An APU Quiz For All Aspiring Pilots And Plan Technicians Out There!

During the two-minute period during shutdown of the APU, you are waiting for the APU to stabilize. This means that all the systems and components of the APU need to reach a stable state before it can be safely shut down. This ensures that all the processes and functions of the APU have completed and there are no remaining tasks or operations that could be disrupted by the shutdown.

The correct answer, 1C-130H-2-49JG-00-1-1, is the technical order that covers the APU and its operation.

The boost pump must be turned on when operating the APU with less than 2,000 pounds of fuel in the #2 tank. This is necessary to ensure a consistent fuel supply to the APU, as the boost pump helps to maintain adequate fuel pressure and prevent fuel starvation. Without the boost pump, there is a risk of the APU losing power and shutting down due to insufficient fuel supply.

The minimum DC voltage for the aircraft's batteries is 21. This means that the batteries should have a voltage of at least 21 volts to operate effectively in the aircraft.

Holding the agent discharge switch to #1 or #2 position for more than two seconds during emergency shutdown procedures can be dangerous if there is a fire. This is because the agent discharge switch is used to release fire suppression agents, such as foam or gas, to extinguish the fire. If the switch is held for too long, it may lead to an excessive discharge of the agent, potentially causing more harm or spreading the fire. Therefore, it is important to follow the recommended time limit and release the switch promptly during emergency shutdown procedures.

The APU fire is detected by a steady fire warning light and a steady light in the T-Handle. This indicates that there is a fire in the APU and immediate action needs to be taken to address the situation. The steady lights in both the fire warning light and the T-Handle indicate a continuous and serious issue that requires attention.

The correct answer is 6 US quarts. The APU (Auxiliary Power Unit) oil system holds approximately 6 US quarts of oil.

The APU starter duty cycle refers to the time interval during which the APU starter is activated and the time interval during which it is deactivated. In this case, the correct answer is "1 minute on and 4 minutes off," indicating that the APU starter is turned on for 1 minute and then turned off for 4 minutes before being turned on again. This cycle is repeated to ensure proper functioning and prevent overheating or excessive wear of the APU starter.

During APU starting, the start light indicates that the APU is in the process of starting up. At 35% RPM, the APU has reached a sufficient speed for it to continue running without assistance. Therefore, the start light goes out at this point, indicating that the APU has successfully started and is running smoothly.

At 95% RPM during APU starting, the on-speed light comes on. This indicates that the APU has reached its optimal speed for operation.

Two mechanics are required to operate the APU. The APU, or Auxiliary Power Unit, is a device that provides power to an aircraft when the main engines are not running. It is responsible for starting the main engines, providing electrical power, and operating various systems on the aircraft. Due to the complexity of these tasks, it requires two mechanics to ensure proper operation and maintenance of the APU.

The area around the APU inlet door should be inspected for ice, general APU condition, and foreign objects. Ice can pose a risk to the APU's performance and should be removed. Inspecting the general APU condition ensures that it is functioning properly and any issues can be addressed. Foreign objects, such as debris or loose parts, can also affect the APU's operation and should be removed to prevent damage. Therefore, all of the above options should be considered during the inspection of the APU inlet door area.

The APU (Auxiliary Power Unit) is responsible for providing bleed air for engine starting and ground operations. Bleed air is used to start the aircraft's engines and also for various ground operations. It is not used for providing hydraulic pressure or electrical power, as stated in the other options.

Holding the AGENT DISCHARGE switch for more than two seconds may cause the fire extinguisher circuit breaker to trip. This implies that there is a safety mechanism in place to prevent the circuit from being overloaded or damaged if the switch is held for too long. It is important to release the switch within the specified time limit to avoid any potential issues.

Before pressurizing the bleed air manifold, it is important to clear the propeller area. This is necessary to ensure the safety of personnel and prevent any potential damage to the aircraft or surrounding objects. By clearing the propeller area, any objects or individuals that may be in the way of the propeller's rotation are removed, reducing the risk of accidents or damage.

Draining the fuel strainer sump prior to the first start of the day helps to ensure that the APU fuel shut-off valve is in the closed position. This is important because if the fuel shut-off valve is left open, it can lead to fuel leakage and potential hazards. By draining the fuel strainer sump, any remaining fuel in the system is removed, indicating that the shut-off valve is closed and preventing any fuel from flowing into the APU during start-up.

