reduces
B) increases
C) remains the sameCorrect Answer: b) increases
Explanation: Colder air is denser. Denser air improves engine performance and lift, allowing an aircraft to achieve a higher service ceiling where the rate of climb drops below a specified value.
- What happens to Indicated Airspeed (IAS) at the point of stall as height increases?
Options:
A) It decreases
B) It is practically constant
C) It increasesCorrect Answer: b) It is practically constant
Explanation: IAS at stall remains practically constant with height because stall is determined by the angle of attack, which relates to the air density, and IAS compensates for density changes, presenting a consistent aerodynamic effect.
- With increasing altitude, what is the typical trend of atmospheric pressure?
Options:
A) decreases exponentially
B) decreases at constant rate
C) increases exponentiallyCorrect Answer: a) decreases exponentially
Explanation: Atmospheric pressure decreases exponentially with increasing altitude. This is a fundamental characteristic of the Earth’s atmosphere.
- In comparison to International Standard Atmosphere (ISA) conditions, what is the approximate temperature at 30,000 ft?
Options:
A) -60°C
B) 0°C
C) -45°CCorrect Answer: c) -45°C
Explanation: According to ISA the temperature lapse per 1000 feet is -1,98 deg. C. On altitude of 0 feet the ISO temperature is 15 deg. C. Considering the temperature lapse of 1.98 deg. C per 1000 feet the for 30.000 feet would be -59,4 deg. C, adding ISA 15 deg. C brings you to rough -45 deg. C.
- At what approximate altitude is the tropopause typically found?
Options:
A) 36,000 ft
B) 57,000 ft
C) 63,000 ftCorrect Answer: a) 36,000 ft
Explanation: The tropopause is the boundary layer between the troposphere and the stratosphere. In the ISA, it is defined as occurring at 36,089 feet (approximately 11 km or 36,000 ft).
- The millibar is a standard unit of:
Options:
A) atmospheric temperature
B) pressure altitude
C) barometric pressureCorrect Answer: c) barometric pressure
Explanation: The millibar (mb) is a unit of atmospheric pressure, commonly used in meteorology to report barometric pressure readings.
- A barometer is an instrument that indicates:
Options:
A) pressure
B) density
C) temperatureCorrect Answer: a) pressure
Explanation: A barometer is used to measure atmospheric pressure.
- Which condition refers to the actual quantity of water vapor present within a mixture of air and water?
Options:
A) Relative humidity
B) Absolute humidity
C) Dew pointCorrect Answer: b) Absolute humidity
Explanation: Absolute humidity is the total mass of water vapor present in a given volume of air, regardless of temperature.
- Which of the following air-water vapor mixtures will weigh the least?
Options:
A) 98 parts of dry air and 2 parts of water vapour
B) 50 parts of dry air and 50 parts of water vapour
C) 35 parts of dry air and 65 parts of water vapourCorrect Answer: c) 35 parts of dry air and 65 parts of water vapour
Explanation: Water vapor (H2O) has a lower molecular mass (approx. 18 g/mol) than the average molecular mass of dry air (approx. 29 g/mol). Therefore, the air-water vapor mixture with the highest proportion of water vapor will be the least dense and thus weigh the least.
- What is the ratio of the existing water vapor in the atmosphere to the maximum amount that would be present if the air were saturated at its current temperature and pressure?
Options:
A) Absolute humidity
B) Dew point
C) Relative humidityCorrect Answer: c) Relative humidity
Explanation: Relative humidity is the ratio, expressed as a percentage, of the amount of water vapor in the air to the maximum amount of water vapor the air can hold at that temperature and pressure.
- Which statement accurately describes heat and/or temperature?
Options:
A) Temperature is a measure of the kinetic energy of the molecules of any substance.
B) Temperature is a measure of the potential energy of the molecules of any substance.
C) There is an inverse relationship between temperature and heat.Correct Answer: a) Temperature is a measure of the kinetic energy of the molecules of any substance.
Explanation: Temperature is a measure of the average kinetic energy of the particles (atoms or molecules) within a substance. Heat is the transfer of thermal energy between objects due to a temperature difference.
- The temperature to which humid air must be cooled, at a constant pressure, to reach saturation is called the:
Options:
A) absolute humidity
B) dew point
C) relative humidityCorrect Answer: b) dew point
Explanation: The dew point is the temperature at which a given parcel of humid air becomes saturated with water vapor and condensation begins to form (e.g., dew, fog, or clouds).
- On a very hot day with ambient temperature higher than ISA, if the pressure altitude is 20,000 ft, how will the density altitude compare?
Options:
A) the same
B) greater than 20,000ft
C) less than 20,000ftCorrect Answer: b) greater than 20,000ft
Explanation: Density altitude increases with higher temperatures. If the ambient temperature is hotter than ISA for a given pressure altitude, the air is less dense, resulting in a density altitude that is greater than the pressure altitude.
- In the International Standard Atmosphere (ISA), how is the temperature lapse rate with altitude assumed to be?
Options:
A) dependent on pressure and density changes
B) linear
C) non linearCorrect Answer: b) linear
Explanation: In the standard ISA model, the temperature decreases at a constant (linear) rate of 1.98 deg Celsius per 1,000 feet up to the tropopause.
- Arrange the atmospheric layers in correct sequence from the ground upwards:
Options:
A) tropopause, stratosphere, troposphere
B) tropopause, troposphere, stratosphere
C) troposphere, tropopause, stratosphereCorrect Answer: c) troposphere, tropopause, stratosphere
Explanation: The layers of the Earth’s atmosphere, starting from the ground up, are: troposphere, stratosphere, mesosphere, thermosphere, and exosphere. The tropopause is the boundary between the troposphere and stratosphere.
- Which of the following relationships between pressure types is correct?
Options:
A) Absolute pressure + Atmospheric pressure = Gauge pressure
B) Absolute pressure = Gauge pressure + Atmospheric pressure
C) Atmospheric pressure = Absolute pressure + Gauge pressureCorrect Answer: b) Absolute pressure = Gauge pressure + Atmospheric pressure
Explanation: Absolute pressure is the total pressure measured relative to a perfect vacuum, and it is equal to the sum of the gauge pressure (pressure relative to ambient atmospheric pressure) and the local atmospheric pressure.
- As altitude increases, what happens to the ratio of Nitrogen to Oxygen in the atmosphere?
Options:
A) Increases
B) Decreases
C) Stays the sameCorrect Answer: c) Stays the same
Explanation: While overall air density decreases with altitude, the ratio of major gases like nitrogen and oxygen remains practically constant throughout the troposphere and lower stratosphere. They are well-mixed.
- What happens to the density of air as altitude is increased?
Options:
A) Decreases
B) Stays the same
C) IncreasesCorrect Answer: a) Decreases
Explanation: As altitude increases, the air molecules become more spread out due to reduced gravitational pull and fewer molecules above to compress them, leading to a decrease in air density.
- An aircraft is flying at a speed of 720 nautical miles per hour. To calculate its speed in MPH (miles per hour), what conversion factor do you use?
Options:
A) divide by 0.83
B) multipy by 0.83
C) multiply by 1.15Correct Answer: c) multiply by 1.15
Explanation: To convert nautical miles (knots) to statute miles (MPH), you multiply by approximately 1.15078. So, approx 1.15.
