Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to all Short Brothers Model SD3-60 series airplanes. This proposal would require inspection of the welded joints of the balance weight brackets for the left and right elevator trim tabs for cracking; repetitive inspections, as applicable; and corrective actions including the eventual replacement of all brackets, which would constitute terminating action for the repetitive inspections. This action is necessary to prevent the loss of the balance weight for the elevator trim tab, which could result in incorrect trim during takeoff and landing, and reduced controllability of the airplane. This action is intended to address the identified unsafe condition.