Summary
The FAA proposes to supersede Airworthiness Directive (AD) 80- 13-10, AD 80-13-12 R1, and AD 2008-03-01, which apply 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 requires repetitively inspecting the main landing gear (MLG) legs for cracks and corrosion. AD 80-13-12 R1 requires repetitively inspecting each engine nacelle lower longeron for cracks and buckling. AD 2008-03- 01 requires 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 proposed AD would require incorporating into maintenance records new or revised life limits, modification limits, and inspection or overhaul intervals. The FAA is proposing this AD to address the unsafe condition on these products.