Aircraft Systems

Pilots are encouraged to turn on their landing lights when operating below 10,000 feet, day or night, especially when operating within 10 miles of any airport or in conditions of reduced visibility and in areas where flocks of birds may be expected.

If the temperature is between -7°C (20°F) and 21°C (70°F) with visible moisture or high humidity, the pilot should be constantly on the alert for carburetor ice. Answer (B) is incorrect because icing is less likely to occur above 70°F. Answer (C) is incorrect because icing is less likely to occur below 20°F.

If the proper grade of fuel is not available, it is possible (but not desirable) to use the next higher (aviation) grade as a substitute. Answer (B) is incorrect because burning lower octane fuel causes excessive engine temperatures. Answer (C) is incorrect because only aviation fuel should be used, except under special circumstances.

The preflight inspection should be a thorough and systematic means by which the pilot determines that the airplane is ready for safe flight. Most AFM or POH contain a section devoted to a systematic method of performing a preflight inspection that should be used by the pilot for guidance.

If the temperature is between -7°C (20°F) and 21°C (70°F), with visible moisture or high humidity, the pilot should constantly be on the alert for carburetor ice.

An aircraft must display lighted position lights from sunset to sunrise. Answer (A) is incorrect because it applies to logging of night time. Answer (B) is incorrect because it applies to the night landing requirement.

The dual ignition system has two magnetos to supply the electrical current to two spark plugs for each combustion chamber. This provides both a redundancy of ignition and an improvement of engine performance. Answer (B) is incorrect because heat distribution is not affected by the ignition system. Answer (C) is incorrect because cylinder head pressure in not affected by the ignition system.

On aircraft equipped with a constant-speed propeller, the throttle controls the engine power output which is registered on the manifold pressure gauge. The propeller control changes the pitch angle of the propeller and governs the RPM which is indicated on the tachometer. On most airplanes, for any given RPM, there is a manifold pressure that should not be exceeded. If an excessive amount of manifold pressure is carried for a given RPM, the maximum allowable pressure within the engine cylinders could be exceeded, thus putting undue strain on them. Answer (A) is incorrect because high manifold pressure is allowable with high RPM settings, within specification limits. Answer (C) is incorrect because the mixture should be leaned for best performance.

If the temperature is between -7°C (20°F) and 21°C (70°F) with visible moisture or high humidity, the pilot should be constantly on the alert for carburetor ice. Answer (A) is incorrect because carburetor icing is more likely with high humidity. Answer (B) is incorrect because carburetor icing is more likely with high humidity.

As soon as the engine starts, check for unintentional movement of the aircraft and set power to the recommended warm-up RPM. The oil pressure should then be checked to determine that the oil system is functioning properly with pressure at recommended levels within the manufacturer's time limit. Answer (B) is incorrect because this is usually done at the end of the flight. Answer (C) is incorrect because brakes are checked when beginning to taxi.

The downward-moving blade on the right side of the propeller has a higher angle of attack and greater action and reaction than the upward moving blade on the left. This results in a tendency for the airplane to yaw around the vertical axis to the left. Answer (A) is incorrect because it describes the characteristics involved with torque effect. Answer (C) is incorrect because it describes gyroscopic precession.

A constant-speed propeller permits the pilot to select the blade angle that will result in the most efficient performance for a particular flight condition. A low blade angle allows higher RPM and horsepower, desirable for takeoffs. An intermediate position can be used for subsequent climb. After airspeed is attained during cruising flight, the propeller blade may be changed to a higher angle for lower RPM, reduced engine noise, generally lower vibration, and greater fuel efficiency. Answer (A) is incorrect because a constant-speed propeller is not used to maintain airspeed, but rather constant engine RPM. Answer (C) is incorrect because a constant-speed propeller may not be smoother or operate with less vibration than a fixed-pitch propeller.

The effects of P-factor, or asymmetric propeller loading, usually occur when the airplane is flown at high angles of attack (or a high deck angle for a PPC) and at high power settings. Answer (A) is incorrect because the thrust differential between ascending and descending propeller blades at low angles of attack is slight. Answer (C) is incorrect because at higher airspeeds, an aircraft's angle of attack decreases in straight-and-level flight; therefore propeller-blade differential thrust becomes negligible.

