When external power is used, what must be ensured?

When external power is used, what must be ensured?

• A. It is sufficient for the start and can be safely disconnected
• B. It is always on
• C. It must be from the main aircraft power
• D. It should be left connected until shutdown

Answer: (A)

When external power is used, the essential idea is that the power source only needs to be capable of delivering enough power to perform the start, and it can be safely disconnected once the start sequence has begun or completed. This means the external supply should meet the required voltage and current for the start without being relied on beyond that point. Disconnecting after the start ensures you don’t leave the cart or source feeding loads unnecessarily, reduces the risk of backfeeding into the external source, and avoids keeping the external system energized during subsequent flight operations. The other options aren’t correct because external power is not intended to stay on indefinitely; it’s a temporary aid to start and power systems on the ground. It doesn’t have to come from the main aircraft power source, since external power is, by definition, an outside supply. And it should not be left connected until shutdown, as you want to transition to aircraft-side power once the aircraft is ready to operate.

When external power is used, the essential idea is that the power source only needs to be capable of delivering enough power to perform the start, and it can be safely disconnected once the start sequence has begun or completed. This means the external supply should meet the required voltage and current for the start without being relied on beyond that point. Disconnecting after the start ensures you don’t leave the cart or source feeding loads unnecessarily, reduces the risk of backfeeding into the external source, and avoids keeping the external system energized during subsequent flight operations.

The other options aren’t correct because external power is not intended to stay on indefinitely; it’s a temporary aid to start and power systems on the ground. It doesn’t have to come from the main aircraft power source, since external power is, by definition, an outside supply. And it should not be left connected until shutdown, as you want to transition to aircraft-side power once the aircraft is ready to operate.