Boeing 737 planes with a specific rudder part not to be used for low-visibility landings: DGCA

Airlines have also been told to carry out a safety risk assessment; DGCA advisory follows US transport investigation body pulled up the FAA after a probe into a February incident involving a 737 MAX plane

Aviation safety regulator DGCA has asked operators of Boeing 737 aircraft with a specific rudder part to not use the planes for low-visibility landings due to a “possible risk of jamming” after a loss of control incident involving a United Airlines flight in New Jersey in February.

The advisory, which comes ahead of the upcoming fog season, is effective for both Boeing 737 NG aircraft as well as the new MAXs, said a senior Directorate General of Civil Aviation (DGCA) official.

Three Indian airlines have the 737 aircraft in their fleet, i.e. Air India Express (61), Akasa (25) and SpiceJet (11 in service). Air India Express said five of their 88-aircraft strong fleet had the specific rudder part, while SpiceJet said there were no planes in its fleet with the snag-prone component. Akasa did not reply to a query mailed to it. The DGCA’s advisory is specifically for the Collins Aerospace SVO-730 rudder actuator.

“All Category IIIB approach, landing, and rollout operations (including practice or actual autoland) must be discontinued for airplanes until further notice,” the DGCA has advised airlines.

CAT IIIB approach is a precision aid used in low-visibility conditions and includes two radio beams which together provide pilots with both vertical and horizontal guidance during a landing. It can be used when the runway visibility range is less than 175 metres but not less than 50 metres.

Additionally, the DGCA has asked airlines to carry out a safety risk assessment, inform crew about the possibility of a jammed rudder actuator as well as include discussion about the potential rudder control system and involve practice sessions involving mitigation measures during trainings.

“We have initiated the process of compliance in adherence to the regulatory requirements,” an Air India Express spokesperson said.

The rudder rollout guidance actuator, which is installed in the tail of some B-737NG and 737MAX airplanes, is designed to control the rudder’s movement during Category IIIB approach, landing and taxiing operations. Although it is not used in non-precision landings, the actuator remains mechanically engaged with the rudder system.

The DGCA caution follows a strongly worded letter from the US accident investigation body, the National Transport Safety Board (NTSB), to its aviation safety regulator Federal Aviation Authority last week accusing the latter of not taking the issue of a rudder actuator malfunction seriously even six months since the former’s preliminary report into a loss of control incident in February involving a Boeing 737 MAX aircraft of United Airlines when pilots complained of a problem with the rudder part while landing at the Newark Liberty International Airport, Newark, New Jersey.

On September 26, the NTSB also issued an urgent safety recommendation on the Boeing 737 rudder system to Boeing and FAA potential for a jammed or restricted rudder control system on some 737 airplanes. It said its investigators tested the rudder control components from the incident airplane and another aircraft and found that when tested in a cold environment, the actuators’ function was “significantly compromised.” The NTSB further said that Collins Aerospace subsequently determined that a sealed bearing was incorrectly assembled during production of the actuators, leaving the unsealed side more susceptible to moisture that can freeze and limit rudder system movement.

Collins notified Boeing that more than 353 actuators it had delivered to Boeing since February 2017 were affected by this condition. Out of this, 271 could be installed on aircraft in service by airlines outside the U.S., the NTSB warned FAA. It also slammed Boeing for failing to inform airlines about the failed component.

The NTSB also recommended that if the FAA determines the affected actuators should be removed, it should direct U.S. operators to do so as well as notify aviation regulators in other countries to require their removal until replacements were available.

In response to concerns raised by the NTSB, Boeing has proactively informed affected airlines about the snag-prone part, which it said did not impact safety of flight. “In August, we informed affected 737 operators of a potential condition with the rudder rollout guidance actuator,” Boeing said in a statement issued last week, adding that the specific component is part of an optional autoland system which included layers of redundancy.

Published - October 07, 2024 05:27 pm IST