What Engine Defect Forced the FAA to Issue a New Boeing 737 MAX Directive?

ByUjjwal Sukhwani•January 16, 2026 at 12:43 PM•3 min read

REGULATORY What Engine Defect Forced the FAA to Issue a New Boeing 737 MAX Directive?

The FAA issued an Airworthiness Directive for specific Boeing 737 MAX models, mandating inspections for a potential engine component defect that could cause engine failure.

Key Points

1The FAA issued an AD on January 15, 2026, targeting CFM LEAP-1B engines on certain Boeing 737 MAX models.
2The core issue is a quality escape involving nonconforming material grain size in the Low-Pressure Turbine (LPT) stage 4 and stage 5 disks.
3The AD mandates the removal and replacement of the affected LPT disks to prevent premature fracture and potential uncontained engine debris release.
4Compliance thresholds vary, requiring action at the next piece-part exposure or before exceeding specific flight cycle limits (2,400 to 19,000 cycles).

The Federal Aviation Administration (FAA) has issued a critical FAA Airworthiness Directive (AD) for certain Boeing 737 MAX engine models. This regulatory action targets a potential engine component defect in the CFM International LEAP-1B turbofans. The AD requires immediate and 737 MAX mandatory inspections to ensure continued operational safety. The directive was officially adopted on January 15, 2026, according to reports.

Key Details of the Airworthiness Directive

The AD is a final rule that applies to specific CFM Model LEAP-1B engines. These engines power the Boeing 737 MAX family of aircraft. The directive addresses a quality escape found in the manufacturing process. This defect involves the low-pressure turbine (LPT) stage 4 and stage 5 disks.

Manufacturer investigation revealed the forgings had a nonconforming material grain size. This material issue can lead to reduced material properties. The unsafe condition could cause premature fracture of the disks. Such a failure presents a severe engine failure risk and could result in uncontained debris release.

Required Actions and Compliance

To mitigate this danger, the AD mandates specific actions for operators. The primary requirement is the removal and replacement of the affected LPT stage 4 and stage 5 disks. This must occur at the next piece-part exposure or before certain flight cycle thresholds are exceeded.

The compliance timeline varies based on the engine's cycles since new.
Thresholds range between 2,400 and 19,000 cycles.
The directive incorporates service bulletin procedures from the engine manufacturer.

Industry Impact and Regulatory Oversight

This Aviation regulatory action affects a significant number of aircraft globally. The CFM LEAP-1B is a crucial engine for the narrow-body market. Airlines operating the 737 MAX must now schedule maintenance to comply with the AD. This creates a notable airline operational impact due to potential groundings for inspections and part replacement.

The AD underscores the FAA's commitment to commercial aviation safety. The European Union Aviation Safety Agency (EASA) often issues similar directives for its registered aircraft. This ensures a unified global approach to safety standards. Boeing and CFM International, a joint venture of GE Aviation and Safran Aircraft Engines, are working closely with regulators. Their cooperation is essential for developing and supplying the necessary replacement parts and service bulletins.

Experts note that ADs are a standard part of aviation life. However, this AD highlights the ongoing scrutiny of the 737 MAX supply chain. The focus remains on maintaining the highest levels of safety for the global fleet.

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