Description

The Gem features a three-shaft configuration with a four-stage low pressure (LP) compressor, driven by a single-stage low pressure (LP) gas generator turbine; an HP centrifugal compressor driven by a single-stage HP gas generator turbine; and a two-stage power turbine driving the output shaft, which passes to the front of the engine. The combustor is reverse flow annular and drive is either through a reduction gearbox, in the case of the Gem 42, or direct for the Gem 1004. The Gem 1004 also features a digital electronic fuel control system.

The Gem was developed for the UK and French governments to power the AgustaWestland Lynx helicopter family. In production since 1976, the Gem series of engines has become highly successful and has been proven in service during the most intensive peacetime and combat operations. The latest Gem 42 turboshaft features improved reliability and power retention compared with previous versions and is fully marinised. The engine's unique two-shaft gas generator gives extremely rapid response with no need for complex variable-geometry blades.

The Gem 42 / AgustaWestland Lynx combination has set the standard for shipborne naval helicopters, with recent sales including orders from South Korea, Portugal, Brazil and Germany. The Gem is still in production, and in 2001 celebrated the double milestone of 25 years of service and 3 million flight hours, 1 million of which have been logged by the Gem 42.

A further development, the Gem 1004, has been developed to power the Agusta A129 Mangusta attack helicopter. Featuring a direct-drive system and uprated emergency power ratings, the Gem 1004 provides the power margins needed to match the agility and manoeuvrability of the A129.