FAA Aircraft Performance

4-(3291)- What effect does high density altitude have on aircraft performance? A- It increases engine performance. *B- It reduces climb performance. C- It increases takeoff performance.

*B- It reduces climb performance Expl- An increase in air temperature or humidity, or a decrease in air pressure (which results in a higher density altitude), will significantly decrease both power output and propeller efficiency.

5- (Refer to Figure 8.) What is the effect of a temperature increase from 25 to 50°F on the density altitude if the pressure altitude remains at 5,000 feet? A- 1,200-foot increase. B- 1,400-foot increase. *C- 1,650-foot increase.

*C- 1,650-foot increase. Expl- Referencing FAA Figure 8, use the following steps: 1. Enter the density altitude chart at 25°F. Proceed upward to intersect the 5,000-foot pressure altitude line. From the point of intersection, move left to the edge of the chart and read a density altitude of 3,850 feet. 2. Enter the density altitude chart at 50°F. Proceed upward to the 5,000-foot pressure altitude line. From the point of intersection, move left to the edge of the chart and read a density altitude of 5,500 feet. 3. Determine the change in density altitude: 5,500 - 3,850 = 1,650 feet (increase)

3- (3290)-Which combination of atmospheric conditions will reduce aircraft takeoff and climb performance? A- Low temperature, low relative humidity, and low density altitude. B- High temperature, low relative humidity, and low density altitude. *C- High temperature, high relative humidity, and high density altitude.

*C- High temperature, high relative humidity, and high density altitude. Expl- An increase in air temperature or humidity, or a decrease in air pressure (which results in a higher density altitude), will significantly decrease both power output and propeller efficiency.

2-(3289)- If the outside air temperature (OAT) at a given altitude is warmer than standard, the density altitude is A- equal to pressure altitude. B- lower than pressure altitude. *C- higher than pressure altitude.

*C- higher than pressure altitude. Expl- If the temperature is above standard, the density altitude will be higher than pressure altitude.

1- (3246)- What effect does high density altitude, as compared to low density altitude, have on propeller efficiency and why? A- Efficiency is increased due to less friction on the propeller blades. *B- Efficiency is reduced because the propeller exerts less force at high density altitudes than at low density altitudes. C- Efficiency is reduced due to the increased force of the propeller in the thinner air.

b- Expl- The propeller produces thrust in proportion to the mass of air being accelerated through the rotating blades. If the air is less dense, propeller efficiency is decreased.