As investigators continue to probe the certification process for the Boeing 737 MAX in the wake of the fatal crashes of Ethiopian Airlines Flight 302 and Lion Air Flight 610, it is again being suggested that modifications made to the MAX’s Maneuvering Characteristic Augmentation System (MCAS) after it was initially reviewed by the FAA were not thoroughly vetted by the agency. As previously reported by AVweb, the changes in question increased how much the system could move the stabilizer—from roughly 0.6 degrees in a 10-second cycle to 2.5 degrees in a similar timeframe—and allowed it to activate in a wider array of circumstances. Citing an unnamed source, TheNew York Timesreported that the changes were made after flight testing found that the MAX handled “less predictably” than desired “just before a stall at various speeds.”
“The change to MCAS didn’t trigger an additional safety assessment because it did not affect the most critical phase of flight, considered to be higher cruise speeds,” an FAA spokesman told theTimes. “At lower speeds, greater control movements are often necessary.” The preliminary accident report on Flight 302 released last Thursday confirmed that the aircraft’s MCAS commanded almost maximum nose-down trim in response to a malfunctioning angle-of-attack sensor. Although final reports have not been released for either accident, similar MCAS behavior was noted in the Lion Air crash.
Along with an audit by the Department of Transportation’s Inspector General, separate MAX investigations are reportedly being conducted by the FBI, House Transportation Committee and Senate Committee on Commerce, Science and Transportation. On the list of issues under scrutiny is whether the Organization Designation Authorization (ODA) program, which allows the chronically understaffed FAA to designate authority for activities like design change approvals to outside organizations including the aircraft manufacturers themselves, can create a conflict of interest for safety inspectors.
Boeing is also facing an increasing number of legal challenges related to the 737 MAX. In addition to lawsuits filed on behalf of families of victims killed in both MAX crashes, a Boeing shareholder filed a class action suit (PDF) on Tuesday alleging that the company misled investors about the safety of the MAX and concealed safety issues associated with the aircraft’s handling characteristics. Also this week, China Eastern Airlines, which operates 14 737 MAXs, asked Boeing to provide compensation for service disruptions caused by the grounding of the aircraft after the crash.