The U.S. Federal Aviation Administration (FAA) has issued a Safety Alert for Operators (SAFO) to airlines operating Boeing 737 Next Generation (NG) and 737 MAX aircraft regarding a potential risk of rudder control jamming. The issue stems from faulty Collins Aerospace SVO-730 Rudder Rollout Guidance Actuators (RRGA), which could restrict rudder movement during critical flight phases, including landing rollout.
The alert follows an incident involving a Boeing 737 MAX 8 in which the rudder pedals became unresponsive during landing at Newark Liberty International Airport in February 2024. Initial investigations by the FAA suggest that moisture accumulation within the actuator likely froze during the flight, leading to the restricted rudder movement. This malfunction raises concerns for Category IIIB landings, where precise rudder control is critical due to low-visibility conditions.
According to the FAA, this issue affects Boeing 737-600, -700, -800, -900, 900ER (737NG), as well as 737 MAX 8, -8200, and 9 aircraft equipped with the Collins Aerospace SVO-730 RRGA. Even though some actuators are mechanically connected but electrically deactivated, the risk remains if moisture enters and freezes within the actuator, potentially jamming the rudder.
This warning aligns with a recent report from the National Transportation Safety Board (NTSB), which highlighted a manufacturing flaw affecting over 353 actuators delivered since 2017. The NTSB’s findings showed that a sealed bearing assembly flaw makes the actuator vulnerable to moisture ingress. Tests confirmed that moisture freezing inside the actuator can lead to rudder restrictions or jamming, particularly during landing rollout.
NTSB urged immediate action
The NTSB has issued urgent safety recommendations to Boeing and the FAA, calling for a revision of current flight manual procedures. The current guidance advises pilots to apply maximum force to overcome a rudder jam. However, the NTSB warns that this could cause undesired rudder deflection, increasing the risk of runway excursions or loss of control during landing. The board has also urged the FAA to determine whether affected actuators should be removed from service and replaced with compliant units.
In its report, the NTSB also encouraged the FAA to notify international aviation regulators, stressing the global impact of this issue. Operators worldwide are advised to take precautionary measures to mitigate potential risks.
FAA recommendations for crews
In the meantime, the FAA has issued immediate recommendations for flight crews. If rudder restrictions are encountered in flight, Boeing advises pilots to follow the Jammed or Restricted Flight Controls Non-Normal Checklist (NNC). For incidents occurring on the ground, pilots are instructed to use differential braking to maintain control, avoiding the use of nosewheel steering above 100 knots unless necessary.
The autopilot system on affected aircraft is designed to conduct rudder servo tests during dual autopilot ILS approaches, helping crews identify potential rudder issues early. A NO LAND 3 message will alert flight crews of any anomalies, and crews are urged to select dual autopilot approaches when possible to ensure the system is functioning correctly.
Boeing has yet to announce a timeline for replacing the faulty actuators or revising the flight manual procedures. However, both the FAA and NTSB have classified the situation as urgent, with the potential to affect over 350 aircraft currently in service.
As the investigation continues, both Boeing and the FAA are expected to release further updates. In the meantime, airlines operating Boeing 737NG and 737 MAX aircraft are urged to remain vigilant and follow the safety protocols outlined by the FAA and NTSB to mitigate the risk of rudder control issues during flight.
