Latest Boeing 777X Delay Driven By EASA’s Concerns

Boeing 777X second test flight
Credit: Boeing

Regulatory scrutiny that will add at least a year to Boeing’s 777X certification program goes beyond the flight-control system and stems primarily from concerns being voiced by EASA, multiple sources confirmed to Aviation Week. 

Boeing CEO Dave Calhoun revealed Jan. 27 that the 777-9 will not enter service until late 2023 at least—adding a year to a schedule that has already been stretched out several times. Citing “feedback” from “global regulators,” Calhoun confirmed Boeing will “implement certain modifications to the aircraft design,” including “firmware and hardware changes to the actuator-control electronics.” 

One senior airline executive with knowledge of the situation characterizes EASA’s review as having a broad perspective, not just zeroing in on a few systems. The requests are “so significant that the program will be delayed by several years, leaving Boeing no choice but to revise its entry-into-service target,” the executive said. 

EASA’s watch-list has multiple items, led by systems that may lack redundancy, safety-critical systems and—as expected—anything that was changed substantially compared to the 777-300ER, multiple sources said. Change requests include parts of the electronic flight control system, which EASA believes needs enhanced redundancy and failure protection. Components such as the folding wingtips also will be subject to detailed review beyond what the U.S. FAA has conducted.  

“We knew that certification was going to be an issue given the MAX saga,” the CEO of one 777X customer said. “It was inevitable that the 777X would come into the crosshairs. The same certification methodologies employed by Boeing on the MAX were used on the 777X and hence the detailed scrutiny by the likes of EASA.”  

While EASA has several concerns linked to 777X system architecture, a primary one focuses on the potential for single points of failure in the fly-by-wire flight-control system, multiple sources said. Boeing fly-by-wire designs traditionally employ triple redundancy architectures designed to survive at least two failures. Airbus aircraft, such as the A320, use dissimilar computers running dissimilar software packages.  

One regulatory official said EASA’s familiarity and comfort with the Airbus approach—combined with concerns amplified during the 737 MAX review that included an EASA-led push to add flight-control system redundancy—are contributing to the European regulator’s concerns on the 777X. While the FAA acknowledges both approaches can work, the regulator points to Boeing’s success with its approach, and the possibility of introducing more failure scenarios when variants of the same system are used, the regulatory official said. 

Among the issues Boeing faces on the 777X—and were spotlighted in the 737 MAX fallout from two fatal accidents and a 21-month global grounding—are regulatory nuances that govern derivative aircraft. Boeing’s 2015 777 type certificate amendment application requests adding the 777-9 as a derivate of the 777-300ER, which the FAA approved in 2004. Rule changes introduced by the FAA since the 777-300ER’s approval include Part 25.1302, which links flight deck and system design to flight-crew performance, with an eye on minimizing design-induced errors. 

The rule will apply to the 777-9, but only in areas where the new design differs from the 777-300ER, such as operational issues linked to the 777-9’s folding wingtips. Unless Boeing opts to apply the rule to all aspects of the 777-9 systems-flight crew interface, which it is not required to do, some assumptions will lack real-world validation, since the regulations came after the 777-300ER. But EASA is expected to carefully scrutinize such issues, paying close attention to anything related to fight deck human factors and pilot assumptions.  

“There is no more full grandfathering from the 777-300ER to the [777X], largely as a fallout of the MAX disaster,” the senior airline executive said.  

Bilateral agreements that have established protocol—in this case, the FAA approves the aircraft as the country of design, and others, such as EASA, largely validate the U.S. agency’s work—remain in force. But the MAX fallout, which included EASA and Transport Canada taking different positions on several issues, has weakened the FAA’s stature, several sources said. Meanwhile, the U.S. agency is facing new requirements from lawmakers to change aspects of its certification process.

No customers have asked Boeing to review the 777X, several sources said. Two airline sources acknowledge that, given the global travel downturn, 777X delivery delays are more benefit than problem.

Officially, EASA is saying little beyond acknowledging it plans to take on larger roles in certification programs, including the 777X.

“EASA has said that it will increase its scrutiny on the flight-control system on the 777X, and we have started the discussions with the FAA and Boeing on this,” EASA said. “We are not commenting in detail on the scope of our activities, but we will indeed be conducting a more in-depth review of the aircraft-critical changes as part of our lessons learned from the 737 MAX. We will be following a thorough process to ensure the safety of the aircraft.”  


Sean Broderick

Senior Air Transport & Safety Editor Sean Broderick covers aviation safety, MRO, and the airline business from Aviation Week Network's Washington, D.C. office.

Jens Flottau

Based in Frankfurt, Germany, Jens is executive editor and leads Aviation Week Network’s global team of journalists covering commercial aviation.

Guy Norris

Guy is a Senior Editor for Aviation Week, covering technology and propulsion. He is based in Colorado Springs.


Pretty sure that the 777 flight control system has different processors running dissimilar software, too. It was essential to achieve the 10 to the minus 9 failure requirements, if memory serves.
EASA is imposing Airbus design philosophy into the 777X.

Base 777 aircraft is one of the safest airliner so far, even compared to Airbus 330/340 contemporary.

Boeing is now safety conscious or else they will lose $$$billions again