ATP Written Test – Airplane Systems

The primary flight control surfaces allow the pilot to control an airplane's movement around its lateral, longitudinal, and vertical axes. The primary flight controls are the elevator, ailerons, and rudder.

The primary flight control surfaces allow the pilot to control an airplane's movement around its lateral, longitudinal, and vertical axes. The primary flight controls are elevators, ailerons, and rudders.

Leading-edge flaps, speed brakes, spoilers, trailing-edge flaps, and leading-edge slats are auxiliary (secondary) wing flight control surfaces.

Some large aircraft use two sets of ailerons (inboard and outboard). At high airspeeds, the aerodynamic loads from use of the outboard ailerons twist the wingtips. The outboard ailerons are locked in the neutral position during high-speed flight.

Some large aircraft use two sets of ailerons (inboard and outboard). At high airspeeds, the aerodynamic loads from use of the outboard ailerons twist the wingtips. The outboard ailerons are locked in the neutral position during high-speed flight.

Some large aircraft use two sets of ailerons (inboard and outboard). At high airspeeds, the aerodynamic loads from use of the outboard ailerons twist the wingtips. The outboard ailerons are locked in the neutral position during high-speed flight.

When hydraulic pressure is lost to the primary controls, the control tabs unlock from their actuating cylinders and allow control wheel inputs. This method of secondary control is known as manual reversion.

The elevator trim tab acts on the elevators, which in turn act upon the entire airplane. This allows the pilot to adjust the angle of attack of the elevators, thus modifying the downward tail load for any airspeed in flight and eliminating the need to exert continuous flight-control pressures.

Once adjusted, an elevator adjustable trim tab remains fixed for all positions relative to the primary control surface as the primary control surface is moved.

The servo tab aids the pilot in moving a primary control surface and in holding it in the desired position.

Movement of the servo tab in one direction causes the primary control surface to move in the opposite direction. If a servo tab on an aileron is deflected upward, the aileron is deflected downward, increasing the angle of attack on that wing, resulting in greater lift on that wing.

Since the anti-servo tab moves in the same direction as the control surface, it produces a stabilizing force that increases control force pressures.

An anti-servo tab, as found on the trailing edge of a stabilator, moves in the same direction as the primary flight control surface.

High-lift devices increase lift at low airspeeds, allowing lowered landing and takeoff speeds.

The leading-edge flap is similar in operation to the plain flap. When actuated, the leading edge of the wing extends in a downward direction to increase the camber of the wing, providing greater lift at low flight speeds.

The primary function of the leading edge flaps in the landing configuration during the flare before touchdown is to prevent flow separation at low airspeeds, therefore allowing lower landing and takeoff speeds.

The leading edge slot in a wing conducts the flow of high energy air into the boundary layer on the upper surface and delays airflow separation to some higher angle of attack. Thus, the slot simply delays stall to a higher angle of attack.

Leading-edge slats direct air from the high-pressure area under the wing to the upper surface, resulting in improved stall characteristics at lower speeds. They also increase lift at relatively slow airspeeds.

Leading-edge slats direct air from the high-pressure area under the wing to the upper surface, resulting in improved stall characteristics at lower speeds. They also increase lift at relatively slow airspeeds.

Spoilers are mounted on the upper surface of each wing, and they reduce lift without increasing airspeed. Their purpose is to spoil or disrupt the smooth flow of air over the wing to reduce the lifting force of the wing, thus increasing the rate of descent without increasing airspeed.

The purpose of spoilers is to spoil or disrupt the smooth flow of air over the wing to reduce the lifting force of the wing. Thus, flight spoilers may be used to reduce the wings' lift upon landing.

Spoilers are designed to spoil or disrupt the smooth flow of air over the wing to reduce the lifting force of the wing. Thus, ground spoilers are used to reduce the wings' lift upon landing.

Variations in the geometric pitch of the blades permit the propeller to operate with a relatively constant angle of attack along its length when in cruising flight. Propeller blades have variations to change the blade in proportion to the differences in speed of rotation along the length of the propeller and thereby keep thrust more nearly equalized along this length.