The pilot-in-command of an aircraft is responsible for determining whether that aircraft is in condition for safe flight.

Use of carburetor heat tends to reduce the output of the engine and also to increase the operating temperature.

In a carburetor system, outside air flows into the carburetor and through a venturi (a narrow throat in the carburetor). When air flows rapidly through the venturi, a low pressure area is created. This low pressure allows the fuel to flow through the main fuel jet (located within the throat) and into the airstream where it mixes with the flowing air. Answer (A) is incorrect because fuel, rather than air, is metered manually with the mixture control. Answer (C) is incorrect because there is a decrease in air pressure.

Pilots are encouraged to turn on their landing lights when operating below 10,000 feet, day or night, especially when operating within 10 miles of any airport or in conditions of reduced visibility and in areas where flocks of birds may be expected.

When carburetor heat is applied, the air-fuel mixture of an engine will be enriched because any given volume of hot air is less dense than cold air of the same volume. This condition would be aggravated at high altitude where, because of decreased air density, the mixture is already richer than at sea level. Answer (B) is incorrect because the pilot should taxi back only if positive results were not obtained by leaning the mixture. Answer (C) is incorrect because detonation would not occur if the mixture was too rich, and a rich fuel mixture was the condition described in the question.

Fuel injection systems are less susceptible to icing than carburetor systems because of the lack of the temperature drop caused by the venturi in a carburetor. Be aware that one can acquire carburetor ice even without easily visible moisture and, in the right circumstances, even at full power. Answer (B) is incorrect because the venturi throat of carburetors makes them more susceptible to icing than fuel injection systems. Answer (C) is incorrect because the venturi throat of carburetors makes them more susceptible to icing than fuel injection systems.

To avoid excessive cylinder head temperatures, a pilot can open the cowl flaps, increase airspeed, enrich the mixture, or reduce power. Any of these procedures will aid in reducing the engine temperature. Answer (B) is incorrect because increasing the RPM increases the engine's internal heat. Answer (C) is incorrect because reducing the airspeed decreases the airflow needed for cooling, thus increasing the engine's temperature.

To avoid excessive cylinder head temperatures, a pilot can open the cowl flaps, increase airspeed, enrich the mixture, or reduce power. Any of these procedures will aid in reducing the engine temperature. Establishing a shallower climb (increasing airspeed) increases the airflow through the cooling system, reducing high engine temperatures. Answer (B) is incorrect because reducing airspeed hinders cooling, and increasing RPM will further increase engine temperature. Answer (C) is incorrect because increasing RPM will increase engine temperature.

Because of the hazards involved in hand-starting airplane engines, it is extremely important that a competent pilot be at the controls in the flight deck and that all communications and procedures be agreed upon and rehearsed beforehand. Answer (A) is incorrect because the person propping the engine is not required to be a pilot, and calling 'contact' is not required. Answer (C) is incorrect because a pilot must be in control of the aircraft, not only in the flight deck. Also, the person propping the engine calls out the commands.

Water in the fuel system is dangerous and the pilot must prevent contamination. The fuel tanks should be filled after each flight, or at least after the last flight of the day. This will prevent moisture condensation within the tank, since no air space will be left inside. Answer (A) is incorrect because water will settle to the bottom of a gas tank. Answer (B) is incorrect because fuel is allowed to expand by the fuel vent, whether the tanks are full or not.

Maintaining the proper glide speed (safe airspeed) is the most important rule to remember in the event of a power failure. Answer (B) is incorrect because these steps should be taken only after establishing the proper glide speed. Answer (C) is incorrect because these steps should be taken only after establishing the proper glide speed.

Airplanes have a red light on the left wing tip, a green light on the right wing tip and a white light on the tail. The flashing red light is the rotating beacon which can be seen from all directions around the aircraft. When the only steady light seen is white, then the airplane is headed away from the observing pilot.

When both a red and green light of another airplane are observed, the airplane would be flying in a general direction toward you. Airplanes have a red light on the left wing tip, a green light on the right wing tip and a white light on the tail.

14 CFR Part 91 places primary responsibility on the owner or operator for maintaining an aircraft in an airworthy condition.

