PRODUCT: All Turbomeca S.A. Arriel 2B and 2B1 turboshaft engines. SUBJECT: Airworthiness Directive 2012-08-18 ACTION: Final Rule
SUMMARY: This AD was prompted by the discovery of non-conformities of certain power turbine (PT) blade fir-tree roots. This AD requires removing the affected PT blades from service on or before reaching a new reduced life limit for those certain PT blades. The FAA is issuing this AD to prevent PT blade rupture, which could result in an uncommanded in-flight engine shutdown, forced autorotation landing, or accident.