EASA has spelled out its requirements for allowing the Boeing 737 Max to return to service, indicating that it may lift its grounding in mid-January. Less than a week after FAA gave Boeing the go-ahead to return the narrowbody to service, the European agency late on Tuesday published a proposed airworthiness directive (AD), inviting industry comment by December 20. This stage will be followed by a review process before a final AD is published.
The proposed requirements from EASA are close to those included in the airworthiness directive Boeing published last week. However, the European AD does include some additional items, such as changes to the stick-shaker stall warning procedure to require circuit breaker deactivation, as well as a ban on RNP-AR approaches and an increased minimum height for single-channel autopilot operations.
EASA grounded the 737 Max on March 12, 2019, following two fatal accidents resulting in the loss of 346 lives. In a statement, the agency said it has had 20 technical experts working on the case for the past 20 months to prepare the proposed requirements.
According to EASA executive director Patrick Ky, his officials made an early decision to review the entire 737 Max flight control system, rather than limiting its focus to the failures in the aircraft’s maneuvering characteristics augmentation system (MCAS), which was identified as a primary cause of both accidents. The agency considered all aspects of the aircraft design that could influence how the flight controls were used in service.
“This led, for example, to a deeper study of the wiring installation, which resulted in a change that is now also mandated in the proposed airworthiness directive,” Ky explained. “We also pushed the aircraft to its limits during flight tests, assessed the behavior of the aircraft in failure scenarios, and could confirm that the aircraft is stable and has no tendency to pitch-up even without the MCAS.”
EASA also focused on human factors issues, such as the alerts provided for pilots in the event of system failures, as well as all procedures and training. The lengthy investigation following the two accidents found that some pilots were not even aware that the MCAS equipment was on the aircraft and that no caution light appeared to make the pilots of the two crashed aircraft aware that the angle-of-attack sensor was faulty.
In addition to the proposed aircraft design changes, EASA also will require mandatory training to ensure that pilots fully understand all aspects of the 737 Max’s flight control system. This will involve additional simulator training.
Last week, Boeing released an extensive plan covering the return-to-service process for hundreds of aircraft, starting with those in the U.S. In March 2020, the airframer resumed production of the model at a low rate.