TO THE FEDERAL AVIATION ADMINISTRATION, THE EUROPEAN UNION AVIATION SAFETY AGENCY, AND THE CIVIL AVIATION ADMINISTRATION OF CHINA: Work with CFM International, Airbus, and the Commercial Aircraft Corporation of China to determine if CFM International LEAP-1A or -1C engines are at risk of smoke in the cockpit or cabin as a result of load reduction device activation and require affected operators to incorporate any modification that results.
Safety Issue and Context
The National Transportation Safety Board (NTSB) is providing the following information to urge the Federal Aviation Administration (FAA), the European Union Aviation Safety Agency (EASA), the Civil Aviation Administration of China (CAAC), CFM International, and Boeing to take action on safety recommendations in this report. These recommendations address the potential for smoke to enter the cockpit or cabin after activation of the load reduction device (LRD) resulting from an engine blade failure or imbalance on CFM LEAP-1B engines and pilot awareness about what to do if this occurs.
We identified this issue during our ongoing investigation of an incident involving Southwest Airlines flight 554, a Boeing 737-8, in which smoke filled the cockpit after a bird was ingested into the left (No. 1) engine, a CFM LEAP-1B. The NTSB is issuing an urgent safety recommendation to the FAA. In addition, we are issuing two safety recommendations to the FAA and EASA and one safety recommendation each to Boeing, CFM International, and the CAAC.
Response History
April 15, 2026 · NTSB Correspondence · European Aviation Safety Agency
We note that EASA is working with CFMI, Airbus, COMAC, and associated regulatory agencies to determine if CFMI LEAP 1A and LEAP 1C engines are at risk of producing smoke in the cockpit or cabin when the LRD has been activated, and to determine if operators should be required to implement any resulting design or maintenance modifications.
We look forward to reviewing the findings of your evaluation and completion of the recommended actions. In the meantime, the Board has voted to classify Safety Recommendation A-25-12 OPEN-- ACCEPTABLE RESPONSE.
March 11, 2026 · NTSB Correspondence · FAA
On August 15, 2025, FAA Administrator Bryan Bedford informed us that Safety Recommendations A-25-11 and -12 had been assigned to the FAA's Aircraft Certification Service to determine the best course of action. These recommendations are currently classified Open-Initial Response Received. We look forward to receiving more detailed information about the FAA's plans for addressing these recommendations in its next update, which Administrator Bedford reported would be provided by the end of August 2026. The Board will classify the response at that time.
August 29, 2025 · Recipient Response · European Aviation Safety Agency
-From Pierluca Satriano, Head of Safety Intelligence and Performance Department: The European Union Aviation Safety Agency (EASA) is working with CFM International, Airbus, COMAC and associated Regulatory Agencies to determine the level of risk presented by smoke in the cockpit or cabin as a result of load reduction device activation on CFM International LEAP-1A or -1C engines and assess the need to require the incorporation of any modification that results, for affected operators.
August 15, 2025 · Recipient Response · FAA
-From Bryan Bedford, Administrator: The FAA’s Aircraft Certification Service is reviewing the NTSB report internally to determine a plan forward to address the safety recommendations.
I anticipate providing an update to these safety recommendations by August 31, 2026.
June 18, 2025 · NTSB Correspondence · FAA
This letter provides information about the National Transportation Safety Board’s (NTSB) June 18, 2025, report Mitigations Concerning Load Reduction Device Activation in CFM International LEAP-1B Engines, AIR-25-03. The details of relevant accident investigations and the resulting safety recommendations may be found in the attached report, which can also be accessed at http://www.ntsb.gov.
As a result of this investigation, we identified the following safety issues:
• As currently designed, load reduction device (LRD) activation in LEAP-1B engines (and potentially LEAP-1A and -1C engines) may damage an oil component and allow smoke to enter the cockpit or cabin of the airplane.
