Will Become The Only Commercial Airliner To Feature Hinged Design

The FAA has certified Boeing's design for folding wingtips on the 777X airliner that will allow the aircraft to operate at existing airport gates.

The "special conditions" were approved Friday by the FAA. In a notice posted in the Federal Register, the FAA said that the Boeing Model 777-8 and 777-9 airplanes will incorporate CFRP wings with folding wingtips. Boeing will incorporate this on-ground wingtip-fold capability to reduce the wingspan from 235 to 212 feet when folded. These folding wingtips comply with Code E gate [1] compatibility when folded during ground operations.

This wing-folding feature will be operable on the ground only. Boeing has no plan to carry fuel in the folding sections of the wings.

Boeing has determined that a catastrophic event could occur if the Model 777-8 and 777-9 airplane wingtips are not properly positioned and secured for takeoff and during flight. In service, numerous takeoff operations with improper airplane configurations have occurred due to failures of the takeoff warning systems, or inadvertent crew actions.

For these special conditions, a parallel is drawn between taking off with gust locks engaged and taking off with the wingtips folded, as either condition could result in a catastrophic event. Consequently, the FAA has determined that the level of safety in protecting a misconfigured airplane from takeoff with wingtips folded should be the same as taking off with the gust locks engaged. Therefore, the applicant must show that such an event is extremely improbable, must not result from a single failure, and that appropriate alerting must be provided for the crew to manage unsafe system-operating conditions. In addition, the applicant must ensure that the wingtips are properly secured during ground operations to protect ground personnel against bodily injury.

This action affects only a certain novel or unusual design feature on one model series of airplanes. It is not a rule of general applicability.

(Source: Federal register. Image from file)

FMI: www.federalregister.gov/documents/2018/05/18/2018-10576/special-conditions-the-boeing-company-model-777-8-and-777-9-airplanes-folding-wingtips