After engine shutdown, how many minutes must the batteries remain on?

After engine shutdown, how many minutes must the batteries remain on?

• A. 1 minute
• B. 3 minutes
• C. 5 minutes
• D. 10 minutes

Answer: (B)

When the engine is shut down, the electrical system shifts from generator power to battery power. The procedure requires the batteries to stay on for a set minimum time to ensure the system can sustain essential loads and to let the power distribution and standby instruments stabilize. Three minutes gives enough time to verify that critical items—like standby instruments and essential avionics—remain powered without generator input. A shorter interval wouldn’t reliably confirm that the battery can support the loads, while longer intervals exceed the stated requirement.

When the engine is shut down, the electrical system shifts from generator power to battery power. The procedure requires the batteries to stay on for a set minimum time to ensure the system can sustain essential loads and to let the power distribution and standby instruments stabilize. Three minutes gives enough time to verify that critical items—like standby instruments and essential avionics—remain powered without generator input. A shorter interval wouldn’t reliably confirm that the battery can support the loads, while longer intervals exceed the stated requirement.