• Pilots who fly airplanes equipped with affected engines may not be aware of this potential for smoke in the cockpit or cabin as a result of LRD activation or the actions they should take if it should occur.
Accordingly, the NTSB makes the following safety recommendations to the FAA:
• Ensure operators inform flight crews of airplanes equipped with CFM International LEAP-1B engines of the circumstances described in National Transportation Safety Board Aviation Investigation Report AIR-25-03, emphasizing Boeing’s changes to the quick reference handbook and flight crew operations manual so pilots are aware of actions to take if they encounter smoke in the cockpit or cabin after load reduction device activation. (A-25-10) Urgent
• Once CFM International and Boeing complete the development and certification process for software modifications to the CFM International LEAP-1B engines, require all operators of airplanes equipped with CFM International LEAP-1B engines to incorporate the software modification developed in response to Safety Recommendations A-25-13 and A 25 14 to prevent or limit the amount of smoke released into the cockpit or cabin after load reduction device activation. (A-25-11)
• Work with CFM International, Airbus, and the Commercial Aircraft Corporation of China to determine if CFM International LEAP-1A or -1C engines are at risk of smoke in the cockpit or cabin as a result of load reduction device activation and require affected operators to incorporate any modification that results. (A-25-12)
June 18, 2025 · NTSB Correspondence · European Aviation Safety Agency
This letter provides information about the National Transportation Safety Board’s (NTSB) June 18, 2025, report Mitigations Concerning Load Reduction Device Activation in CFM International LEAP-1B Engines, AIR-25-03. The details of relevant accident investigations and the resulting safety recommendations may be found in the attached report, which can also be accessed at http://www.ntsb.gov.
As a result of this investigation, we identified the following safety issues:
• As currently designed, load reduction device (LRD) activation in LEAP-1B engines (and potentially LEAP-1A and -1C engines) may damage an oil component and allow smoke to enter the cockpit or cabin of the airplane.
• Pilots who fly airplanes equipped with affected engines may not be aware of this potential for smoke in the cockpit or cabin as a result of LRD activation or the actions they should take if it should occur.
Accordingly, the NTSB makes the following safety recommendations to the EASA:
• Once CFM International and Boeing complete the development and certification process for software modifications to the CFM International LEAP-1B engines, require all operators of airplanes equipped with CFM International LEAP-1B engines to incorporate the software modification developed in response to Safety Recommendations A-25-13 and A 25 14 to prevent or limit the amount of smoke released into the cockpit or cabin after load reduction device activation. (A-25-11)
• Work with CFM International, Airbus, and the Commercial Aircraft Corporation of China to determine if CFM International LEAP-1A or -1C engines are at risk of smoke in the cockpit or cabin as a result of load reduction device activation and require affected operators to incorporate any modification that results. (A-25-12)
The NTSB is vitally interested in these recommendations because they are designed to prevent accidents and save lives. We would appreciate a response within 90 days of the date of this letter, detailing the actions you have taken or intend to take to implement this urgent recommendation. When replying, please refer to the safety recommendation by number (Safety Recommendations A-25-11 and -12). We encourage you to submit your response to ExecutiveSecretariat@ntsb.gov. If your reply, including attachments, exceeds 20 megabytes, please e mail us at the same address for instructions on how to send larger documents.
June 18, 2025 · NTSB Correspondence · Foreign, China, Civil Aviation Administration of China
This letter provides information about the National Transportation Safety Board’s (NTSB) June 18, 2025, report Mitigations Concerning Load Reduction Device Activation in CFM International LEAP-1B Engines, AIR-25-03. The details of relevant accident investigations and the resulting safety recommendations may be found in the attached report, which can also be accessed at http://www.ntsb.gov.
As a result of this investigation, we identified the following safety issues:
• As currently designed, load reduction device (LRD) activation in LEAP-1B engines (and potentially LEAP-1A and -1C engines) may damage an oil component and allow smoke to enter the cockpit or cabin of the airplane.
