EASA AD 26-113 — Engine – High Pressure Turbine Front Seal – Inspection

Summary

EASA Airworthiness Directive Proposal 26-113 is a regulatory document addressing the inspection of the High Pressure Turbine (HPT) front seal on CFM INTERNATIONAL S.A. CFM56-5B and CFM56-7B engine models. These engines are commonly installed on Airbus A318, A319, A320, and A321 series aircraft, as well as Boeing 737-600, 737-700, 737-800, 737-900, and 737-900ER series aircraft. The directive proposes a one-time on-wing borescope inspection to detect potential misalignment and cracks in the HPT front seal to prevent uncontained part release and possible engine or aircraft damage.

What Changed

This new proposed Airworthiness Directive introduces mandatory inspections of the HPT front seal alignment and condition using borescope inspection techniques for affected CFM56-5B and CFM56-7B engines. It defines engine groups based on affected parts and shop visit history and requires corrective actions including part replacement if discrepancies or cracks are found. The directive also provides detailed compliance times based on engine cycles after the effective date.

Why It Matters

This proposal is critical for aviation professionals as it addresses a safety risk related to the potential uncontained release of HPT front seals, which could cause significant engine and aircraft damage. Operators and maintenance organizations must ensure timely inspections and corrective actions to maintain airworthiness and comply with regulatory requirements. Compliance teams need to track affected engine serial numbers and manage inspection schedules to avoid operational disruptions.

What To Do

Affected operators must perform the specified borescope inspections within the compliance times outlined in the directive, which vary by engine group and model. If any misalignment or cracks are detected during inspections, the affected HPT front seal must be replaced with a serviceable part before the next flight. Operators should refer to the applicable CFM Service Bulletins 72-1146 and 72-1117 for detailed inspection and corrective procedures and submit comments on the proposal by 21 October 2026.