I think he means Engine Running Offload. I worked for a regional airline in Alaska for several years and under certain circumstances, we would do these. We operated the Saab 340 and our preference was always to start off of ground power. While most of our out-stations had GPU’s there were a few that didn’t. So if you pulled into say Aniak on a -30 day, the procedure was to leave the right engine running and execute what we called a “single-engine turn”.On the 340, most everything happened on the left side of the airplane to include pax boarding and accessing the cargo compartment. We would usually put someone up by the nose to keep anyone from wandering over to the right side of the airplane. None of our airplanes had APU’s and it was hard on the batteries if you did a battery start. Especially when it was cold. Certainly not a common procedure for us and I have no idea if it has anything to do with what happened here.