One sits underneath the cockpit in a compartment known as the forward electrical equipmentbay, which was where Wednesday's malfunction occurred, and a second in the aft bay under the wings, which was the site of last week's fire in Boston.
Officials had said they were examining the electrical system broadly, but while earlier incidents involved components in the aft electrical equipmentbay, located behind the wings, Wednesday's involved a forwardbay that until now had been largely free from scrutiny.