Which statement about the nonessential bus is true?

• A. It powers cabin lighting and entertainment, which can be shed when power is limited
• B. It powers flight control computers
• C. It powers essential flight instruments
• D. It powers the standby battery

Answer: (A)

Nonessential electrical loads are those not needed to keep the aircraft safely flying, and they can be shed to conserve power when power is limited. Cabin lighting and passenger entertainment are classic examples of loads placed on the nonessential bus because turning them off doesn’t affect flight safety or control.

In contrast, flight control computers and essential flight instruments rely on the essential power bus to stay powered, even during electrical limits, so they aren’t supported by the nonessential bus. The standby battery is an independent source dedicated to keeping standby instruments alive if primary power fails, not something that is powered by the nonessential bus.

So, the statement that the nonessential bus powers cabin lighting and entertainment and can be shed when power is limited is the correct interpretation.