What should be done after pulling ecb 216 in response to a BIU #1 DEGRADED message?

In the scenario where you encounter a BIU #1 DEGRADED message, one critical action is to reset the associated circuit breaker, which in this case is ecb 216. Resetting the circuit breaker is a standard procedure as it can often restore the functionality of a system that is not operating properly. In many cases, pulling the circuit breaker is intended to clear faults or anomalies within the system.

By resetting ecb 216, you are effectively attempting to reinstate normal operations of the affected system component, allowing the system to reinitialize and possibly correct the degradation issue indicated by the BIU message. This step is essential in troubleshooting because it addresses the immediate electrical anomaly that may be contributing to the degraded performance.

Following this reset, it is also prudent to monitor the system's reaction to ensure that the BIU no longer shows a degraded status. While notifying the flight crew, conducting a full system check, or shutting down the APU can be part of broader troubleshooting or safety protocols, the primary and most immediate action following the degradation message is the reset of the circuit breaker.