• Pilots who fly airplanes equipped with affected engines may not be aware of this potential for smoke in the cockpit or cabin as a result of LRD activation or the actions they should take if it should occur.
Accordingly, the NTSB makes the following safety recommendation to the CAAC:
Work with CFM International, Airbus, and the Commercial Aircraft Corporation of China to determine if CFM International LEAP-1A or 1C engines are at risk of smoke in the cockpit or cabin as a result of load reduction device activation and require affected operators to incorporate any modification that results. (A-25-12)
The NTSB is vitally interested in this recommendation because it is designed to prevent accidents and save lives. We would appreciate a response within 90 days of the date of this letter, detailing the actions you have taken or intend to take to implement this recommendation. When replying, please refer to the safety recommendation by number (Safety Recommendation A-25-12). We encourage you to submit your response to ExecutiveSecretariat@ntsb.gov. If your reply, including attachments, exceeds 20 megabytes, please e mail us at the same address for instructions on how to send larger documents. Please do not submit both an electronic copy and a hard copy of the same response.
From the aviation investigation report AIR-25-03 “Mitigations Concerning Load Reduction Device Activation in CFM International LEAP-1B Engines”
The NTSB is vitally interested in these recommendations because they are designed to prevent accidents and save lives. We would appreciate a response within 30 days of the date of this letter, detailing the actions you have taken or intend to take to implement the urgent recommendation (Safety Recommendation A-25-10). Please respond within 90 days of the date of this letter regarding the other two recommendations (Safety Recommendations A-25-11 and A-25-12). When replying, please refer to the safety recommendation by number (for example, Safety Recommendation A-25-10) and submit your response to ExecutiveSecretariat@ntsb.gov.
If your reply, including attachments, exceeds 20 megabytes, please e mail us at the same address for instructions on how to send larger documents. Please do not submit both an electronic copy and a hard copy of the same response.
From the aviation investigation report AIR-25-03 “Mitigations Concerning Load Reduction Device Activation in CFM International LEAP-1B Engines”
Background and Analysis
On December 20, 2023, about 1414 central standard time, Southwest Airlines flight 554, a Boeing 737-8, was departing from Louis Armstrong New Orleans International Airport (MSY), Kenner, Louisiana, when a bird was ingested into the left (No. 1) engine, a CFM International LEAP-1B, during the initial climb (figure 1 shows damage to the engine).
The flight crew reported that, after an uneventful takeoff and while climbing through about 1,000 ft, the first officer (FO), who was the pilot monitoring, heard the captain say “bird.” This statement was followed immediately by a “thump” on the left side of the airplane. The flight crew reported that the airplane began to “shake violently with a distinct loss of thrust” in the No. 1 engine.
The captain called for the Engine Fire or Engine Severe Damage or Separation checklist in the Quick Reference Card (QRC). After the FO started the checklist, the flight deck filled with “acrid white smoke”; the FO later stated that he could not clearly see the captain. The FO called out “masks” and the pilots donned their masks and resumed the checklist.
The flight crew declared an emergency to air traffic control and asked airport rescue and firefighting to “roll the trucks.” The captain stated that visibility in the cockpit was restricted and that he could see nothing beyond the FO. The captain also stated that his instrument panel was difficult to see, so he thought he might need to fly the airplane solely using the head-up guidance system. However, after the FO pulled the engine fire switch as directed by the QRC, the smoke began to rapidly dissipate.
The flight crew notified the flight attendants about the emergency and made a public address announcement to passengers that fire trucks would be meeting the airplane. After landing at MSY, the airplane came to a full stop on the arrival runway. After inspecting the airplane, the firefighters found no evidence of a fire. The flight crew was cleared to taxi the airplane to the assigned gate and passengers deplaned normally without further incident. None of the 139 occupants aboard the airplane were injured, and the airplane sustained minor damage.
