Chapter 1: Airplane Instruments 27

11. Answer (B) is correct (4894). (IFH Chap IV) 4894. What should be the indication on the magnetic In turns from a northerly heading in the Northern compass as you roll into a standard rate turn to the left Hemisphere, the compass will initially indicate a turn to from a north heading in the Northern Hemisphere? the opposite direction, and the compass heading will lag behind actual until the airplane approaches an east or A— The compass will indicate a turn to the left, but at a west heading. faster rate than is actually occurring. Answer (A) is incorrect because it describes a turn to B— The compass will initially indicate a turn to the right. the left from a southerly heading. Answer (C) is incorrect C— The compass will remain on north for a short time, because it describes a shallower-than-standard turn from then gradually catch up to the magnetic heading of north. the aircraft.

1.2 Pitot-Static System

12. Answer (A) is correct (4909). (IFH Chap IV) 4909. During flight, if the pitot tube becomes clogged The pitot-static system is a source of pressure for the with ice, which of the following instruments would be altimeter, vertical speed indicator, and airspeed indicator. affected? The pitot tube is connected directly to the airspeed indicator, and the static vents are connected directly to all A— The airspeed indicator only. three. The pressure of air coming into the pitot tube B— The airspeed indicator and the altimeter. (impact air pressure) is compared with the air pressure at C— The airspeed indicator, altimeter, and Vertical Speed the static system vents to determine airspeed. Indicator. Answer (B) is incorrect because the pitot tube is connected only to the airspeed indicator, not the altimeter. Answer (C) is incorrect because the pitot tube is connected only to the airspeed indicator, not the altimeter or vertical speed indicator.

13. Answer (C) is correct (4830). (AC 91-43) 4830. If both the ram air input and the drain hole of the When the airspeed indicator pitot tube and drain hole pitot system are blocked, what reaction should you are blocked, the airspeed indicator will react as an observe on the airspeed indicator when power is applied altimeter. There will be a constant pressure within the and a climb is initiated out of severe icing conditions? pitot tube, and as the pressure from the static source decreases during a climb, the indicated airspeed on the A— The indicated airspeed would show a continuous altimeter will increase. deceleration while climbing. Answer (A) is incorrect because, as there is an B— The airspeed would drop to, and remain at, zero. increase in altitude, the airspeed indicator will show an C— No change until an actual climb rate is established, increase in airspeed as the air pressure within the pitot then indicated airspeed will increase. tube is relatively greater than that of the static air. Answer (B) is incorrect because this reaction would occur if the ram air input, but not the drain hole, were blocked.

14. Answer (A) is correct (4854). (IFH Chap IV) 4854. What indication should a pilot observe if an When the airspeed indicator pitot tube and drain hole airspeed indicator ram air input and drain hole are are blocked, the airspeed indicator will react as an blocked? altimeter. There will be a constant pressure within the pitot tube, and as the pressure from the static source A— The airspeed indicator will react as an altimeter. decreases during a climb, the indicated airspeed on the B— The airspeed indicator will show a decrease with an altimeter will increase. increase in altitude. Answer (B) is incorrect because indicated airspeed C— No airspeed indicator change will occur during will increase, not decrease, with increases in altitude. climbs or descents. Answer (C) is incorrect because differential pressure between the pitot tube and static air source changes, and so does indicated airspeed.