Before you take off in an aircraft, you need to make sure that the electrical system is working properly. The electrical system powers essential instruments, lights, radios, and other devices that are vital for safe and efficient flight. In this article, you will learn how to check the aircraft's electrical system before takeoff, following a simple and practical procedure.
The battery is the primary source of electrical power for the aircraft when the engine is not running, as well as a backup in case of a generator or alternator failure. To check the battery, you must first turn on the master switch and observe the battery voltage on the voltmeter or multifunction display. This should be above 12 volts for a 12-volt system or 24 volts for a 24-volt system. Then, turn on the landing light and observe the battery voltage again; it should drop slightly but not below 10 volts for a 12-volt system or 20 volts for a 24-volt system. Finally, turn off the landing light and master switch.
Ensuring the aircraft's electrical system is vital for a safe takeoff. Checking the battery involves verifying voltage, capacity, and charge. Inspecting connections for tightness and corrosion is crucial. Testing emergency power sources and backup systems adds redundancy. Assessing cockpit instrument functionality, including warning lights, contributes to electrical system health. Pilots should monitor generator performance, confirming proper voltage and load distribution. Regular maintenance, adherence to checklists, and addressing discrepancies promptly enhance overall electrical system reliability, crucial for a seamless takeoff and inflight operations.
The generator or alternator is the main source of electrical power for the aircraft when the engine is running. It converts mechanical energy from the engine into electrical energy and charges the battery. To check the generator or alternator, start the engine and observe the battery voltage on the voltmeter or the multifunction display. It should increase to around 14 volts for a 12-volt system or 28 volts for a 24-volt system. Then, turn on the avionics master switch and some electrical devices, such as the radio, navigation lights, and pitot heat. Observe the ammeter or loadmeter which shows the current or percentage of electrical load on the system; it should not exceed the maximum limit specified in the aircraft manual. Finally, turn off all electrical devices and avionics master switch.
Circuit breakers are safety devices that protect the electrical system from overloads and short circuits by automatically disconnecting power from a circuit when the current exceeds a certain value. To check the circuit breakers, you need to locate the panel, which is usually on the instrument panel or side wall of the cockpit and has labels for each circuit and values for each breaker. Visually inspect the circuit breakers to make sure none of them are popped out or tripped; if they are, identify the cause of the problem and reset them by pushing them in. Additionally, test the circuit breakers by pulling them out one by one and verifying that the corresponding electrical device stops working. Then push them in and verify that the device resumes working.
Fuses are similar to circuit breakers, but they cannot be reset. If the current exceeds a certain value, the fuse melts and interrupts the power from a circuit. To check the fuses, first you need to locate the fuse panel, which is usually on the instrument panel or side wall of the cockpit. It should have labels for each circuit and values for each fuse. Then, visually inspect the fuses and make sure none of them are blown or burned. If they are, replace them with spares of the same value and type. Lastly, test the fuses by removing them one by one and verifying that the corresponding electrical device stops working. Once you have inserted them back, verify that the device resumes working.
To check the switches and indicators of the electrical system, you should first locate them on the instrument panel or overhead panel. These should have labels for their functions and positions. You should then test the switches by turning them on and off to verify that the electrical devices respond accordingly. For example, the landing light switch should turn on and off the landing light, and the generator or alternator switch should turn on and off the generator or alternator. Lastly, you should test the indicators by observing their readings to ensure they match the expected values or conditions. For instance, the battery voltage indicator should show the battery voltage, and the generator or alternator warning light should be off when the generator or alternator is working.
To check the wires and connectors that carry and connect the electrical power from the source to the load, you need to first locate them, which are usually behind the instrument panel or under the floor panels. They should have labels for their colors and functions. Then, visually inspect them and make sure none of them are loose, frayed, corroded, or damaged. If they are, secure, clean, or repair them as needed. Finally, test the wires and connectors by gently wiggling them and verifying that there is no interruption or fluctuation in the electrical power or the device operation. If there is, tighten, replace, or solder them as needed.