The US regulator, as part of an internal review, has preliminarily concluded that FAA officials largely deferred to Boeing's assessments of the accident-ridden 737 MAX during the certification process, the person said.
Boeing's top-selling 737 MAX narrow-body planes have been grounded globally since mid-March following two plane crashes that killed 346 people. A common link in both crashes was the Maneuvering Characteristics Augmentation System.
During the FAA certification, Boeing did not flag to regulators that a failure of the MCAS could lead to a catastrophic event, a classification that would have triggered more regulatory scrutiny, The Wall Street Journal reported Tuesday.
The FAA approved the 737 MAX in early 2017 and the plane entered into service in May of that year.
In both the Lion Air crash in Indonesia in October and the Ethiopian Airlines crash in March, the MCAS pointed the plane sharply downward based on a faulty sensor reading, hindering pilot control after takeoff, according to preliminary crash investigations.
The FAA's internal review did not conclude that Boeing intentionally misled the agency, the source told AFP.
Rather, the agency concluded that further review was not needed of the MCAS because the FAA itself concluded the system did not affect the trajectory of the plane.
"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. At lower speeds, greater control movements are often necessary," an FAA spokesman said.
Boeing did not immediately respond to AFP requests for comments.
Acting FAA head Daniel Elwell is expected to face tough questioning on Boeing at a congressional hearing on Wednesday. At a prior hearing, lawmakers criticized the agency for being too cozy with Boeing and questioned why the agency was the last major regulator to ground the 737 MAX after other bodies took action.
American Airlines and Southwest Airlines, two US carriers that fly the 737 MAX, were subpoenaed by the US DOJ in November, said two people familiar with the matter.