The chair of the National Transportation Safety Board (NTSB) slammed the Federal Aviation Administration (FAA) on Monday for downplaying the urgency about a Boeing 737 safety issue NTSB previously raised.

In a letter addressed to FAA Administrator Michael Whitaker, NTSB Chair Jennifer Homendy said the agency failed to take action after the pilots of a United Airlines Boeing 737 MAX reported that the rudder pedals got stuck when landing at Newark Liberty International Airport in New Jersey on Feb. 6.

The NTSB issued an "urgent" safety alert on Thursday, warning that some 737s were outfitted with certain rudder actuators that could cause the aircraft to careen off the runway when landing. These faulty parts may be in use in by at least 40 foreign carriers, according to Homendy.

There may be 271 defective components in use by overseas airlines, as well as 16 in the United States, Homendy said, citing information provided by Boeing in August. Dozens more have yet to be installed.

It's the latest embarrassment for Boeing's beleaguered 737 MAX line after a door-sized panel blew off a 737 MAX in January and two 737 MAX crashes in 2018 and 2019 that killed a total of 346 people.

"Although our investigation is ongoing, I am disappointed that it does not appear that the FAA has initiated urgent actions to address the risk of jammed rudder controls in the 6 months since our preliminary report on this incident was issued," Homendy wrote in the letter, which was obtained by Newsmax.

"The case for urgent action is even greater since, after we opened our investigation, the FAA became aware of two similar incidents that had occurred with foreign operators in 2019," she said.

United Airlines said on Monday that it removed the rudder actuators in question from its 737s, CNN reported. In her letter, Homendy said the NTSB is "concerned of the possibility that other airlines are unaware of the presence of these actuators on their 737 airplanes."

Bloomberg reported that the FAA said last week that United is the only U.S. airline that had the affected parts. The NTSB did not specify which other American carriers might be using the parts.

The FAA said in a statement obtained by CNN that it has assembled a team to address the issue and is notifying airlines internationally. The regulator is also planning to conduct additional simulator testing in October.

"We thank the NTSB for the recommendations, and we are taking them seriously," the FAA said Monday.

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