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General Electric plans to certificate an upgraded CJ610 engine in a Learjet 20 as a means of offering the same conversion to the US Air Force for more than 500 Northrop T-38 Talon trainers. This will be as an "off the shelf" procurement.

The unusual plan, thought to be one of the first of its kind, follows extensive revision of US Defense Department procurement policies. It will give GE the added benefit of a qualified commercial upgrade programme. The T-38 update will tackle "corrosion issues" in the aircraft's J85-5 engine, a military version of the early Learjet powerplant, as well as provide a substantial life extension. "It will dramatically reduce the number of parts, and opportunities, for corrosion," says the engine maker.

GE is funding the development of the upgrade package, which centres on a spooled compressor rotor. This will replace the original eight-stage compressor, which consists of a conventional disc and spacer assembly, with an all-new compressor. The upgraded compressor has identical dimensions.

The GE-funded programme is being undertaken "in anticipation of a commercial procurement by the USAF", says the company, which plans to flight test the upgrade on a Learjet in early 2001. The test effort is expected to lead to the award of a supplemental type certificate (STC) from the US Federal Aviation Administration. Although this will theoretically enable Learjet operators to take advantage of the longer-life engine upgrade, GE says it "won't be aggressively marketing it". The STC will be used as the platform for the "off the shelf" procurement of the upgrade by the USAF.

The engine upgrade supplements USAF structures and avionics improvement programmes for the twin-engined T-38.

Source: Flight International