If the time of the pressure drop in the bleed air pressure ducts is 8.5 seconds or greater, it is considered normal and within limits. Therefore, there is no need to take any action or make any changes as it is not indicative of a problem or malfunction.

The bleed air manifold pressure gauge is located near the Navigator's control station.

UHF (Ultra High Frequency) radio is typically used for emergency communications. UHF radios have a shorter wavelength and higher frequency, allowing for better signal propagation in urban areas and indoors. They are commonly used by emergency services such as police, fire departments, and medical services to communicate during emergencies. UHF radios also offer better range and clearer audio quality, making them suitable for reliable and effective communication in emergency situations.

The quantity of the APU oil system and tank is 6 US Quarts.

The start light should go out within one minute.

If the start light doesn't go out within its specified time, the APU will be shut down and allowed to cool for four minutes.

The APU (Auxiliary Power Unit) is a device in an aircraft that provides power for various functions when the main engines are not running. If the RPM (Revolutions Per Minute) of the APU exceeds 110%, it will trigger the shutdown mechanism, and there is a possibility of it re-lighting with a loud bang. This indicates that exceeding 110% RPM is the threshold at which the APU may experience a dangerous situation, leading to its shutdown and potential damage.

If the APU fire warning system is not operating properly, it is not safe to operate the APU. The fire warning system is designed to detect any potential fire hazards in the APU, and if it is not functioning correctly, there is a risk of fire that may go undetected. Therefore, it is important to not operate the APU until the fire warning system is repaired or replaced to ensure the safety of the aircraft and its occupants.

When operating the APU from battery power only, it is essential to turn on the APU generator as soon as possible to avoid depleting the aircraft battery. The APU generator will provide electrical power to the aircraft systems, reducing the reliance on the battery and preventing it from draining completely. This is important to maintain the battery's charge and ensure that it is available for other critical functions or emergencies.

When the APU (Auxiliary Power Unit) is operating, hearing protection is required for all personnel in the vicinity of the airplane. This is because the APU generates a significant amount of noise which can be harmful to hearing. Therefore, to ensure the safety and well-being of everyone near the airplane, it is necessary for all personnel to wear hearing protection in such situations.

The correct answer is that the propellers may rotate if an engine start valve has failed in the open position. This is because when the engine start valve is open, it allows air to flow into the engine and start the combustion process. If this valve fails to close properly, it can result in the continuous flow of air, causing the propellers to rotate even when the engines are not intended to be running. This can be dangerous if there are personnel or equipment in the propeller area, as it can lead to accidents or damage.

When the engine fire test switch is placed to test and verify, the correct answer states that the FIRE warning light and the warning light in the APU fire control handle come on. This indicates that the fire warning system is functioning properly and is able to detect and indicate a fire in the engine or APU. The activation of both warning lights provides a clear visual indication to the pilot that there is a potential fire hazard and appropriate actions need to be taken to address the situation.

If the isolated DC power is interrupted while the APU is operating, the correct action to take is to place the APU control switch to stop. This is the appropriate response to ensure the safety and proper functioning of the APU.

When performing a bleed air pressure check, it is important to start timing when the pressure drops to 30 PSI. This is because 30 PSI is a significant drop in pressure and indicates that there may be an issue with the system. Starting the timing at this point allows for accurate monitoring and troubleshooting of the bleed air system.

During the bleed air pressure check, the end timing should be marked when the pressure drops to 15 PSI. This indicates that the system has been properly pressurized and can maintain the required pressure. A drop in pressure below this level may indicate a leak or malfunction in the system, requiring further inspection and maintenance.

The APU system includes various components such as the APU, APU door, APU control, APU indicating, starting system, exhaust system, and oil supply subsystems. These components work together to provide the necessary power and functions of the APU. The starting system allows the APU to be started, the exhaust system helps in expelling the waste gases produced by the APU, and the oil supply subsystem ensures that the APU is properly lubricated for smooth operation.

The normal controls for the APU are located on the overhead control panel in the flight station. This is where the pilot and co-pilot have access to various controls and switches for the aircraft systems, including the APU. The overhead control panel is easily accessible and allows for convenient operation of the APU during flight.

The explanation for the given correct answer is that the start light and on speed light are indeed located on the APU control panel. This suggests that when the APU (Auxiliary Power Unit) is being started, the start light will indicate the process, and the on speed light will indicate when the APU has reached the required speed for operation. Therefore, the statement "The start light and on speed light are located on the APU control panel" is true.

