The Civil Aviation Administration of China (CAAC) has issued an airworthiness directive (AD) outlining aircraft-specific parameters for returning the Boeing 737 MAX to service, essentially mandating the same series of measures required by its U.S. counterparts and, in one case, European and Canadian regulators.
Modifications include updates to the model’s flight control computer and avionics display software driven directly by issues raised in the probes of two fatal accidents that led to the fleet’s worldwide grounding in March 2019. Aircraft also must undergo horizontal stabilizer trim wire modifications to correct a regulatory compliance issue discovered as part of Boeing’s broad review of the 737 MAX design during the grounding.
CAAC also opted to adopt a notable change embraced by the European Union Aviation Safety Agency and Transport Canada—approving a procedure that gives pilots the option of pulling circuit breakers to disable a nuisance stick-shaker stall warning. CAAC’s mandatory flight manual supplement, included in the directive, details the procedure, which some regulators believe is a prudent option for eliminating the distraction of a spurious warning during a possible emergency. The FAA did not include the procedure in its new 737 MAX operating parameters, concluding the risks of pilots pulling a breaker out-weigh the potential benefits.
CAAC’s return-to-service modification list includes installing colored caps on affected circuit breakers to help pilots easily identify them if needed, mirroring other regulators that adopted the procedure.
“After conducting sufficient assessment, CAAC considers the corrective actions are adequate to address this unsafe condition,” the AD said.
While the directive includes the nuisance stall-warning procedure, baseline pilot-training requirements are not discussed. They likely will mirror other regulators, which require 737 MAX-specific simulator sessions as well as computer-based or in-class training for all pilots.
Modifying aircraft and getting pilots trained will likely take several weeks for operators. CAAC’s Dec. 2 directive does not discuss possible service-return timing or deadlines for lifting its operations ban.
China was the first regulator to ban the 737 MAX following the March 2019 Ethiopian Airlines Flight 302 accident that led to the 385-aircraft fleet facing a worldwide grounding. CAAC stuck with three basic conditions for the type’s return to service: updated designs must pass airworthiness inspection; pilots must receive adequate training for them; and the causes of the two fatal accidents must be clear and adequately addressed through modifications. Boeing deployed a 737 Max 7 from Seattle to Shanghai in August for a week-long demonstration to Chinese regulators as part of the return-to-service process. Release of the pilot-training requirements will remove the last regulatory hurdle in China, leaving airlines to carry out with the modifications and pilot preparation allow the aircraft return to service in the world’s second-largest aviation market.
“The CAAC’s decision is an important milestone toward safely returning the 737 MAX to service in China,” Boeing said in a statement. “Boeing continues to work with regulators and our customers to return the airplane to service worldwide.”
China’s approval for airlines to operate and begin taking delivery of additional 737 MAXs is a major factor in Boeing’s plan to increase 737 MAX monthly production to 31/month in early 2022. Aviation Week Intelligence Network Fleet and Data Services shows 444 737 MAX family aircraft on order to Chinese airlines and lessors in addition to 97 grounded under the current ban.
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