NTSB probing ‘stuck’ control incident on Boeing 737 Max

By Pete Muntean and Gregory Wallace, CNN

(CNN) — Boeing is now party to a new federal investigation involving a 737 Max after United Airlines pilots reported that part of the flight controls became jammed as they landed in Newark last month.

In a newly-released preliminary report of the February 6 incident, the National Transportation Safety board says the pilots of the Boeing 737 Max 8 “experienced ‘stuck’ rudder pedals during the landing rollout.” The rudder controls an airplane’s yaw, or the left and right swinging of the nose.

The NTSB says none of the 161 people on United flight 1539 were injured and the plane returned to the gate, though United maintenance crews were able to “duplicate the reported rudder system malfunction” during a test flight three days later.

The investigation is the latest to involve a nearly-new Boeing 737 Max aircraft following the door plug blowout on an Alaska Airlines 737 Max 9 on January 5. The NTSB says in this latest incident, the 737 Max 8 was delivered from Boeing to United Airlines in February 2023.

The NTSB says the servo in question was disabled by United Airlines, but cold temperature tests by the company that makes an autopilot servo that is connected to the 737 Max 8 rudder controls, Collins Aerospace, as part of the investigation revealed the servo’s “output crank arm would prevent the rudder pedals from moving.”

“We’re grateful to our pilots and maintenance teams for their professionalism in diagnosing this issue. We’ll continue to work with Boeing, the NTSB and the FAA on next steps for these aircraft,” United said in a statement.

This is the first instance of this issue being reported on a 737 Max, according to a source familiar with the matter, but not the first instance on any Boeing plane.

A similar occurrence was reported twice, both in 2019, on the previous model of 737. That aircraft – the 737 Next Generation – uses a rudder pedal system. In both previous cases, the issue was fixed by replacing parts on the plane, the source said.

“We worked closely with United Airlines to diagnose the rudder response issue,” Boeing said in a statement. “With coordination with United, the issue was successfully resolved with the replacement of three parts and the airplane returned to service last month.”

United said the faulty parts are not part of the typical configuration used on its aircraft. The plane was originally built for another airline but went to United instead.

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