Before operating the APU, it is important to read and understand the emergency shutdown procedures. These procedures provide critical instructions on how to safely shut down the APU in case of an emergency or malfunction. By familiarizing oneself with these procedures, operators can ensure that they are prepared to handle any potential issues that may arise during APU operation, thereby ensuring the safety of the aircraft and its occupants.

Frost is acceptable on the inlet screen while operating the APU because it indicates that the APU is functioning properly and is drawing in the necessary air for combustion. The frost forms due to the cold temperature of the air being drawn into the APU, and it does not pose any risk or hinder the operation of the APU. Therefore, it is considered acceptable and normal for frost to be present on the inlet screen while the APU is running.

Failure to let the APU wind down for 4 minutes between starts could cause starter damage. This is because the starter is responsible for initiating the APU's startup process by rotating the turbine. If the APU is not allowed to wind down completely before starting it again, the starter may be subjected to excessive heat and stress, leading to potential damage.

Before pressurizing the bleed air manifold, it is necessary to turn off the air conditioning master switch. This is because the air conditioning system uses bleed air from the manifold, and pressurizing the manifold while the switch is on could cause damage to the system. Therefore, turning off the air conditioning master switch ensures that the system is not affected during the pressurization process.

Before starting the APU (Auxiliary Power Unit), it is necessary to check the setting of the aircraft cargo door and ramp controls. This is important to ensure the safety and proper functioning of the aircraft. By checking these controls, the pilot or ground crew can ensure that the cargo door is securely closed and the ramp is in the correct position. Failure to do so could result in damage to the aircraft or potential hazards during the APU start-up process. Therefore, the statement "Prior to starting the APU you have to check the setting of the aircraft cargo door and ramp controls" is true.

To run the APU, all five fire handles must be pushed in. This means that each of the fire handles must be activated or engaged in order for the APU to start functioning. This is likely a safety measure to ensure that all potential fire hazards are properly addressed before starting the APU.

When operating an APU (Auxiliary Power Unit), it is necessary to perform a radio check. This check is done to ensure that the radio communication system is functioning properly and can be used for communication purposes. By performing a radio check, the operator can verify that the APU's radio is transmitting and receiving signals effectively, allowing for clear and reliable communication with other parties.

If an engine start valve fails in the open position while pressurizing the bleed air manifold, it can cause the propellers to rotate. This is because the bleed air manifold supplies air to the propellers, and if the valve is stuck open, the pressurized air will cause the propellers to rotate.

To run the APU (Auxiliary Power Unit), there is no requirement for at least 1500 pounds of fuel in any of the main tanks. This statement is false as it implies a specific fuel quantity requirement, which is not necessary for operating the APU.

If the start light does not go out within one minute during startup, it is recommended to place the control switch to stop. This implies that if the start light remains on for more than one minute, it indicates a potential issue or malfunction in the startup process. Therefore, the correct answer is true, indicating that it is necessary to take action and stop the startup process if the start light does not go out within one minute.

The given statement is true. It states that during the start, the on speed light comes on within 35 seconds after the start light comes on. This means that after the start light is turned on, the on speed light will also be turned on within 35 seconds.

In order to start the APU (Auxiliary Power Unit), the battery needs to be turned on and the bus tie switch needs to be tied. This is because the APU requires power from the battery to start, and the bus tie switch connects the APU to the aircraft's electrical system. Therefore, both conditions must be met for the APU to be started.

The given statement is true because it states that the bleed air pressure drops from 30 to 15 PSI over time. This implies that there is a decrease in pressure, which is a common occurrence in systems that use bleed air. Bleed air is typically used in aircraft systems to power various components, and a drop in pressure can indicate a loss of power or potential issues with the system. Therefore, the statement is accurate and true.

The correct answer is "Aft of the APU in the left wheel well forward fairing." This means that the APU oil tank is located behind the APU (Auxiliary Power Unit) in the left wheel well forward fairing.

Step three of the emergency shutdown procedure is to request the fire department assistance. This is because in case of a fire or any other emergency situation, it is crucial to involve the fire department as they have the necessary expertise and equipment to handle such situations effectively. Their assistance can help ensure the safety of individuals and property, and minimize the damage caused by the emergency.

Before operating the APU or applying electrical power to the aircraft, the AFTO form781A must be reviewed to ensure no unsafe conditions exist. This form is used for the inspection and maintenance of aerospace vehicles and equipment, and reviewing it helps to identify any potential issues or hazards that could compromise the safety of the aircraft.