EASA has issued an airworthiness directive (AD) in response to the runaway trim incident that temporarily grounded the Falcon 7X fleet in May. Most of the fleet was shortly returned to service.
The new AD, developed in conjunction with Dassault, calls for a modification of the fly-by-wire system to allow for earlier failure detection and quicker reversion of the horizontal stabilizer trim system.
AD 2011-0169 is a follow up to an earlier AD that allowed the majority of the Falcon 7X fleet to resume flight operations in July.
Operators need to comply with the AD within approximately a year, depending on what work has already been performed on the airplane. While compliance with this AD “restores the full original certified flight envelope of the aeroplane,” EASA deems both of the Falcon 7X ADs that have resulted from the runaway trim incident to be interim measures.
It’s expected that the FAA will follow suit with a directive based on the European authority's latest guidance.
Dassault calls its decision to ground the fleet a conservative decision and points out that there has been only one reported trim event in the 7X’s five-year operational history, adding that the flight envelope control laws on that airplane continued to operate normally throughout the event and that it resumed normal flight and an uneventful landing after the trim event.