Which situation interrupts the E-PBIT?

The situation that interrupts the E-PBIT (Electrical Power Built-In Test) is an AC power interruption. The E-PBIT is a critical self-diagnostic function that checks the electrical systems of the aircraft to ensure they are operating correctly. When there is an interruption in AC power, the system loses the necessary electrical supply to perform its tests and diagnostics. Consequently, this interruption halts the E-PBIT process, preventing it from completing its checks and potentially compromising the ability to assess the system's health.

In contrast, the other situations listed do not directly cause an interruption of the E-PBIT. While flight control movement could momentarily affect some systems, it does not directly interrupt the testing process. The status of hydraulic pumps being off may influence the aircraft's systems, but it is not related to the functionality of the E-PBIT in the same manner as an AC power loss. Likewise, pitch control failure impacts flight dynamics but does not disrupt the E-PBIT operation. Thus, the critical link between AC power and the E-PBIT's ability to function successfully highlights why an AC power interruption is the correct answer.