Development of a Lubrication System for the T800-LHT-800 Turboshaft Engine

Abstract

The T800-LHT-800 is a modern technology 1300 shp (975 kW) class turboshaft engine developed for the U.S. Army’s LH helicopter which has great potential for application in various civil air vehicles. As one of its significant features, the engine has a self-contained dry sump, pressure and temperature regulated, recirculating lubrication system. Contractually specified operational attitude and loss of oil requirements impose considerable complications on the design/development of the T800’s lubrication system. Characteristically, lubrication systems provide cooling and lubrication to all bearings, gears, seal rotors, and working splines at all engine operating conditions. The T800-LHT-800 lubrication system must provide continuous lubrication for an engine operational attitude envelope range of 120 deg noseup, 90 deg nosedown, and 48 deg rolls in either direction. Development of the lubrication system attitude capabilities has been accomplished via testing on a lubrication simulator rig and a series of both development and qualification engine attitude tests. A formal engine attitude qualification test, which will demonstrate both military qualification test (QT) and civil (FAA) certification requirements, will be conducted in 1991. Contractually required engine protection against loss of oil conditions lasting up to six min provided a significant design challenge for the T800 lubrication system and an emergency oil system was designed to meet this requirement. This emergency oil system was developed via multiple design iterations, bench testing on a lubrication simulator rig, and loss of oil development engine testing. As part of the qualification process, a formal qualification loss of oil engine test will be conducted in mid-1991 to verify this design capability. This paper describes the basic T800 engine and discusses the lubrication system requirements. It emphasizes the design evolution of the main oil tank attitude capabilities, the emergency oil system, and the planned qualification/certification testing.