The flight was operating under the provisions of Title 14 Code of Federal Regulations Part 121 as a scheduled domestic passenger flight from MSY to Tampa International Airport, Tampa, Florida.
According to the regulations requiring immediate reporting to the NTSB (at Title 49 Code of Federal Regulations 830.5, Immediate Notification), Southwest Airlines was not required to report the incident. Once informed by the FAA in November 2024 about its ongoing investigation of the incident, and, in learning of similarities to a March 2023 event in Havana, Cuba, the NTSB began an incident investigation. Preliminary findings from our ongoing investigation indicate that smoke entered the cockpit as a result of the activation of the LRD, an engine system design feature on CFM International LEAP-1B engines.
The LRD minimizes aircraft and engine damage during a fan blade failure or significant fan blade imbalance by reducing the severity of the vibration transmitted from the damaged engine to the airframe (see figure 2). The LRD does this by enabling the fan to be partially mechanically disconnected from the turbomachinery. As a mechanical design feature, the LRD does not require pilot intervention to activate.
Activation of the LRD in the MSY event caused tubes supplying oil to the engine sump to become dislodged and the flange from the sump area to open, which allowed oil to enter the core compressor upstream of the pneumatic bleed ports that supply bleed air to the cabin and cockpit. The oil was exposed to high temperatures and resulted in smoke and fumes that were then fed into the cockpit. When the FO pulled the engine fire switch, the smoke quickly dissipated because its point of access, the pressure regulating shutoff valve (PRSOV), automatically closed. Each engine has a PRSOV that, when closed, prevents bleed air from entering the airplane (see figure 3).
Boeing released a flight crew operations manual (FCOM) bulletin on February 9, 2024, that described the results of the bird ingestion in the MSY incident and the actions a flight crew should take if they experience a similar incident. Boeing also updated the system description in the Boeing 737-8 FCOM on November 15, 2024, and the quick reference handbook (QRH) on November 30, 2024, to include engine failure with smoke or fumes in the flight deck or cabin as a condition to trigger reference to the Engine Fire or Engine Severe Damage or Separation QRC.
In addition, on February 14, 2024, Southw
Please do not submit both an electronic copy and a hard copy of the same response.
From the aviation investigation report AIR-25-03 “Mitigations Concerning Load Reduction Device Activation in CFM International LEAP-1B Engines”
Background and Analysis
On December 20, 2023, about 1414 central standard time, Southwest Airlines flight 554, a Boeing 737-8, was departing from Louis Armstrong New Orleans International Airport (MSY), Kenner, Louisiana, when a bird was ingested into the left (No. 1) engine, a CFM International LEAP-1B, during the initial climb (figure 1 shows damage to the engine). The flight crew reported that, after an uneventful takeoff and while climbing through about 1,000 ft, the first officer (FO), who was the pilot monitoring, heard the captain say “bird.” This statement was followed immediately by a “thump” on the left side of the airplane.
The flight crew reported that the airplane began to “shake violently with a distinct loss of thrust” in the No. 1 engine.
The captain called for the Engine Fire or Engine Severe Damage or Separation checklist in the Quick Reference Card (QRC). After the FO started the checklist, the flight deck filled with “acrid white smoke”; the FO later stated that he could not clearly see the captain. The FO called out “masks” and the pilots donned their masks and resumed the checklist.
The flight crew declared an emergency to air traffic control and asked airport rescue and firefighting to “roll the trucks.” The captain stated that visibility in the cockpit was restricted and that he could see nothing beyond the FO. The captain also stated that his instrument panel was difficult to see, so he thought he might need to fly the airplane solely using the head-up guidance system. However, after the FO pulled the engine fire switch as directed by the QRC, the smoke began to rapidly dissipate.
The flight crew notified the flight attendants about the emergency and made a public address announcement to passengers that fire trucks would be meeting the airplane. After landing at MSY, the airplane came to a full stop on the arrival runway. After inspecting the airplane, the firefighters found no evidence of a fire. The flight crew was cleared to taxi the airplane to the assigned gate and passengers deplaned normally without further incident. None of the 139 occupants aboard the airplane were injured, and the airplane sustained minor damage.
