What component will fail if the generator fails while the bus tie is closed and under normal operation?

When a generator fails while the bus tie is closed and the system is under normal operation, the air conditioner is more likely to be impacted due to its reliance on electrical power generated by the generator. The air conditioning system typically requires a substantial amount of electrical power to operate, and if the generator cannot provide that power, the air conditioner will cease to function effectively.

In contrast, other components like the fuel pump, navigation lights, and communication radios may still operate or are designed with separate fail safes and systems to remain functional even if one generator fails. The fuel pump, for example, is often powered directly from the aircraft's fuel system, while navigation lights and communication radios might have redundancy in their power supplies or receive power from other sources that do not solely depend on the generator. Thus, the air conditioner is the most directly affected component in this context when the generator fails.