What indicates a properly functioning alternator in an aircraft?

A properly functioning alternator in an aircraft is indicated by stable voltage output under load. This means that despite varying demands from the electrical systems and equipment of the aircraft, the alternator consistently maintains an output voltage within the specified range. This stability ensures that essential systems, such as avionics and navigation instruments, operate effectively and without interruption.

When an alternator is subjected to load, its ability to maintain voltage indicates that it is generating enough power to meet the demands placed on it. If the voltage were to fluctuate significantly or drop under load, it would suggest that the alternator is struggling to keep up with the electrical demands, which could lead to system failures or degraded performance.

In contrast, high current draw can be a sign of excessive load or malfunction but does not necessarily indicate that the alternator is functioning properly. Visible signs of corrosion may affect the alternator’s performance over time but do not directly indicate its operational condition at a given moment. Low operational noise can be a good characteristic but does not provide a definitive measure of the alternator's effectiveness in supplying electrical power.