The Federal Aviation Administration (FAA) is proposing mandatory fan cowl modifications on certain Boeing 787 Dreamliners after Boeing found that debris from a serious failure of one engine could damage critical components on the other and potentially cause both engines to shut down in flight.
The proposed airworthiness directive (AD) applies to certain Boeing 787-8, 787-9 and 787-10 aircraft powered by Rolls-Royce Trent 1000 engines. The FAA estimates 22 aircraft on the US registry would be affected.
The problem centers on the left fan cowl of the aircraft’s right engine. Boeing determined that the existing protection does not adequately shield several oil lines from debris that could be released by an uncontained rotor failure in the left engine.
The FAA warned that debris from such a failure could damage the right engine and lead to an in-flight dual engine shutdown.
Boeing reported the problem to the FAA and developed changes to address it. The manufacturer issued a Special Attention Requirements Bulletin on February 19, 2026, outlining inspections and modifications for affected aircraft.
Under the FAA proposal, operators would have to check maintenance records or inspect the right engine’s left fan cowl to determine whether one of three affected part numbers is installed.
Aircraft with an affected fan cowl would then require modification or replacement of the part. The proposal would also prohibit operators from installing affected fan cowls on aircraft that do not already have them.
The FAA estimates the initial records check or inspection would require three work hours per aircraft at a cost of $255, or $5,610 for the 22 US-registered aircraft covered by the proposal. The agency did not provide an estimated cost for the subsequent fan cowl modification or replacement.
The proposed rule stems from a certification issue rather than an accident or incident involving an in-service 787. The concern is whether the aircraft has enough protection if an uncontained failure in one engine sends high-energy debris toward the other.
Transport category aircraft are designed so that an uncontained engine failure does not prevent the airplane from safely completing a flight. Federal certification standards specifically account for structural damage caused by uncontained engine failures.
The proposed AD would make Boeing’s February instructions mandatory for affected US operators. Compliance times would follow those in Boeing’s requirements bulletin once a final rule takes effect.
The FAA is accepting public comments through September 21, 2026, before deciding whether to issue a final AD.