FAA Aircraft Dispatcher (FAD)

Correct: Mmo is established to protect the aircraft from the adverse effects of transonic flow. At high altitudes, the speed of sound is lower, and reaching the critical Mach number leads to shock wave formation. These shock waves can cause a significant shift in the center of pressure, leading to Mach tuck, or cause airflow separation that results in high-speed buffet and reduced control effectiveness, as outlined in Federal Aviation Administration (FAA) certification standards for transport category aircraft.

Correct: In accordance with aerodynamic principles recognized by the Federal Aviation Administration, an increase in the angle of attack on a cambered airfoil causes the center of pressure to move forward. This occurs because the pressure distribution shifts toward the leading edge as the lift coefficient increases.

Incorrect: The strategy of suggesting the center of pressure moves aft incorrectly describes the behavior of cambered airfoils in subsonic flight. Simply assuming the center of pressure remains at a fixed chord position confuses this variable point with the aerodynamic center. Focusing only on a vertical shift fails to account for the necessary longitudinal redistribution of pressure across the chord.

Takeaway: On a cambered airfoil, the center of pressure moves forward as the angle of attack increases within the normal operating range.

Correct: In fully powered hydraulic systems, the actuators provide all the force required to move the control surfaces, which isolates the pilot from the natural aerodynamic feel. Without an artificial feel unit, a pilot could easily apply excessive control inputs at high speeds, leading to structural failure. The unit uses dynamic pressure inputs to increase control resistance as airspeed increases, maintaining a safe and intuitive handling quality.

Correct: Under US aviation regulations for transport category aircraft, a Class C cargo compartment must have a built-in fire extinguishing or suppression system. This system is required to maintain a sufficient concentration of the extinguishing agent for at least 60 minutes. This duration is intended to provide the flight crew with enough time to divert and land the aircraft safely at a suitable airport.

Correct: Cornering speed, often referred to as maneuvering speed (VA), is the intersection of the stall curve and the limit load factor. At this speed, the aircraft can generate exactly enough lift to reach its structural limit. If the pilot attempts to pull more G-loads at this speed, the aircraft will stall, thereby protecting the structure from exceeding its design limits. This provides a natural aerodynamic buffer against structural failure during abrupt control movements.

Correct: The FMS calculates the maximum altitude based on the aircraft’s ability to maintain a 0.3g buffer (1.3g total) before encountering aerodynamic buffet, ensuring safety during turns or in turbulence.

Incorrect: Relying solely on the intersection of thrust and drag at the best glide speed ignores the critical maneuver margins required for safe high-altitude flight. The strategy of equating stall speed to the maximum Mach number describes the aerodynamic ceiling but lacks the safety buffers used in FMS logic. Opting for a specific low rate of climb like one hundred feet per minute does not account for the buffet protection requirements mandated by the Federal Aviation Administration.

Takeaway: FMS maximum altitude calculations prioritize maneuver margins to ensure protection against high-altitude buffet onset.

Correct: The PRSOV is a dual-function component that maintains a steady pressure for downstream consumers like the environmental control system while allowing the crew or fire detection system to isolate the bleed source.

Correct: Mass-flow systems are preferred because the energy available in aviation fuel is directly proportional to its mass. Since fuel density changes significantly with temperature, a volumetric system would provide inconsistent data regarding the actual energy available to the engines. By measuring mass, the system ensures that the flight crew has an accurate understanding of the remaining range and endurance regardless of environmental conditions.

Correct: A check valve is the standard component used to maintain system integrity by preventing backflow, which is critical for protecting pumps and maintaining pressure in accumulators.

Incorrect: The strategy of venting fluid to prevent structural damage describes a relief valve, which responds to pressure magnitude rather than direction. Focusing on the manual or automatic direction of fluid to specific subsystems describes a selector valve. Opting for a priority valve describes a component that manages fluid distribution based on system importance rather than preventing backflow.

Takeaway: Check valves are essential for maintaining hydraulic system integrity by preventing the reverse flow of fluid.

Correct: Under US aviation standards, the ‘Normal’ setting on a diluter-demand regulator uses an aneroid-controlled valve to mix ambient cabin air with oxygen, providing a higher concentration as the cabin altitude increases. The ‘100%’ setting closes the air inlet, ensuring the pilot receives pure oxygen, which is necessary for protection against smoke, toxic fumes, or severe hypoxia.

Correct: If the manifold is isolated from its sources and the warning persists, the heat source must be upstream of the isolation point or the detection system itself is faulty. This is because the shutoff valves are designed to stop the flow of hot bleed air to the manifold, and a continued alert suggests the sensor is still triggered by heat in an un-isolated area or a system failure.

Correct: At the speed for minimum total drag, the parasitic drag curve and the induced drag curve intersect. At this point, the two components are equal in magnitude. This results in the highest lift-to-drag ratio and the lowest total drag for the aircraft, which is the most efficient point for endurance in a jet aircraft.

Correct: In modern aircraft engines, the oil-to-fuel heat exchanger serves a dual purpose. It uses the relatively cool fuel as a heat sink to remove excess heat from the engine oil, ensuring the oil remains within its operating temperature range. Concurrently, the heat transferred to the fuel raises its temperature above the freezing point of any entrained water, which prevents ice from clogging the fuel filters or fuel control units, a critical safety requirement under Federal Aviation Administration (FAA) certification standards.

Correct: In an oleo-pneumatic strut, the hydraulic fluid is forced through a small hole called a metering orifice during compression. This process converts kinetic energy into heat, effectively damping the landing impact and preventing the aircraft from bouncing.

Correct: In a hydromechanical FCU, the acceleration schedule is typically controlled by sensing compressor discharge pressure. This ensures that the fuel flow increases only at a rate the compressor can support without stalling, maintaining the proper air-to-fuel ratio during the transient period.

Correct: Carbon fiber is a highly noble material that is electrically conductive, creating a significant galvanic potential when in contact with aluminum alloys. In the presence of moisture, which acts as an electrolyte, this setup forms a galvanic cell where the aluminum skin serves as the anode and undergoes rapid corrosive deterioration. Federal Aviation Administration (FAA) standards require the use of an insulating barrier, such as a layer of fiberglass or a sealant, to prevent this electrochemical reaction.

Correct: The Critical Mach Number is the lowest free-stream Mach number at which the local velocity at any point on the aircraft reaches the speed of sound. This is a fundamental aerodynamic threshold in high-speed flight.

Correct: In the region of reversed command, the aircraft is flying at an airspeed slower than the speed for minimum power. In this regime, induced drag is the dominant component of total drag. As the pilot increases airspeed toward the minimum power point, the substantial decrease in induced drag more than offsets the minor increase in parasite drag. Consequently, the total power required to maintain level flight actually decreases as the aircraft speeds up, until the point of minimum power is reached.

Incorrect: The strategy of assuming power required increases when accelerating in this region is incorrect because it describes the ‘front side’ of the curve where parasite drag is the primary factor. Simply conducting an analysis based on the maximum lift-to-drag ratio is misleading, as the point of minimum drag does not coincide with the point of minimum power required. Focusing only on propulsive efficiency gains ignores the fundamental aerodynamic drag components that define the shape of the power required curve in the region of reversed command.

Takeaway: In the region of reversed command, increasing airspeed reduces power required because the drop in induced drag outweighs parasite drag increases.