Summary
The FAA proposes to supersede an existing airworthiness directive (AD) that applies to all Model 750 airplanes. The existing AD currently requires inspecting the inboard-hinge brackets of the left and right elevators for cracking and doing related investigative and corrective actions if necessary. For certain airplanes, this proposed AD would require inspecting for cracks and corrosion of the bracket of the inboard horizontal stabilizer and measuring the lug thickness of the horizontal stabilizer hinges; doing corrective actions if necessary; modifying the left and right elevators and left and right horizontal stabilizer. For all airplanes, this proposed AD would require replacing the existing elevator assemblies with new elevator assemblies, which would terminate the requirements of the existing AD. This proposed AD would also revise the applicability to remove certain airplanes. This proposed AD results from a report of cracking and corrosion found on the elevator inboard-hinge brackets and the horizontal stabilizer hinges. We are issuing this AD to prevent such cracking and corrosion of the elevator inboard-hinge brackets and the horizontal stabilizer hinges, which could result in structural failure of the elevators and consequent loss of control of the airplane.