Boeing engineers are set to design the Boeing 777x foldable wings operation to be unnoticeable as flaps tracks and thrust reversers to operators. according to Boeing’s airport planning document.
The 777X family comes in two variants of 777-8 and -9. The 777-9 will be the first model to enter into service in two years time. The main feature of the airplane is the folding wing tip (FWT).
Normal Operation
According to Boeing, The 777-9 taxis to the departure runway with the FWT(Folding Wing Tip) folded. Once passing a predetermined location that assures wingtip clearance, the flight crew will (manually) initiate the command for the FWT to extend so as to be in the takeoff configuration (extended and locked) prior to the hold-short line.
Upon landing, the FWT control logic will automatically fold the FWT after the aircraft has touched down and ground speed is below 50 kts. This ensures that the FWT will be folded before entering the parallel taxiway.
Non-Normal Condition
In the event of a non-normal FWT condition, the flight deck crew will be alerted via EICAS messaging, and the non-normal FWT operation plan will be invoked.
In the event of a high-speed rejected takeoff (RTO) scenario, the automatic fold feature is enabled. If the airplane achieves a rejected takeoff ground speed of 85 kts or above, then the FWT will automatically fold once the airplane has decelerated below 50 kts ground speed. The 85 kts threshold is the same threshold for activating RTO autobrakes and speedbrakes. Rejected takeoffs that occur below 85 kts will not trigger the auto fold function and the flight deck crew will manually fold the FWT.
Folding of the wing tips takes 20 seconds to fold upon landing.
Boeing says that FWT is a highly reliable system with built in redundancy and therefore non-normal operations are expected to be infrequent. Reliability is similar to other systems on existing 777 aircraft such as flaps, main landing gear steering, and thrust reversers.
