DOT inspector raises concern about FAA’s response to Leap engine smoke incidents

GE and Boeing are working to address the problem with a software update that the FAA intends to mandate.

The US Department of Transportation’s (DOT) top inspector has raised concern about the Federal Aviation Administration’s response to an engine-related issue that can cause Boeing 737 Max cabins or cockpits to fill with smoke.

A newly released report from the DOT’s Office of Inspector General says the FAA indeed followed its own processes in responding to the issue, which involves CFM International Leap turbofans.

But it says the FAA should do more and cites the length of time it will take to update 737 Max with new engine software to address the problem.

“We identified several issues that could require further analysis and additional action,” says the report, which includes several recommendations.

The FAA says it intends to adopt those recommendations. It also defends its actions, saying it has taken “a comprehensive approach” to addressing the issue.

“Work to address these recommendations is underway,” adds GE.

Boeing does not immediately comment.

FUMES AFTER BIRD STRIKES

The DOT launched its review last year amid controversy over how the FAA responded to an issue that caused two in-flight incidents involving Southwest Airlines 737 Max jets.

Both aircraft suffered bird strikes to one Leap-1B, damaging the engines’ fans and prompting activation of “load reduction devices”. Those devices, a safety feature, separate damaged fans from surrounding structures to prevent broader aircraft damage.

But LRD activations can cause engine oil to spill onto hot engine sections, creating smoke that can be pumped into the cabin or cockpit, depending on which engine is affected. That is what happened on the two Southwest flights.

EASA has warned of similar events affecting Leap-1As, which power Airbus A320neo-family jets.

CFM is working with Boeing to address the problem by developing a software update that closes a Leap-1B valve after LRD activation, minimising fumes.

The DOT report notes Boeing and the FAA agreed to a 3.6 year “compliance” schedule for having the software fully integrated into the fleet.

The FAA is expected to approve the software at an aircraft level in the third quarter of 2026, after which Boeing is expected to issue a service bulletin calling on operators to install it. Then, the FAA would publish a proposed rule requiring the install, with a likely six-month compliance timeline.

The DOT estimates the update will not be installed across the fleet until mid-2028.

“Any unforeseen adverse LRD events or delays in developing or implementing LRD activation solutions could introduce additional risk to the flying public,” the report says.

FAA REVIEW PROCESS

The FAA’s Office of Accident Investigation and Prevention (AVP) investigated the two 2023 incidents and made several recommendations to the FAA’s Corrective Action Review Board” (CARB) — the panel that determines regulatory responses.

The CARB agreed with the AVP that the FAA should require the software update. 

But it disagreed with other recommendations. Those include that the FAA “review all novel and unique” 737 Max features, that 737 Max carry different pilot oxygen masks and that Boeing be required to revaluate its assessment of LRD activation likelihood.

The DOT report says investigators expressed concern about the CARB’s methods and notes that even CARB members could not agree on methods of calculating the probability of LRD activations.

The DOT report recommends the FAA take additional steps. It says the agency should notify Leap-1B operators if the software update takes longer than planned, work to ensure new pilots understand the LRD risk, and help airlines adopt new pilot training to address limited cockpit visibility.

The FAA says it will implement those recommendations.