Water vapor, i.e., high relative humidity, will cause a significant reduction of power output of reciprocating engines but a negligible loss of thrust for a turbojet engine.

Because the density of air decreases as altitude increases, the supercharger compresses the thin air to maintain the preset power (manifold pressure) as the airplane climbs. When the critical altitude is reached, the turbine is rotating at its highest speed and can no longer compensate for decreasing manifold pressure after that altitude is exceeded.

The waste gate allows exhaust gas to be directed to drive the turbine of the turbocharger. The waste gate is normally controlled automatically to maintain the required amount of exhaust gas flow so the turbocharger can maintain the desired manifold pressure. At the critical altitude, the exhaust gas waste gate is fully closed, and the turbine is operating at maximum speed.

The pilot of a twin-engine airplane should become familiar with imminent stalls entered with various flap settings, power settings, and landing gear positions. Because of possible loss of control, stalls with one engine inoperative or at idle power and the other developing effective power are not to be practiced.

The airspeed indicator of a light, twin-engine airplane is marked (in addition to other normally marked airspeeds) with a red radial line at the minimum controllable airspeed with the critical engine inoperative, and a blue radial line at the best rate-of-climb airspeed with one engine inoperative.

VMC represents the minimum controllable airspeed with a critical engine inoperative. FAA regulations require that, in an airplane at VMC, the pilot must at least be able to stop the turn which results when the critical engine is suddenly made inoperative within 20° of the original heading using max rudder deflection and a max bank of 5° into the operative engine. Also, after recovery, the pilot must maintain the airplane in straight flight with not more than 5° bank wing lowered toward the operating engine. This does not mean that the airplane must be able to climb or even to hold altitude. It means only that a heading can be maintained.

For an airplane with unsupercharged engines, VMC decreases as altitude is increased; i.e., directional control can be maintained at a lower airspeed than at sea level. VMC is a function of power, which decreases with altitude. It is possible for the airplane to reach a stall speed prior to the loss of directional control.

VMC is greater when the center of gravity is at the most rearward allowable position. Since the airplane rotates around its center of gravity, the moments are measured using that point as a reference. A rearward CG would not affect the thrust moment but would shorten the arm to the center of the rudder's horizontal lift, which would mean that a higher force or airspeed would be required to provide the necessary rudder effectiveness.

When one engine fails on a light twin, the climb performance loss is greater than 50% because climb performance is a function of thrust horsepower in excess of that required for level flight. When power is increased in both engines in level flight and airspeed is held constant, the airplane will climb at a rate depending on the power added. When one engine fails, however, not only does it lose power, but the drag increases
considerably because of asymmetric thrust. The operating engine must carry the full burden alone, and climb performance may be reduced by 80% or more.

On twin-engine airplanes if the propellers rotate in the same direction (most U.S.-designed engines rotate clockwise when viewed from the rear) and both engines develop an equal amount of thrust, the asymmetric propeller thrust, or "P-factor," results in a center of thrust at the right side of each engine. The turning (or yawing) force of the right engine is greater than the left engine because the center of thrust is much farther away from the centerline of the fuselage; it has a longer arm. Thus, when the right engine is operative and the left engine is inoperative, the turning (or yawing) force is greater than with a good left engine and an inoperative right engine.
Directional control may be difficult when the left (or critical) engine is suddenly inoperative.

Flight tests have shown that holding the ball of the turn coordinator in the center while maintaining heading with wings level increases VMC as much as 20 kt. due to increased drag. Banking into the operative engine sufficiently to achieve zero sideslip (usually 5° or less) reduces VMC and ensures that the airplane will be in a minimum drag configuration for best climb performance. Engine-out flight with the ball centered is
never correct.

Slush on the runway may dictate adjustments, such as a reduction in critical engine failure speed (V1), an increase in required runway length, or a penalty in runway limited weight. An inoperative antiskid system may have the same requirements according to the airplane flight manual or company operations manual.

