Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Lockheed Model L-1011-385 series airplanes. This proposal would require modification of the high pressure bleed valve controller of each engine. This proposal is prompted by reports of failure of the bleed air system components such as the thermal compensators and bleed air ducts. The actions specified by the proposed AD are intended to prevent such failures of the bleed air system components, which could result in high temperature air leaking into the cabin and/or cargo areas and could possibly require an emergency landing and evacuation.