The Federal Aviation Administration (FAA) is issuing a rule requiring urgent attention by operators of Boeing's 787 Dreamliner to avoid the possibility all three computer modules that manage the jet's flight-control surfaces could briefly stop working while in flight.
Operators must periodically shut and restart the electrical power on the planes, or the power to the three flight control modules. That will avoid the problem until Boeing has a permanent software fix.
In an airworthiness directive to be published Friday, the FAA said it is reacting to indications that "all three flight control modules on the 787 might simultaneously reset if continuously powered on for 22 days."
It said such a simultaneous reset in flight "could result in flight control surfaces not moving in response to flight crew inputs for a short time and consequent temporary loss of controllability."
A person with knowledge of airline practices, speaking on condition of anonymity, said it is "extremely rare" for any operator to leave the jet powered on for longer than a week.
In a statement, Boeing said the new rule mandates actions the jet maker has already recommended to 787 operators during the past two months.
"Boeing recommended that operators cycle power to flight control modules periodically to ensure overlapping resets do not occur," Boeing stated. "A permanent software fix is anticipated in the second quarter of 2017."
The FAA is mandating that the roughly 99 Dreamliners registered in the U.S. act on the directive within a week.
Foreign airlines typically follow the FAA's lead on such directives. To date, 489 Dreamliners have been delivered worldwide.