Electrical System, Fire Protection and Detection System

When the AC power is on the bus bars, there are no system faults, and the OVHT DET switches are in NORMAL, selecting OVHT/FIRE on the test switch will illuminate several lights. These include the Master FIRE WARNING lights, ENG1+ENG2 and APU fire switch lights, and WHEEL WELL FIRE light. Additionally, the MASTER caution lights, OVHT/DET annunciator, and the ENG+ENG OVERHEAT lights will also be illuminated.

The normal AC volts and frequency for the 2 engine driven generators and the APU generator are 115 v (+/- 5 v) and 400Hz (+/- 10 Hz).

The illumination of the "TR UNIT" light indicates that either TRU1 or TRU2 and TRU3 have failed.

After a generator drive disconnect, the drive can only be re-engaged on the ground by maintenance. This means that the drive cannot be re-engaged while the aircraft is in flight. The maintenance crew is responsible for addressing any issues with the generator drive and ensuring that it is properly re-engaged before the aircraft can continue operating. The flight crew does not have the capability to re-engage the drive themselves.

When either the fire warning or overheat light illuminates, it indicates a potential issue with the engine. In such a situation, the engine fire warning switch lock mechanism is automatically unlocked to allow the pilot to take immediate action and address the problem. This ensures that the pilot has the ability to respond quickly and effectively to any engine-related emergencies while in flight.

The correct answer indicates that when the extinguisher test switch is held in the 1 or 2 position, 3 green lights illuminate, indicating that the associated bottle discharge circuits for all 3 extinguisher bottles are normal. This means that the circuits are functioning properly and there are no issues with the discharge of the extinguisher bottles.

The illumination of the "GND Power Available" light indicates that AC ground power is connected and meets airplane power quality standards. This means that the aircraft is receiving a reliable and high-quality power supply from an external source.

The correct answer is the hot battery bus (28v DC). The hot battery bus is a direct current (DC) power source that provides electrical power to various systems on the aircraft. The APU fire extinguishing system is one of these systems and it relies on the hot battery bus to supply power for its operation. This ensures that the APU fire extinguishing system has a reliable power source to effectively extinguish any fires that may occur in the APU.

When the output from no1 IDG fails during a flight, power AC transfer bus 1 is automatically restored by transferring power from AC transfer bus 2 via the AC tie bus. This is done automatically without any manual intervention or reliance on the battery.

The switched hot battery bus will be powered by a functional battery when the battery switch is selected to ON. This means that the battery is connected to the electrical system and is providing power to the switched hot battery bus.

If a malfunction occurs in one fire loop with the OVHT DET switch in the normal position, the system is still available for the rest of the flight. This is because the defective loop is automatically removed from the system, and the remaining loop continues to function as a single loop detector.

Positioning the ground power switch to ON in this scenario will trip both engine generators and connect external power to the transfer buses. This means that the aircraft will be disconnected from its own generators and rely solely on the external power source. Additionally, the external power will be connected to the transfer buses, allowing it to power the necessary systems and equipment on the aircraft.

TRU no 2 receives its AC power from AC transfer bus 2. This means that the power is transferred from the AC transfer bus 2 to TRU no 2 for its operation.

The correct answer is 28 volts DC. This is because the question states that DC power is supplied by 3 TR units. DC stands for direct current, which means that the voltage is constant and flows in one direction. Therefore, the output voltage would also be DC. The given answer of 28 volts DC aligns with the information provided in the question.

When an Integrated Drive Generator (IDG) is lost and only one generator is operating, the loads that are initially shed include Galley bus A + B (shed from transfer bus 2). This means that the power supply to Galley bus A and Galley bus B is disconnected from transfer bus 2. This shedding of loads is necessary to balance the power supply and demand in the system and prevent overloading of the remaining generator.

The main battery charger is powered by the AC ground service bus 2.

The power source for the ENG Overheat and Fire Protection detection system is the Battery bus (28v DC). This means that the system is powered by the aircraft's battery, which provides a direct current of 28 volts. The battery bus is a common source of power for various systems in an aircraft, including critical systems like fire detection and protection. It ensures that the detection system has a reliable and independent power source to operate effectively in case of an engine overheat or fire situation.

When the standby power switch is in the AUTO position, the automatic switching to the alternate power source will occur if either AC transfer bus 1 or DC bus 1 loses power.

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The correct answer is 24 volts DC. This is because the given information states that the battery voltage is 24 volts DC. Additionally, the range is specified as 22 to 30 volts, which falls within the given voltage. Lastly, it is mentioned that the battery supplies standby power for 30 minutes, which matches the information provided.

The illumination of the "elec" light on the electrical panel indicates that a fault has been detected in the DC or standby power system. This means that there is an issue with either the DC power system or the standby power system, which could potentially cause a disruption in the electrical supply. It is important to address this fault promptly to ensure the proper functioning of the power system.

When both loops detect a fire condition, the engine fire warning will be activated. This means that both fire detection loops must independently detect a fire in order for the warning to be triggered. If only one loop detects a fire or an overheat condition, the warning will not be activated. Similarly, if both loops detect an overheat condition without a fire, the warning will not be activated.

The normal supply to the battery bus is provided by the AC ground service bus 1.