Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain McDonnell Douglas Model DC-9, DC-9-80 and C-9 (military) series airplanes, and Model MD-88 airplanes. This proposal would require revising the wiring of the air conditioning pneumatic supply control, if applicable, and revising the wiring of the pneumatic augmentation valve. This proposal is prompted by a report indicating that the pneumatic augmentation valve may go fully open when an engine fails during initial climb prior to deactivation of the second segment climb switch. The actions specified by the proposed AD are intended to prevent opening of the pneumatic augmentation valve, which could result in significant loss of thrust from the remaining engine and consequent inadequate initial climb performance of the airplane.