(Reuters) - The U.S. Federal Aviation Administration said it would ask the operators of Boeing Co's model 787 airplanes to deactivate the plane's electrical power system periodically.
The FAA said the new airworthiness directive was prompted by the determination that power control units on a model 787 airplane could shut down power generators if they are powered continuously for 248 days.
Sudden loss of power could result in the aircraft going out of control, the directive noted.
Boeing is developing a software upgrade to counter the problem. FAA estimates that this directive affects 28 airplanes of U.S. registry.
In November last year, the FAA had proposed a fix for the 787 model after "numerous reports of failures of proximity sensors" on the plane's wings.
Boeing delivered 30 of its 787 planes worldwide in the first quarter of 2015.
(Reporting by Krishna Chaithanya in Bengaluru; Editing by Leslie Adler)