Emergency AD Issued On B737 Max

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The FAA has issued an Emergency Airworthiness Directive (PDF) that directs the owners of all Boeing 737 Max aircraft to amend their operating manuals, to avoid a control problem like the one that apparently caused the fatal crash of a Max 8 last week. “Possible erroneous angle-of-attack inputs on Boeing 737 Max aircraft … can potentially make the horizontal stabilizers repeatedly pitch the nose of the airplane downward, making the aircraft difficult to control," the FAA says in an emergency AD dated Nov. 7. The airplanes are not grounded, and the owners have three days to comply with the AD, which requires a revision to the airplane flight manual.

“This emergency AD was prompted by analysis performed by the manufacturer showing that if an erroneously high single angle of attack (AOA) sensor input is received by the flight control system, there is a potential for repeated nose-down trim commands of the horizontal stabilizer,” the AD reads. “This condition, if not addressed, could cause the flight crew to have difficulty controlling the airplane, and lead to excessive nose-down attitude, significant altitude loss, and possible impact with terrain.” The AD requires revising certificate limitations and operating procedures to provide the flight crew with runaway horizontal stabilizer trim procedures to follow under certain conditions.

Comments (3)

Boeing should be grounding the entire 737 Max fleet pending hardware/software fixes, rather than edits to its manual set. The implication is that the Lion Air pilots were at fault for not disabling the pitch trim. Instead of wrestling with the control column, they should have pulled out the checklist! My condolences to the passengers and crew of JT610.

Posted by: Clifford Walinsky | November 9, 2018 12:10 PM    Report this comment

Reminds me of some air carrier crash years ago where the FAA's solution was to placard the rudder against full deflection instead of fixing the problem.

That's not "promoting safety."

Posted by: Mike P | November 10, 2018 1:47 AM    Report this comment

Methinks the FAA gets a kick out of playing Russian Roulette by hoping that no other 737 plows in during their ill-advised "grace period." And, who needs an "automatic pushover" anyway? Isn't the stick shaker considered to be sufficient news that a stall is about to occur? Gimmie a break!

Posted by: Carl Jordan | November 10, 2018 8:24 AM    Report this comment

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