An American Airlines 737 Max declared an emergency after a mechanical issue and landed safely

• A Boeing 737 Max declared an emergency before landing safely on Friday.
• The 737 Max model has been plagued with issues since it was grounded in 2019.
• American was the first US airline to resume 737 Max flights when the plane returned to service.

A Boeing 737 Max bound for New Jersey's Newark Liberty International Airport declared an emergency after the captain shut down one engine over a possible mechanical issue, American Airlines said Friday.

American's Flight 2555 from Miami landed safely at Newark without incident, the airline said. The airline said the issue was related to an engine oil-pressure or -volume indicator and not the result of anything related to the Maneuvering Characteristics Augmentation System linked to the two fatal 737 Max crashes that prompted the plane's 20-month grounding.

"American Airlines flight 2555, with service from Miami (MIA) to Newark (EWR), experienced a possible mechanical issue as it approached its final destination," American Airlines said in a statement to Insider. "The aircraft landed safely and without incident at 3:28 p.m. ET, and taxied to the gate under its own power. All customers deplaned normally, with no reported injuries to passengers or crew."

Boeing Co. said it was aware of the American flight, and the Federal Aviation Administration said it would investigate.

American was the first US airline, followed closely by United, to return the 737 Max to service in December. Service was halted in March 2019. American was also the first airline to commit to buying the new 737 Max in 2011. Boeing's plane had problems from the start. Because engine placement caused the plane to pitch up, Boeing installed an autopilot system to angle the planes down.

The sensors failed, causing two planes to crash months apart with a total 346 passengers. The US was one of the last countries to ground the 737 Max.

After over a year of work and testing, the Federal Aviation Administration allowed test flights to resume. It was officially ungrounded in November after required fixes. Now other US airlines are planning to incorporate the 737 Max into their fleets. United Airlines just placed an order for 25 more of the model, while Alaska Airlines just began flights with the 737 Max, Insider's Tom Pallini reported.