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Rolls-Royce / Turbomeca RTM322

Safran Helicopter Engines (formerly Rolls-Royce Turbomeca) · Aircraft Engine · United Kingdom / France · Cold War (1970–1991)

Rolls-Royce / Turbomeca RTM322 — Aircraft Engine
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The Rolls-Royce / Turbomeca RTM322 is the Anglo-French heavy-lift helicopter turboshaft engine that powers the AgustaWestland AW101 Merlin, the NHIndustries NH90, the Eurocopter Tiger attack helicopter, and several other European rotorcraft. Designed in the early 1980s by Rolls-Royce Turbomeca Limited — a 50:50 joint venture between Rolls-Royce (UK) and Turbomeca (France, now Safran Helicopter Engines) — the engine first ran in 1984, certified in 1988, and entered service in 1992 on the Royal Navy's Merlin HM1 anti-submarine helicopter. In 2014 Rolls-Royce sold its share of the joint venture to Safran, and the RTM322 is now produced and supported solely by Safran Helicopter Engines at Bordes, in southwestern France.

The architecture is a free-turbine design: a three-stage axial LP compressor, a single-stage centrifugal HP compressor, an annular combustor, a two-stage HP turbine driving the compressor, and a two-stage free power turbine driving the rotor shaft through a reduction gearbox. FADEC controls fuel scheduling and the engine's automatic emergency mode if the other engine fails. Pressure ratio is around 14.7:1 and the engine masses around 240 kg (529 lb). Thrust-to-weight ratio places it competitively against the U.S. General Electric T700 family — both engines fall in the 2,000-2,500 shp band and are direct rivals for the same heavy-lift helicopter requirements.

Several power variants were developed across the 1990s and 2000s. The baseline RTM322 Mk 250 delivered around 2,100 shp at take-off; the Mk 302 lifted this to around 2,270 shp for the AW101 Merlin and NH90; the Mk 312 reached around 2,425 shp for the AW101 Mk 4 and the Indian Navy's AW101 ASW order. The most powerful variant, the RTM322 Mk 402, has been tested at around 2,650 shp but production has not yet matched that figure. All variants share the same core architecture, allowing operators to upgrade between standards without major airframe modification — a feature that has kept the engine attractive across a 30-year production run.

Operators include the UK Royal Navy and RAF (AW101 Merlin HM1/HM2 and HC3/HC4), the Royal Danish Navy (AW101 SAR), the Italian Navy (AW101), the Japanese Maritime Self-Defense Force (AW101), the Algerian Air Force, and the entire NH90 customer set — Germany, France, Italy, the Netherlands, Norway, Sweden, Finland, Belgium, Spain, Portugal, Greece, Australia (originally; replaced from 2024), New Zealand, Oman, and Qatar. The Tiger HAP / HAD operators (France, Germany, Spain, Australia) also fly the engine, although Australia has retired its Tiger ARH fleet by 2026 in favour of the AH-64E. Across all airframes, more than 3,500 RTM322s have been built — comfortably outproducing the joint venture's original projection from the 1980s.

Production continues at Bordes with no immediate succession plan. Safran's longer-term roadmap for the 2030s pairs the RTM322 with the new Aneto-class engine (in the 2,500-3,000 shp band) and a hybrid-electric demonstrator programme for vertical-lift. The RTM322 will continue to be manufactured and overhauled through at least the 2040s under fleet-support contracts, with the largest customers — Italy, Germany, and France — committed to NH90 and Merlin retention into the late 2040s.

For Kids — a shorter, friendlier version

The RTM322 is a powerful engine made for large helicopters. It was designed together by a British company called Rolls-Royce and a French company called Turbomeca. That kind of teamwork between two countries makes it an Anglo-French engine. Today, a company called Safran builds and looks after it in France.

The engine first ran in 1984 and was ready to fly by 1992. It went to work on a Royal Navy helicopter called the Merlin. That helicopter hunted submarines hiding under the sea. The engine has been very popular since then, with over 3,500 built!