The flight was operating under the provisions of Title 14 Code of Federal Regulations Part 121 as a scheduled domestic passenger flight from MSY to Tampa International Airport, Tampa, Florida.
According to the regulations requiring immediate reporting to the NTSB (at Title 49 Code of Federal Regulations 830.5, Immediate Notification), Southwest Airlines was not required to report the incident. Once informed by the FAA in November 2024 about its ongoing investigation of the incident, and, in learning of similarities to a March 2023 event in Havana, Cuba, the NTSB began an incident investigation. Preliminary findings from our ongoing investigation indicate that smoke entered the cockpit as a result of the activation of the LRD, an engine system design feature on CFM International LEAP-1B engines.
The LRD minimizes aircraft and engine damage during a fan blade failure or significant fan blade imbalance by reducing the severity of the vibration transmitted from the damaged engine to the airframe (see figure 2). The LRD does this by enabling the fan to be partially mechanically disconnected from the turbomachinery. As a mechanical design feature, the LRD does not require pilot intervention to activate.
Activation of the LRD in the MSY event caused tubes supplying oil to the engine sump to become dislodged and the flange from the sump area to open, which allowed oil to enter the core compressor upstream of the pneumatic bleed ports that supply bleed air to the cabin and cockpit. The oil was exposed to high temperatures and resulted in smoke and fumes that were then fed into the cockpit. When the FO pulled the engine fire switch, the smoke quickly dissipated because its point of access, the pressure regulating shutoff valve (PRSOV), automatically closed. Each engine has a PRSOV that, when closed, prevents bleed air from entering the airplane (see figure 3).
Boeing released a flight crew operations manual (FCOM) bulletin on February 9, 2024, that described the results of the bird ingestion in the MSY incident and the actions a flight crew should take if they experience a similar incident. Boeing also updated the system description in the Boeing 737-8 FCOM on November 15, 2024, and the quick reference handbook (QRH) on November 30, 2024, to include engine failure with smoke or fumes in the flight deck or cabin as a condition to trigger reference to the Engine Fire or Engine Severe Damage or Separation QRC.
In addition, on February 14, 2024, Southwest Airlines issued a Read Before Fly brief to its pilots describing the event and incorporating Boeing’s updates from its FCOM bulletin. The brief indicated that section 5.5.4 Engine Failure or Shutdown in the aircraft operating manual would be updated to indicate that if smoke enters the flight deck or cabin, flight crews should accomplish the Engine Fire or Engine Severe Damage or Separation steps of the QRC.
Southwest’s brief also described the similar event in Havana, Cuba, involving Southwest Airlines flight 3923. Shortly after its departure, birds struck the airplane’s right LEAP-1B engine
Background and Analysis
On December 20, 2023, about 1414 central standard time, Southwest Airlines flight 554, a Boeing 737-8, was departing from Louis Armstrong New Orleans International Airport (MSY), Kenner, Louisiana, when a bird was ingested into the left (No. 1) engine, a CFM International LEAP-1B, during the initial climb (figure 1 shows damage to the engine). The flight crew reported that, after an uneventful takeoff and while climbing through about 1,000 ft, the first officer (FO), who was the pilot monitoring, heard the captain say “bird.” This statement was followed immediately by a “thump” on the left side of the airplane.
The flight crew reported that the airplane began to “shake violently with a distinct loss of thrust” in the No. 1 engine.
The captain called for the Engine Fire or Engine Severe Damage or Separation checklist in the Quick Reference Card (QRC). After the FO started the checklist, the flight deck filled with “acrid white smoke”; the FO later stated that he could not clearly see the captain. The FO called out “masks” and the pilots donned their masks and resumed the checklist.
