The National Transportation Safety Board (NTSB) issued a critical safety recommendation on Wednesday.
It addresses the potential risk of smoke entering the cockpit or passenger cabin of airplanes. This is applicable to those aircraft powered by CFM International LEAP-1B engines.
The NTSB also called for further evaluation of LEAP-1A and LEAP-1C engines to determine if they face similar issues.
These engines are commonly found on Airbus A320neo and Boeing 737 Max narrow-body passenger jets. The aircraft variants are in wide usage globally on commercial flight operations.
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Engine Load Reduction Device (LRD)
The concern centers on a component known as the engine load reduction device (LRD). This is a safety feature intended to minimize vibrations from a damaged engine. However, the NTSB discovered that the LRD could harm the engine’s oil system.
When this happens, hot oil can produce smoke that enters the aircraft’s ventilation system, potentially reaching the cockpit or cabin. This poses a serious hazard to flight safety, as smoke can impair visibility and affect crew performance.
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Two Incidents of Concern
The NTSB’s recommendations follow two incident of concern involving Southwest Airlines Boeing 737 MAX 8 aircraft. In December 2023, a flight departing New Orleans, Louisiana, experienced smoke in the cockpit. This occurred after a bird struck the aircraft’s left-hand engine.
The crew reported thick, acrid white smoke that made it difficult for the captain to read the instrument panel.
Following safety procedures, the crew used oxygen masks, cleared the smoke, and safely returned to New Orleans. No injuries were reported among passengers or crew.
A similar event occurred in March 2023, involving a Southwest flight leaving Havana, Cuba. The flight encountered vapor fog in the passenger cabin after birds were ingested into the right-hand engine.
The flight crew declared an emergency and safely landed back at the departure airport. These incidents raised concerns about the risks associated with LRD activation and the potential for smoke to compromise flight operations.
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Recommended Actions
To address this issue, the NTSB urged the Federal Aviation Administration (FAA) to ensure that airlines operating aircraft with CFM LEAP engines inform their flight crews about the hazard.
The agency emphasized the need for crews to understand the steps to mitigate smoke-related events.
Boeing has already updated its flight manuals. These now provide clear instructions for pilots to prevent smoke from spreading into the cockpit or cabin after an LRD activates.
The NTSB also issued recommendations to the FAA, the European Union Aviation Safety Agency (EASA), and the Civil Aviation Administration of China.
These agencies were asked to actively investigate whether LEAP-1A and LEAP-1C engines are vulnerable to similar smoke risks.
Additionally, the NTSB called for the FAA and EASA to mandate software updates developed by CFM and Boeing for all affected engines. These updates aim to reduce the likelihood of smoke entering critical areas of the aircraft.
Conclusion
The full 11-page NTSB investigation report is available online for public review. This report details the incidents and provides technical insights into the LRD-related risks.
The NTSB’s proactive recommendations underscore the importance of addressing potential safety hazards swiftly to protect passengers and crew.
As regulators and manufacturers work to implement these changes, airlines are expected to enhance crew training and adopt the necessary software modifications to ensure safer flights.
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