SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD) for all Textron Aviation Inc. (Textron) (Type Certificate previously held by Cessna Aircraft Company) Models 210N, 210R, P210N, P210R, T210N, T210R, 177, 177A, 177B,
177RG, and F177RG airplanes. This proposed AD was prompted by the in-flight break-up of a Model T210M airplane in Australia, due to fatigue cracking that initiated at a corrosion pit, and subsequent corrosion reports on other Model 210-series and Model 177-series airplanes. This proposed AD would require visual and eddy current inspections of the carry-thru spar lower cap, corrective action if necessary, application of a protective coating and corrosion inhibiting compound (CIC), and reporting the inspection results to the FAA. The FAA is proposing this AD to address the unsafe condition on these products.