Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to all Short Brothers Model SD3-60 SHERPA series airplanes. This proposal would require repetitive inspections and torque tests for discrepancies of certain bolts and rivets; and related investigative and corrective actions. This action is necessary to detect and correct loose bolts that attach the vertical stabilizer to the horizontal stabilizer, and pulled or loose rivets in the upper shear angles, which could result in reduced structural integrity of the vertical stabilizer. This action is intended to address the identified unsafe condition.