Southwest 737 diverted from Austin after metal debris found in right engine

Quick summary

Southwest Airlines flight WN-375 diverted back to Austin–Bergstrom International Airport on June 4, 2026, after pilots reported right-engine problems climbing through 13,000 feet en route to Phoenix. Post-landing inspection found what the FAA has formally described as “metal debris and damage to the right engine.” The 21-year-old Boeing 737NG has not flown since. The FAA has opened an investigation.

The source of the metal debris remains unidentified. This is the same engine family — the CFM56-7B — involved in the 2018 Southwest Flight 1380 accident that killed one passenger.

A Southwest Airlines Boeing 737NG bound for Phoenix turned back to Austin on June 4 after pilots reported a right-engine problem at 13,000 feet — low enough that the aircraft had barely cleared its climb phase. The plane landed safely roughly 40 minutes after departure, was held on the runway while airport fire services inspected the aircraft, and was then cleared to taxi to the terminal under its own power. Passengers deplaned normally. Nobody was hurt.

What came next is the part that matters. A detailed post-landing inspection revealed what the FAA has officially documented as “metal debris and damage to the right engine.” The aircraft has not returned to service.

The pilots told air traffic control they had not received an engine fire warning — but whatever the cockpit instruments were showing was serious enough to declare a diversion and request emergency services on standby at the runway. That gap between “no fire warning” and “metal debris confirmed inside the engine” is exactly what investigators will be working to close.

The aircraft involved is a 21-year-old 737NG powered by CFM56-7B engines. That engine type is the same one that fractured catastrophically on Southwest Flight 1380 in April 2018, sending a fan blade through the engine cowling, depressurizing the cabin, and killing one passenger. The 2018 accident led to intensified fan-blade inspection requirements — requirements that, for certain cowling design changes, airlines are not required to complete until 2028.

What the FAA found — and what it still doesn’t know

Flight WN-375 departed Austin–Bergstrom at approximately 11:53 am on June 4. Weather in the Austin area delayed the return approach, forcing the aircraft to descend to around 5,000 feet and circle north of the airport before being cleared to land. That detail matters: the crew managed a non-emergency return in degraded conditions without declaring a full emergency, which speaks to the controlled nature of the situation — but also means the engine was running in some state for longer than a straight-in approach would have required.

The FAA’s finding of “metal debris and damage” inside the right engine is the operative phrase here. Metal debris inside a jet engine means something broke. The question — not yet answered — is what broke, whether it was contained within the engine, and whether the failure mode has any connection to the fan-blade fatigue issues that defined the 2018 Flight 1380 investigation.

This is not the first time Southwest has faced post-departure engine scrutiny in recent years. In April 2024, a Southwest 737-800 operating Flight 3695 from Denver to Houston returned to Denver after an engine cowling separated during takeoff and struck a wing flap. The NTSB later linked that event to maintenance work performed the night before — no injuries, no fleet-wide directive, disruption confined to that aircraft’s rotations. The Austin event is structurally similar in scope so far, but the debris finding adds a layer of uncertainty that the Denver cowling loss did not carry.

Why the debris finding changes the calculus

Engine diversions happen. What regulators and investigators look for is the failure mode — specifically, whether the damage pattern matches a known fatigue or maintenance issue that could exist across other engines in the same fleet. The CFM56-7B has a documented history with fan-blade fatigue cracking, which is why the FAA issued enhanced ultrasonic inspection requirements after 2018. If the Austin debris analysis points to a similar fatigue mechanism, the regulatory response would not be limited to this one aircraft.

That’s the scenario that could ripple outward. A targeted airworthiness directive requiring accelerated inspections across Southwest’s CFM56-7B-powered 737NGs would temporarily pull aircraft from rotation until checks are completed — tightening capacity on short-haul routes like AUS–PHX where Southwest operates with high aircraft utilization and limited slack. The Denver cowling event in 2024 did not trigger that response. Whether Austin does depends entirely on what the debris analysis reveals.

For now, the disruption is local: one grounded aircraft, one affected rotation, Southwest substituting equipment or consolidating departures from Austin. That can change quickly if the FAA’s findings point somewhere broader.

Steps to take if you’re flying Southwest from Austin

The aircraft is grounded and the FAA investigation is active — Southwest’s AUS schedule faces short-term equipment pressure while the cause of the debris remains open.

• Check your flight twice before departure: Use the Southwest app or southwest.com the evening before and again two to three hours before you leave for the airport. Look specifically for equipment changes or significant departure time shifts — both signal the airline is working around the grounded aircraft.
• Call, don’t wait in line: If your flight shows a major change, call Southwest at 1-800-435-9792 before heading to the airport. Request a same-day rebooking on an earlier or later departure that fits your plans — Southwest’s customer service policies allow this at no charge when the airline initiates the change.
• Price parallel options now: Use Google Flights to check AUS–PHX fares on American via DFW or United via IAH for your travel dates. If you’re booking new, consider a refundable Southwest fare alongside a backup itinerary — cancel one once your specific departure date looks stable.
• Keep documentation: If you incur meal or accommodation costs due to a Southwest-initiated delay, keep all receipts. Southwest’s customer service policies provide travel credits and, in some cases, expense reimbursement for significant disruptions the airline causes.

Watch: An FAA incident report entry or airworthiness directive referencing CFM56-7B engines on Southwest’s 737NG fleet — expected in the coming weeks — will signal whether this stays a single-aircraft issue or triggers broader inspections. An NTSB decision to open a formal investigation would be a second escalation signal worth tracking.

Questions? Answers.