Boeing 737 hit with new warning that the rudder pedals can get stuck, posing safety risk

The rudder pedals on Boeing 737 jets can get jammed in the neutral position due to collected moisture freezing over in a rudder part, the National Transportation Safety Board said in a new report.

The issue was discovered when pilots on United Airlines flight 1539 from Nassau, Bahamas, to Newark, New Jersey, could not get the plane’s rudder pedals to move out of neutral during touchdown on Feb. 6.

The pilot was able to use the Boeing 737’s nose wheel tiller to keep the plane straight and was able to move the rudder using the pedals shortly after the plane landed on the runway, the NTSB said. No one on board was injured.

A preliminary investigation found that moisture gathered in an incorrectly sealed part made by Collins Aerospace. The moisture froze over and thereby jammed the rudder and its pedals.

While about 87 pounds of force was capable of clearing the jam in the rudder in post-incident testing, using that amount of force while landing could “also result in a large input to the rudder pedals and a sudden, large, and undesired rudder deflection that could unintentionally cause loss of control or departure from a runway,” the NTSB said.

In addition to landings, the NTSB also reported concern about the effects a jammed rudder could have during certain flight situations, mainly when a plane’s engine goes out or when it is dealing with high crosswinds.

If the rudder was jammed during one of those scenarios, “the amount of rudder available to respond to these conditions might be insufficient to maintain control of the airplane if the jam is not cleared. Furthermore, the force required to clear the jam may result in a large, sudden, and undesired input to the rudder. Without the appropriate pilot response, a loss of airplane control could result,” the NTSB said in its report Thursday.

In August, Collins Aerospace let Boeing know that 353 of the incorrectly sealed parts had been delivered since 2017, the NTSB said. Of those parts, nine had been installed on United Airlines planes and were removed earlier this year following the Feb. 6 incident.

Only 25 U.S.-registered planes had the improperly sealed rudder parts, Boeing told the NTSB on Aug. 28, and the 16 non-United planes were leased to non-U.S. operators.

NTSB urged Boeing to notify 737 crews about the possibility of jams and to come up with a solution better than applying more force to the pedals. The agency urged the Federal Aviation Administration to determine whether the improperly sealed parts should be removed and, if so, notify international regulators about the issue and recommend that they also remove the parts.

The FAA said Thursday that a corrective action review board would be convened Friday to figure out what to do about the NTSB recommendations, according to both the Seattle Times and Reuters.

Boeing told both outlets that flight crews will “have the appropriate operating procedures.”

Collins Aerospace parent company RTX Corporation, formerly known as Raytheon Technologies, told Reuters that it will “work closely with the NTSB and Boeing on this investigation. We are supporting Boeing and operators to mitigate operational impacts.”