Summary
We propose to adopt a new airworthiness directive (AD) for certain Thrush Aircraft, Inc. (Thrush) Model S2R series airplanes. This proposed AD would require repetitive visual inspections of the vertical and horizontal stabilizer attach fitting, attach fitting bolts, and the vertical fin aft spar for cracks or corrosion and require immediate replacement of cracked or corroded parts and eventual replacement if no cracks or corrosion is found as terminating action for the repetitive inspections. This proposed AD results from reports of cracks in the empennage of Thrush S2R series airplanes. We are proposing this AD to detect and correct these cracks, which could cause the vertical stabilizer to lose structural integrity. This condition could lead to loss of control.