Gem banner .png file (630x380)
  • More than 1,100 produced

  • Operated by 13 military customers in 12 nations

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

The Gem 42/AgustaWestland Lynx combination has set the standard for shipborne naval helicopters. The engine celebrated its double milestone of 25 years of service and three million flight hours in 2001, one million of which were logged by the Gem 42.

The most recent variant, Gem 1004, was developed to power the Agusta A129 Mangusta attack helicopter. Featuring a direct-drive system and uprated emergency power ratings, the Gem 1004 provides power margins needed to match the agility and maneuverability of the A129.

The Gem features a 3-shaft configuration with a 4-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 2-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 or direct. The Gem 1004 features a digital electronic fuel control system.


Gem 42

Power (shp)


Bypass ratio


Pressure ratio


Length (in)


Diameter (in)


Basic weight (lb)





1HP, 1LP, 2PT


AgustaWestland Lynx, Agusta A129 Mangusta

*Technical data (ISA SLS)