Airworthiness Directives; Turbomeca S.A. Arriel 1 Turboshaft Engines

This amendment adopts a new airworthiness directive (AD) that is applicable to Turbomeca S.A. Arriel 1 series turboshaft engines. This amendment requires initial and repetitive visual inspections for ingestive erosion, and cleaning if necessary, of M02 and M03 modules. This amendment is prompted by reports from the manufacturer of an unbalance due to accumulation of dust in the M03 module. The actions specified by this AD are intended to prevent an unbalance of the gas generator rotating assembly which may lead to deterioration of the gas generator rear bearing and uncommanded engine shutdown.