DOT to Review FAA’s Response to 737 Max Smoke Concerns

DOT to Review FAA’s Handling of Boeing 737 Max Smoke Issue

The U.S. Department of Transportation’s (DOT) top inspector has initiated a review of the Federal Aviation Administration’s (FAA) response to a critical engine problem affecting Boeing 737 Max aircraft. This issue involves the rapid accumulation of thick smoke in cockpits and cabins, raising significant safety concerns. The investigation follows two high-profile smoke incidents in 2024 and subsequent measures including temporary production limits and groundings of certain 737 Max jets.

The Load Reduction Device and Its Risks

Central to the problem is the Load Reduction Device (LRD) installed in the 737 Max’s CFM International Leap-1B engines. The LRD is intended as a safety feature to prevent catastrophic engine damage in the event of a fan blade failure. However, when triggered, it can inadvertently cause oil to leak into hot engine components, producing dense smoke that is then circulated into the cockpit or cabin through the aircraft’s bleed air system.

A memorandum dated 16 April from Nelda Smith, assistant inspector general for aviation audits at the DOT’s Office of Inspector General, outlined the scope of the review. The audit aims to evaluate the FAA’s actions following recent incidents involving toxic smoke and fumes entering aircraft cockpits and cabins due to LRD activation. Particular attention will be paid to the FAA’s decision-making process regarding the LRD issue.

The FAA has faced criticism for its November 2024 decision not to take immediate corrective action despite recommendations from its own accident investigation panel. In response to the DOT’s review, the FAA stated, “We welcome outside scrutiny and will fully cooperate with the audit.” Boeing and CFM International, a joint venture between GE Aerospace and Safran Aircraft Engines, have not yet issued comments.

Incidents and Industry Response

The urgency of the issue intensified after two inflight events involving Southwest Airlines 737 Max 8 aircraft. On 5 March 2023, a right engine collided with a turkey vulture shortly after takeoff from Havana, activating the LRD and filling the cabin with “thick acrid smoke,” according to an FAA report. Later, on 20 December 2023, the left engine of another Southwest 737 Max 8 ingested a bald eagle, triggering the LRD and releasing a “toxic amount of smoke and fumes” into the cockpit. In both cases, pilots managed to land safely, but the incidents highlighted the potential severity of the problem.

FAA documents reveal that smoke from a left-side LRD activation can reduce cockpit visibility to as little as five inches within 30 seconds. The 737 Max’s unique engine configuration means the left engine supplies air to the cockpit, while the right engine supplies the cabin. Consequently, an LRD failure on either side can rapidly degrade air quality for crew or passengers.

In response, Boeing is developing a software update aimed at mitigating the risk. Meanwhile, at least one airline has cautioned pilots that similar issues could arise in Airbus A320neo-family aircraft powered by CFM Leap-1A engines. CFM International has stressed the rarity of such events and the overall reliability of its Leap engines but acknowledged the need to improve the LRD’s operation specifically for the 737 Max.

As the DOT audit continues, the FAA’s management of the issue remains under intense scrutiny. Regulators, manufacturers, and airlines are collaborating to enhance safety measures and restore confidence in the 737 Max fleet.