What needs to be checked when the low volt annunciator is on below 1000 RPM?

When the low volt annunciator is illuminated below 1000 RPM, the primary concern is often related to the electrical systems of the aircraft. The correct action in this scenario involves increasing the engine RPM to 1000, as this helps to establish a higher engine speed, which in turn can assist in the operation of the alternator or generator that charges the aircraft's electrical system.

At lower RPMs, the electrical output may not be sufficient to support all systems, leading to the low voltage condition indicated by the annunciator. By increasing the RPM, the alternator may be able to produce enough voltage to rectify the situation, ensuring that electrical systems have the proper operational levels.

The other options do not address the immediate need to restore electrical output through engine management. Turning off all systems might lead to a total loss of power for critical instruments, while conducting an emergency landing may be unnecessary if the issue can be resolved simply by increasing the RPM. Notifying the control tower may not be relevant at this stage, as the focus should be on correcting the low voltage condition.