On Friday, the Federal Aviation Administration (FAA) issued an airworthiness directive (AD) about a software glitch affecting the generator control units (GCUs) in Boeing 787 Dreamliner, a twin-engine jet airliner.
The directive (PDF) details “interim action” to be taken by plane operators in order to prevent loss of alternating current (AC) electrical power due to generator control units “simultaneously going into failsafe mode.” Such conditions would only be present, however, if the plane's four main GCUs were “powered up at the same time, after 248 days of continuous power,” which could result in the generators shutting down and, potentially, “loss of control of the airplane,” the directive said.
While the manufacturer develops a GCU software update to address the safety issue, operators were ordered to deactivate electrical power on the affected airplane model before the 248-day period elapsed. The FAA estimated that the airworthiness directive will affect 28 commercial airliners of U.S. registry.
