What must you do before folding the tail of the aircraft?

Applying battery power is essential before folding the tail of the aircraft. This procedure ensures that any electrical systems needed for the tail fold operation are operational. Typically, the mechanism that controls the folding process relies on electrical power for its actuation, meaning that without battery power, you may not be able to properly or safely execute the tail folding operation.

Additionally, having battery power allows the relevant safety systems and indicators to function, which can be crucial for confirming that the process can proceed without risking damage to the aircraft or injury to personnel. Thus, ensuring battery power is a foundational step that underlies the safe operation of the tail folding mechanism on the aircraft.