Indonesian investigators said yesterday that a sensor measuring the angle of the plane had malfunctioned despite having recently been replaced.
That sensor is meant to maintain air flow over a plane's wings but if it malfunctions it can cause the plane's computers to erroneously think it is in a aerodynamic stall - which can then cause aircraft to abruptly dive. The FAA said "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".
Virgin Australia has ordered 40 new 737 MAX 8 models for its fleet - to be in use by next year - but will not back out of the purchase in light of the guidelines.
Lion Air JT610 plunged into the Java Sea less than half an hour after taking off from Jakarta on a routine flight to Pangkal Pinang city.
Boeing said its bulletin underscored "existing flight crew procedures" created to address circumstances where the information coming into the cockpit from the sensors was wrong.
The FAA said the order is effective immediately and covers 45 aircraft in the United States operated by carriers including Southwest Air Co, United Airlines and American Airlines Group Inc and addresses erroneous angle of attack inputs.More news: Judge refuses to limit Arizona vote count, sets hearing
On Tuesday, Indonesian investigators found that the Lion Air flight had a malfunctioning air speed indicator for its last four flights and crucially, at the time of the crash.
The bulletin is being prepared based on preliminary findings from the crash of one of the planes off the coast of Indonesia, said the person, who asked not to be named discussing the inquiry.
The pilot of the flight requested a return to Denpasar but the situation corrected itself and he elected to continue to Jakarta.
Boeing will caution its customers of "erroneous readings" from a flight-monitoring system can cause the planes to abruptly dive, Bloomberg quoted an anonymous source as saying. The head of Indonesia's National Transportation Safety Committee, Soerjanto Tjahjono, told reporters in Jakarta on Monday that he was discussing the options for wider inspections with Boeing and his us counterparts.
Aviation systems must account for possibility of misinterpretations of situations and foggy memories of procedures outlined in the manuals that come with these huge, complicated, and incredibly sensitive vehicles.
Authorities were still searching for the cockpit voice recorder, the second so-called "black box".