Airworthiness Directives; Airbus Helicopters Deutschland GmbH (Previously Eurocopter Deutschland GmbH)

We propose to supersede Airworthiness Directive (AD) 97-26-03 for Eurocopter Deutschland GmbH Model MBB-BK 117 A-1, MBB-BK 117 A-3, MBB-BK 117 A-4, MBB-BK 117 B-1, MBB-BK 117 B-2, and MBB-BK 117 C-1 helicopters. AD 97-26-03 requires visual inspections for cracks in the ribbed area of the main rotor (M/R) mast flange (flange). Since we issued AD 97-26-03, we have determined that a certain reinforced M/R mast is not affected by the unsafe condition. This proposed AD would retain the requirements of AD 97-26-03 and would remove a certain M/R mast from the applicability. The actions of this proposed AD are intended to address an unsafe condition on these products.