Summary
The FAA proposes to supersede two existing airworthiness directives (ADs) that apply to all Short Brothers Model SD3-60 airplanes. One of the ADs currently requires inspection of the welded joints of the balance weight brackets for the elevator trim tabs for cracking; repetitive inspections, as applicable; and corrective actions including the eventual replacement of all brackets. The other AD currently requires, for certain airplanes, repetitive inspections for cracking of the balance weight brackets and replacement of any cracked bracket, and provides for an optional terminating action for the repetitive inspections. This proposed AD would require an additional inspection to detect cracks of the balance weight brackets, applicable related investigative and corrective actions, and replacement of a certain balance weight bracket when it has reached its maximum life limit. This proposed AD results from a report indicating that several reworked balance weight brackets have exhibited signs of premature failure. We are proposing this AD to prevent failure of the balance weight brackets of the elevator trim tabs, which could cause loss of the balance weight. This could result in incorrect trim during takeoff and landing, and reduced controllability of the airplane.