Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to all Boeing Model 727 series airplanes. This proposal would require a review of maintenance records or a one-time test to determine if elevator hinge support ribs on the trailing edge of the horizontal stabilizer are made from a certain material, and follow-on repetitive inspections for corrosion or cracking of the elevator hinge support ribs, if necessary. For airplanes with the affected ribs installed, this proposal would eventually require replacement of all affected ribs with new, improved ribs. This action is necessary to prevent cracking of the elevator hinge support ribs, which could lead to vibration of the airframe during flight and consequent damage to the elevator and horizontal stabilizer, potentially resulting in loss of controllability of the airplane. This action is intended to address the identified unsafe condition.