Airworthiness Directives; Viking Air Limited (Type Certificate Previously Held by Bombardier, Inc. and de Havilland, Inc.) Airplanes

The FAA is superseding Airworthiness Directive (AD) 80-13-10, AD 80-13-12 R1, and AD 2008-03-01, which applied to certain de Havilland (type certificate now held by Viking Air Limited) Model DHC- 6-1, DHC-6-100, DHC-6-200, and DHC-6-300 airplanes. AD 80-13-10 required repetitively inspecting the main landing gear (MLG) legs for cracks and corrosion. AD 80-13-12 R1 required repetitively inspecting each engine nacelle lower longeron for cracks and buckling. AD 2008-03- 01 required incorporating inspections, modifications, and life limits of certain structural components into the aircraft maintenance program. Since the FAA issued those ADs, new and more restrictive airworthiness limitations have been issued for certain structural components. This AD requires incorporating into maintenance records new or revised life limits, modification limits, and inspection or overhaul intervals. The FAA is issuing this AD to address the unsafe condition on these products.