Preignition is defined as ignition of the fuel prior to normal ignition. Answer (A) is incorrect because combustion is the normal engine process. Answer (C) is incorrect because detonation is the exploding of the air-fuel mixture.

Oil, used primarily to lubricate the moving parts of the engine, also cools the internal parts of the engine as it circulates. Answer (A) is incorrect because most air-cooled aircraft engines do not have thermostats. Answer (B) is incorrect because, although air-cooling is important, internal cooling is more reliant on oil circulation. Air cools the cylinders, not the exhaust manifold.

Most training aircraft use reciprocating engines because they are relatively simple and inexpensive to operate.

To prevent detonation, the pilot should use the correct grade of fuel, maintain a sufficiently rich mixture, open the throttle smoothly, and keep the temperature of the engine within recommended operating limits. Some aircraft have an automatically enriched mixture for enhanced cooling in takeoff and climb-out at full throttle. Lowering the nose will allow the aircraft to gain airspeed, which eventually lowers the engine temperature. Answer (A) is incorrect because leaning the mixture increases engine temperatures; detonation results from excessively high engine temperatures. Answer (C) is incorrect because although a richer fuel mixture results from applying carburetor heat, the heat may offset the cooling effect of the mixture change. The most efficient initial action would be to increase airspeed.

Carburetors are normally calibrated at sea level pressure to meter the correct air-fuel mixture. As altitude increases, air density decreases and the amount of fuel is too great for the amount of air--the mixture is too rich. This same result may be brought about by the application of carburetor heat. The heated air entering the carburetor has less density than unheated air and the air-fuel mixture is enriched. Answer (A) is incorrect because the air-fuel mixture becomes richer. Answer (C) is incorrect because the air-fuel mixture becomes richer.

If you experience an in-flight electrical system failure, you would have an avionics equipment failure, and you could not use your electrical fuel boost pump. Answer (B) is incorrect because the ignition system of an aircraft reciprocating engine is powered by two self-contained magnetos that are not dependent upon the aircraft electrical system. Answer (C) is incorrect because the engine-driven fuel pumps are mechanical and not dependent on the electrical system.

For airplanes with a fixed-pitch propeller, the first indication of carburetor ice is loss of RPM. Answer (A) is incorrect because the RPM will decrease, not increase. Answer (B) is incorrect because this symptom may develop, but only after a loss of RPM.

High engine temperatures can lead to loss of power, excessive oil consumption, detonation, and serious engine damage.

Two fuel pump systems are used on most airplanes. The main pump system is engine driven and an auxiliary electric driven pump is provided for use in the event the engine pump fails. The auxiliary pump, commonly known as the boost pump, provides added reliability to the fuel system, and is also used as an aid in engine starting. The electric auxiliary pump is controlled by a switch in the flight deck.

Air density increases in the descent, but the amount of fuel drawn into the carburetor remains the same. To re-establish a balanced air-fuel mixture in a descent, the mixture control must be adjusted toward rich.Answer (B) is incorrect because the mixture will become too lean and the engine temperature will increase. Answer (C) is incorrect because an excessively lean mixture will result.

When heat is applied there will be a drop in RPM in airplanes equipped with fixed-pitch propellers. If carburetor ice is present, there will normally be a rise in RPM after the initial drop. Then, when the carburetor heat is turned off, the RPM will rise to a setting greater than that before application of the heat. The engine should also run more smoothly after the ice has been removed. Answer (A) is incorrect because the warm air decreases engine RPM; melting ice also decreases RPM. Once the ice is gone, the RPM increases. Answer (B) is incorrect because this would happen if there was no carburetor ice to begin with.

The mixture becomes richer as the airplane gains altitude, because the carburetor meters the same amount of fuel as at sea level. Leaning the mixture control prevents this by decreasing the rate of fuel discharge to compensate for the decrease in air density. Answer (A) is incorrect because the pilot would increase the amount of fuel to compensate for increased air density. Answer (C) is incorrect because the pilot would decrease the amount of fuel to compensate for decreased air density.

