With a loss of TR 1, what pilot action is required?

When TR 1 is lost, the aircraft's electrical system has a built-in redundancy to ensure continued power supply. In this case, the essential bus (DC bus 1) will automatically be powered by TR 2, which is the second transformer rectifier. This redundancy is a crucial design feature that enhances the reliability of the aircraft's electrical system by ensuring that critical busses receive power even if one of the transformers is lost.

The automatic transfer to TR 2 means that the pilot does not need to take immediate action to restore power to DC bus 1; the system has been designed to handle such failures efficiently. This resilience is essential for the safety and operation of the aircraft, minimizing the pilot's workload in the event of a failure.

In contrast, the other choices imply actions that are not necessary in this scenario, as the system automatically compensates for the loss of TR 1 by switching to TR 2 without requiring pilot intervention.