snowy squirrel wrote:

John wrote:

Recently at SJU I saw an IB A340-600 arrive from Madrid that left all
four engines running during the 2 hours that it was at the gate before
continuing to Santo Domingo.

If you could see the engines turning, it means that they were shut off and
just slowly turning due to wind.

It would be very hard for maintenance personel to get near the aircraft with
all 4 engines running. And I suspect extremely hazardous (if not illegal) to
refuel while engines are running.

It is far more likely that what you saw were just engines turning slowly due
to wind.

There are situations where engines on one side are left running in extreme
cold arctic conditions, and all passenger, cargo, fuel is handled from the
other side. This is to ensure that at least one engine is available to
generate sufficient power to restart the second engine.

Nope, those four fans were running at a pretty good clip. No wind
involved there. Besides, with the size of those things, it would take
a hurricane to keep them turning for two hours.