On aircraft equipped with a constant-speed propeller, the throttle controls the engine power output which is registered on the manifold pressure gauge. The propeller control changes the pitch angle of the propeller and governs the RPM which is indicated on the tachometer. Answer (B) is incorrect because the propeller control does not maintain a constant pitch, it changes pitch in order to hold a constant RPM. Answer (C) is incorrect because the throttle does not directly control RPM, and mixture control does not regulate power.

Operating an engine at a higher temperature than it was designed for will cause loss of power, excessive oil consumption, and detonation. It will also lead to serious permanent injury to the engine including scoring of cylinder walls, damage to pistons and rings, and burning and warping of valves. Answer (A) is incorrect because internal engine damage is more likely to result before external damage occurs. Answer (C) is incorrect because excessively high engine temperatures seriously affect an aircraft engine.

If the ground wire between a magneto and the ignition switch becomes disconnected, the primary current cannot be directed to ground, and the engine cannot be shut down by turning the switch to the OFF position.

Using fuel of a lower rating is harmful under any circumstances because it may cause loss of power, excessive heat, burned spark plugs, burned and sticky valves, high oil consumption, and detonation. Answer (A) is incorrect because the carburetor will meter the lower-grade fuel the same as the proper fuel. Answer (B) is incorrect because lower-grade fuel raises cylinder head temperatures.

Detonation or knock is a sudden explosion or shock to a small area of the piston top, rather than the normal smooth burn in the combustion chamber. Answer (B) is incorrect because detonation may occur with an excessively lean fuel mixture and a loss in power. Answer (C) is incorrect because this prescribes preignition.

Oil, used primarily to lubricate the moving parts of the engine, also helps reduce engine temperature by removing some of the heat from the cylinders. Therefore, if the oil level is too low, the transfer of heat to less oil would cause the oil temperature to rise. Answer (B) is incorrect because the higher the viscosity, the better the lubricating and cooling capability of the oil. Answer (C) is incorrect because a rich air-fuel mixture usually decreases engine temperature.

Carburetors are normally calibrated at sea level pressure to meter the correct air-fuel mixture. As altitude increases, air density decreases and the amount of fuel is too great for the amount of air--the mixture is too rich. This same result may be brought about by the application of carburetor heat. The heated air entering the carburetor has less density than unheated air and the air-fuel mixture is enriched. Answer (A) is incorrect because applying carburetor heat decreases the density of air but does not affect the air going through the carburetor. Answer (C) is incorrect because the mixture is enriched by applying carburetor heat.

Excessively high engine temperatures result from insufficient cooling caused by too lean a mixture, too low a grade of fuel, low oil, or insufficient airflow over the engine. Answer (B) is incorrect because higher octane fuel will burn at lower temperatures, keeping the engine cooler. Answer (C) is incorrect because high oil pressure does not cause high engine temperatures.

The effect of torque increases in direct proportion to the engine power, airspeed, and airplane attitude. If the power setting is high, the airspeed slow, and the angle of attack high (or a high deck angle for a PPC), the effect of torque is greater. Answer (B) is incorrect because the least amount of torque effect is produced under these conditions. Answer (C) is incorrect because torque effect is negligible at higher airspeeds due to increased stability generated by more airflow moving over all airfoils.

Airplanes have a red light on the left wing tip, a green light on the right wing tip and a white light on the tail. The flashing red light is the rotating beacon which can be seen from all directions around the aircraft. If the only steady light seen is red, then the airplane is crossing from right to left in relation to the observing pilot.

Many aircraft are equipped with fuel strainers located at the lowest point in the fuel lines and sump drains installed at the lowest point in each fuel tank. In order to completely purge all of the liquid water from the fuel system, the fuel strainer drain and the sumps in all of the tanks must be drained.

Excessively high engine temperatures can result from insufficient cooling caused by too lean a mixture, too low a grade of fuel, low oil, or insufficient airflow over the engine. Answer (A) is incorrect because a richer fuel mixture will normally cool an engine. Answer (B) is incorrect because high oil pressure does not cause high engine temperatures.

Detonation is a sudden explosion, or instantaneous combustion, of the air-fuel mixture in the cylinders, producing extreme heat and severe structural stresses on the engine. Answer (A) is incorrect because detonation does not have anything to do with the wiring. Answer (B) is incorrect because this describes preignition, not detonation.