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T400 / PT6T-3/6

The U.S. Air Force announced a contract in May 1968 for 79 UH-1N's to be used for counter-insurgency (COIN) and "special operational forces" missions. The new variant could carry up to 14 passengers and had twin engine reliability: a Pratt & Whitney T400-CP-400 that consisted of two PT6T turboshafts driving a single rotor through a combining gearbox. Its tail rotor was a tractor rather than a pusher-type and was mounted on the right side of the tail boom, thus distinguishing it from other UH-1 models.

The UH-1N entered the Air Force inventory in 1970 to provide search and rescue capabilities. The missions expanded to include missile support, VIP support, and survival school support. HH-1H and UH-1Fs supporting the missile wings were eventually replaced by the UH-1N due to the greater safety and capability offered by the twin Pratt and Whitney T400-CP-400 twin engine power package, rated at 1800 shaft horsepower. The previous UH-1H was powered by a single Lycoming T53-L-13B 1400 shp turboshaft engine.

The Marines operated armed Hueys in Vietnam, and ordered their own version of the Cobra in May 1968. Featuring the Pratt and Whitney Twinpac T400 engine (two 900-hp turboshaft engines coupled together) giving an overall increase in installed power, the AH-1J Sea Cobra included a new nose turret gun, the three barrel XM-197 20mm and other improvements. In February of 1971 the first AH-1Js arrived in Vietnam for combat evaluation.

For nearly 60 years, NADEP Cherry Point has never lost focus of its central mission -- "Service to the Fleet." Military pilots demand a great deal from their engines, so repairs on these critical parts must be accurate and reliable. The depot's highly skilled artisans completely overhaul, assemble and test a wide range of aircraft engines. As engines and parts are removed from the aircraft, they are routed to the various in-house shops for maintenance. In addition, various engines from the fleet supply system are also refurbished at the depot before they are returned to action. The Industrial Engines Repair and Modification Division overhauls and repairs numerous aircraft engines for a wide variety of military aircraft. This includes the T400 which powers the UH-1 Huey and AH-1 Cobra attack helicopters.

The T400 engine is currently the engine used in circulation for the United States Marine Corps' fleet of UH-1N helicopters. By 2005 this engine had a lot of flight hours and could benefit from an engine upgrade giving the aircraft engine greater maintainability and reliability. With the increase in flight hours, it is inevitable that capacity to repair and overhaul the engine will eventually be exceeded with the current resources available. A project funded under 6DF4EL0212PR will be used to modify the existing engine test cell #2 (00146015084) to obtain newer technology.

The government sought proposals for conversion of the T400 turbo-shaft engine test cell located at the Naval Air Depot, MCAS, Cherry Point, NC from a single engine test system to a Versatile Engine Test System (VETS) facility capable of testing multiple turbo-shaft engine types and models (between 1500 and 5000 SHP) utilizing a removable Engine Test Bed System (ETBS?) designed for each engine type.

Currently, test cell #2 tests T400 engines. For this procurement, hardware and software will be procured and structural revisions will be made to the facility. This modification will improve testing process. One alternative solution was to obtain a portable test cell. There was concern with the short term preparation for any environmental issues that would arise. Also, test cell availability was a concern. Another solution was to send engines to an outside source to test. This method proved to be costly not to mention the security issues that would arise.

If test cell #2 is not modified, the test cell and equipment will continue to age. It will become more difficult to improve the engine performance. This in turn would increase the risk of not having the ability to control turn around time. While the economic payback exceeds 4.5 years and/or the ROR is less than 20%, due to Warfighter mission criticality and capabilities this project supports (and as cited within this Cost Benefit Analysis), the Navy said justification is warranted.

The VETS is an easily configurable, multiple turboshaft engine test cell. This test cell shall automatically, semi-automatically, or manually test the performance characteristics of multiple types of military aircraft turboshaft engines as identified in paragraph 1.0 above, in accordance with the components? associated technical manual. The VETS concept is to develop a universal test bed mounting frame. The mounting frame shall accept an Engine Test Bed System (ETBS). The ETBS shall be built specifically for a particular engine and contain all of the peculiar test hardware required for that engine such as dyno, flywheel, spindles, etc. Test cell utilities shall be designed to be scalable to meet differing engine requirements. The interface connections from the ETBS and the test cell shall be standardized so that all models of ETBS will connect to the facility in the same manner. Furthermore the VETS shall be designed such that it will be versatile enough to accept future engines not defined but within the shaft-horsepower (SHP) range defined in the specification. The only requirements to add a new engine type will be the manufacture of a new ETBS and Test Program Set (TPS).




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