The flight crew declared an emergency to air traffic control and asked airport rescue and firefighting to “roll the trucks.” The captain stated that visibility in the cockpit was restricted and that he could see nothing beyond the FO. The captain also stated that his instrument panel was difficult to see, so he thought he might need to fly the airplane solely using the head-up guidance system. However, after the FO pulled the engine fire switch as directed by the QRC, the smoke began to rapidly dissipate.
The flight crew notified the flight attendants about the emergency and made a public address announcement to passengers that fire trucks would be meeting the airplane. After landing at MSY, the airplane came to a full stop on the arrival runway. After inspecting the airplane, the firefighters found no evidence of a fire. The flight crew was cleared to taxi the airplane to the assigned gate and passengers deplaned normally without further incident. None of the 139 occupants aboard the airplane were injured, and the airplane sustained minor damage.
The flight was operating under the provisions of Title 14 Code of Federal Regulations Part 121 as a scheduled domestic passenger flight from MSY to Tampa International Airport, Tampa, Florida.
According to the regulations requiring immediate reporting to the NTSB (at Title 49 Code of Federal Regulations 830.5, Immediate Notification), Southwest Airlines was not required to report the incident. Once informed by the FAA in November 2024 about its ongoing investigation of the incident, and, in learning of similarities to a March 2023 event in Havana, Cuba, the NTSB began an incident investigation. Preliminary findings from our ongoing investigation indicate that smoke entered the cockpit as a result of the activation of the LRD, an engine system design feature on CFM International LEAP-1B engines.
The LRD minimizes aircraft and engine damage during a fan blade failure or significant fan blade imbalance by reducing the severity of the vibration transmitted from the damaged engine to the airframe (see figure 2). The LRD does this by enabling the fan to be partially mechanically disconnected from the turbomachinery. As a mechanical design feature, the LRD does not require pilot intervention to activate.
Activation of the LRD in the MSY event caused tubes supplying oil to the engine sump to become dislodged and the flange from the sump area to open, which allowed oil to enter the core compressor upstream of the pneumatic bleed ports that supply bleed air to the cabin and cockpit. The oil was exposed to high temperatures and resulted in smoke and fumes that were then fed into the cockpit. When the FO pulled the engine fire switch, the smoke quickly dissipated because its point of access, the pressure regulating shutoff valve (PRSOV), automatically closed. Each engine has a PRSOV that, when closed, prevents bleed air from entering the airplane (see figure 3).
Boeing released a flight crew operations manual (FCOM) bulletin on February 9, 2024, that described the results of the bird ingestion in the MSY incident and the actions a flight crew should take if they experience a similar incident. Boeing also updated the system description in the Boeing 737-8 FCOM on November 15, 2024, and the quick reference handbook (QRH) on November 30, 2024, to include engine failure with smoke or fumes in the flight deck or cabin as a condition to trigger reference to the Engine Fire or Engine Severe Damage or Separation QRC.
In addition, on February 14, 2024, Southwest Airlines issued a Read Before Fly brief to its pilots describing the event and incorporating Boeing’s updates from its FCOM bulletin. The brief indicated that section 5.5.4 Engine Failure or Shutdown in the aircraft operating manual would be updated to indicate that if smoke enters the flight deck or cabin, flight crews should accomplish the Engine Fire or Engine Severe Damage or Separation steps of the QRC.
Southwest’s brief also described the similar event in Havana, Cuba, involving Southwest Airlines flight 3923. Shortly after its departure, birds struck the airplane’s right LEAP-1B engine, resulting in activation of the LRD and vapor fog entering the passenger cabin. The flight crew declared an emergency and returned to the airport, where they landed without further incident.
The NTSB is aware that CFM International, in collaboration with Boeing, has begun work on an engine software design update that they anticipate completing in the first quarter of 2026. The update will mitigate the presence of smoke or fumes in the cockpit or airplane cabin by closing the PRSOV when the LRD