U.S. aviation regulators are examining whether pilots of Boeing's 737 Max planes should take new precautions, following two incidents in which planes were filled with smoke after large birds struck the engines. 

A small group of investigators at the Federal Aviation Administration (FAA) has developed internal recommendations on how to address the issue, including potentially requiring pilots to shut down one or both air conditioning packs during takeoff that regulate airflow in the cockpit. 

The change would be temporary until Boeing implements a permanent fix, according to the recommendations, seen by Bloomberg News. They also urged the FAA to review all novel and unique features of the 737 Max to ensure that they are adequately communicated in pilot operating manuals. The agency has not made a final decision about the matter. 

A representative for the FAA said on November 21 that the agency is convening a Corrective Action Review Board “in the coming weeks,” and that the board’s work will include “thoroughly evaluating the internal FAA safety recommendations.” 

Separately, the National Transportation Safety Board said in a November 22 statement that it would conduct its own investigation into the December 2023 bird-strike incident, the most recent of the two.

The mishaps involved a Boeing 737 Max aircraft flown by Southwest Airlines, which was equipped with LEAP-1B engines made by CFM International, a joint-venture of GE Aerospace and Safran SA. The FAA said it’s collaborating with Boeing, CFM and European aviation safety regulators to address the engine issue. 

The review board — which identifies and evaluates safety issues, develops corrective steps and can order changes at airlines or manufacturers — will “examine the data and develop a path forward,” the FAA said in a statement. “The FAA has determined this is not an immediate flight-safety issue.”

Following the incidents, Southwest said it notified pilots about the effects of the bird strikes and reiterated safety procedures for such incidents. The airline “continues to address this issue through its robust safety management system while working with the manufacturers and safety regulators to identify a permanent solution,” it said in a statement on November 21. 

The system linked to the smoke incidents doesn’t appear in pilot training or operating materials, which “is very concerning,” the internal FAA group said, likening it to the flight control system tied to two fatal 737 Max crashes in 2018 and 2019. 

Bird Strikes

The smoke incidents involved a Southwest flight from Havana to Fort Lauderdale, Florida, on March 5, 2023, in which at least one turkey vulture was sucked into the engine. In the second, a female bald eagle hit the engine of a New Orleans to Tampa flight on December 20. Both incidents caused heavy fan blade damage, according to a CFM presentation seen by Bloomberg News. 

In both instances, damage to the fan blades activated a load reduction device in the LEAP-1B engines designed to reduce unbalanced dynamic loads in engine structures, followed by shutdowns. Engine oil sumps were also damaged in both cases, allowing oil to hit the high-temperature engine compressor, resulting in smoke and fumes that can be fed into the cockpit from the left engine and into the cabin from the right, according to a memo sent by Southwest to its pilots in February.

“These engine failures occurred during a critical phase of flight and were further compounded by the immediate presence of smoke and fumes associated with the severe engine damage entering either the flight deck or the cabin through the air conditioning system,” the bulletin said. The note, along with a similar one from American Airlines Group Inc. to its pilots, also contained information from Boeing. 

“Load Reduction Devices have been widely used across the industry for more than 20 years and operated as designed,” a spokesperson for CFM said in a statement. “We are collaborating with the FAA, EASA and Boeing to determine if there are any learnings from recent events.” 

A spokesperson for Boeing said the planemaker is working with the authorities that are investigating the incidents. “We continue to follow regulatory processes to properly address potential issues and ensure the continued safety of the global fleet,” they said.