What is necessary when operating two aircraft AC generators in parallel?

When operating two aircraft AC generators in parallel, maintaining equal frequency and voltage is crucial. This ensures that both generators can share the electrical load evenly without causing any fluctuations or disruptions in the system. If the frequencies or voltages are not equal, it can lead to serious operational issues, such as voltage surges, generator instability, or even damage to the generators or connected systems.

Additionally, proper synchronization is also important before connecting the generators. However, the necessity for this synchronization directly serves the overall goal of ensuring equal frequency and voltage. If both generators are not synchronized (which includes matching their frequencies, voltages, and phase angles), it could cause one generator to "fight" against the other, leading to potential mechanical and electrical failures.

Overall, while connection to a common ground and regular maintenance checks are important aspects of generator operation, they do not directly address the core requirement of ensuring both generators can operate in parallel safely and efficiently. Thus, the emphasis on equal frequency and voltage is fundamental for the proper functioning of aircraft AC generators.