The National Transportation Safety Board (NTSB) issued an urgent safety recommendation for the CFM International LEAP-1B engines, which exclusively powers the 737 MAX jets. The safety board raised concerns over smoke entering either the cockpit or cabin as a result of damage to the engines.
“The NTSB found that the engine load reduction device, or LRD, a safety feature designed to reduce the severity of vibrations transmitted from a damaged engine to the airframe, can result in damage to the engine oil system,” read the NTSB in a statement. “Such a condition can allow smoke from hot oil to enter the ventilation system and ultimately the cockpit or passenger cabin.”
The recommendations follow NTSB launching an investigation into two separate incidents in March and December 2023, both on Southwest flights.
The March incident saw white vapour fog fill the passenger cabin after birds were ingested into an engine shortly after takeoff from Havana, Cuba. The aircraft shortly returned to the airport. Similarly, the Southwest flight departing New Orleans in December 2023 saw its 737 flight deck fill with white smoke. Crew reported that the smoke was so thick that the captain had “difficulty seeing the instrument panel”.
“The NTSB issued an urgent safety recommendation to the Federal Aviation Administration (FAA) asking the agency to ensure that operators inform flight crews of airplanes equipped with the affected engines,” the safety board said.
Boeing has since revised flight manuals for pilots to include measures to prevent smoke entering either the cockpit or cabin in such an event. The board also requested the FAA and the European Union Aviation Safety Agency (EASA) to require all operators of the affected engines implement software modifications developed by CFM and Boeing.
The safety board issued additional safety recommendations to evaluate the potential for similar issues on the LEAP-1A and LEAP-1C engines. The former powers the A320neo family jets, while the latter is used exclusively for the COMAC C919 aircraft fleet.