On normal takeoffs, liftoff should never take place until the airspeed reaches and exceeds VMC. The FAA recommends VMC + 5 kt. before liftoff. The safest and most efficient climb procedure is one in which the airplane leaves the ground slightly above VMC, accelerates to VY (best rate of climb), and climbs at VY for both engines, not single-engine.

When an engine failure occurs at an altitude above the single-engine ceiling, altitude will be lost. In an airplane not capable of maintaining altitude with an engine inoperative under existing circumstances, the airspeed should be maintained at VYSE so as to conserve altitude as long as possible.

In most light twins, a single-engine approach can be accomplished with the flight path and procedures almost identical to a normal approach and landing. However, neither full flaps nor the landing gear should be extended until the landing is assured.

There is a relatively slow rise in temperature as the air passes through the compressor inlet to the compressor discharge. The air is discharged into the combustion chamber. At the front of the combustion chamber are the fuel spray nozzles. The temperature increases rapidly in the combustion chamber and is cooled by a secondary airflow. The turbine inlet is subjected to the highest temperature in the turbojet engine. High-temperature, high-energy combustion gas is delivered through the turbine inlet from the combustion chamber. The temperature decreases through the turbine and exhaust nozzle.

A high ambient air temperature at a given pressure altitude relates to a high density altitude or a decrease in air density. Thrust is reduced because of low air density and low mass flow. Also, thrust and fuel flow are reduced further because of high compressor inlet temperature.

A high ambient temperature at a given pressure altitude relates to a high density altitude or a decrease in air density. Thrust is reduced because of the low air density and low mass flow. Also, thrust and fuel flow are reduced further because of high compressor inlet temperature.

Altitude is one factor which strongly affects the performance of the turbojet engine. An increase in altitude produces a decrease in density and pressure. This high density altitude causes a decrease in the engine air mass flow and, thus, a decrease in thrust output.

The operating characteristics of the turbojet or turboprop engine provide various operating limitations. Limiting exhaust gas temperature is the most important restriction to the operation of the turbojet or turboprop engine.

In addition to providing jet thrust, the turboprop engine requires additional turbine stages to continue the expansion of gases in the turbine section and to extract a very large percent of the exhaust gas energy as shaft power. The turboprop is primarily a power-producing machine, and the jet thrust is a small amount of the output propulsive power. The turboprop engine is rated by equivalent shaft horsepower (ESHP), which is a measure of shaft horsepower and jet thrust.

The ESHP will vary with altitude in a manner similar to the thrust output of the turbojet because the higher altitude produces much lower density and engine mass flow.

The minimum specific fuel consumption is obtained at relatively high power setting and high altitudes. The low inlet air temperature reduces the specific fuel consumption, and the lowest is obtained near altitudes of 25,000 to 35,000 ft. (or to the tropopause).

Reverse thrust of turbojet engines will usually employ some form of vanes, buckets, or clamshells in the exhaust to turn or direct the exhaust gases forward. Reverse thrust must be applied immediately after ground contact for maximum effectiveness in reducing landing distance.

Reverse thrust of propellers is obtained by rotating the blade angle well below the low pitch stop and applying engine power. The action is to extract a large amount of momentum from the airstream and create negative thrust. Maximum effectiveness is achieved by use of maximum reverse power immediately after the airplane is in contact with the runway.

If the ram air input and the drain hole are blocked, the pressure is trapped in the system, and the airspeed indicator will react as an altimeter. During a descent, the airspeed indication will decrease.

If the ram air and the drain hole are blocked, the pressure is trapped in the system, and the airspeed indicator will react as an altimeter: higher indicated airspeed at higher altitudes and lower indicated airspeed at lower altitudes.

If both the pitot tube input and the drain hole on the pitot system are blocked, the airspeed indication will be constant at any given altitude.

If the ram air input to the pitot head is blocked by ice but the drain hole and static port remain open, the pressure in the line to the airspeed indicator will vent out through the drain hole. Thus, the airspeed indication will drop to zero.