The RTM322 powers some famous helicopters. These include the AW101 Merlin, the NH90, and the Eurocopter Tiger. Each of these helicopters does an important job, from carrying troops to helping out at sea. The engine gives them plenty of power to lift heavy loads.

Inside the engine, air is squeezed and mixed with fuel, then burned to make spinning power. A smart computer called FADEC watches over the engine. If one engine has a problem, FADEC helps the other engine take over right away. The engine weighs about 240 kg, which is heavier than a large motorcycle.

Fun Facts

  • The RTM322 first ran all the way back in 1984 — that's over 40 years ago!
  • More than 3,500 of these engines have been built so far.
  • The engine is heavier than a large motorcycle, tipping the scales at about 240 kg.
  • It was made by two companies from two different countries working together 50-50.
  • A smart computer called FADEC keeps the engine running safely at all times.
  • The engine powers the NH90, one of the most widely used military helicopters in Europe.
  • Safran now builds the RTM322 in a town called Bordes in southwestern France.
  • The Royal Navy was the first to fly a helicopter with this engine back in 1992.

Kids’ Questions

Who made the RTM322 engine?

It was made by Rolls-Royce from Britain and Turbomeca from France. They each owned half of the project. Today, a French company called Safran builds the engine on its own.

Which helicopters use the RTM322?

The RTM322 powers the AW101 Merlin, the NH90, and the Eurocopter Tiger. These are large and important helicopters used across Europe. They carry out many jobs, like sea patrols and carrying soldiers.

What does FADEC do?

FADEC is a smart computer inside the engine. It controls how fuel is used and keeps everything running smoothly. If one engine stops working, FADEC helps the other engine handle the load right away.

When did the RTM322 first fly on a real helicopter?

The engine entered service in 1992 on a Royal Navy helicopter called the Merlin HM1. That helicopter was used to find submarines under the sea. It was a very important first mission for the new engine.

Variants

RTM322 Mk 250 (initial)
First production variant from 1992. Around 2,100 shp take-off rating. Powered early Royal Navy Merlin HM1 and EH101 utility helicopters. Withdrawn from production in favour of higher-rated variants by the late 1990s.
RTM322 Mk 302
Late-1990s upgrade to around 2,270 shp through revised HP turbine cooling and an updated FADEC. Standard powerplant for the AW101 Merlin HM2 and the NH90's later production batches. The most-built variant of the family.
RTM322 Mk 312
Higher-rated 2,425 shp variant introduced for the AW101 Mk 4 (Royal Navy Crowsnest AEW) and Indian Navy AW101 ASW orders, along with the Norwegian SAR Queen fleet. Improved hot-section cooling permits the higher rating without overhaul-interval impact.
RTM322 Mk 402 (development)
Highest-rated variant tested at around 2,650 shp under Safran's growth programme. Targeted at heavier future helicopter requirements but not yet in series production as of 2026.

Notable Operators

AW101 Merlin family
Three RTM322 engines per airframe across all variants. Royal Navy Merlin HM1/HM2, Royal Air Force Merlin HC3/HC4, Italian Navy Merlin, Royal Danish Navy SAR, Norwegian SAR Queen, Japanese MCH-101, Indian Navy MH-101, and Algerian Air Force AW101 deliveries.
NHIndustries NH90
Two RTM322 engines per airframe. Used by Germany, France, Italy, the Netherlands, Norway, Sweden, Finland, Belgium, Spain, Portugal, Greece, New Zealand, Oman, and Qatar. Australia has retired its NH90 (MRH-90 Taipan) fleet from 2024 due to availability problems.
Eurocopter Tiger HAP / HAD
Two MTR390 engines per airframe — a separate but RTM322-derived engine family built by MTU Turbomeca Rolls-Royce GmbH. Operators include France, Germany, and Spain. Australia retired its Tiger ARH in 2025 in favour of the AH-64E Apache Guardian.
Other helicopter operators
Some early Sikorsky S-70B Seahawk and South Korean Surion KUH-1 prototypes used RTM322 development variants before settling on T700 production engines. Industrial RTM322 marine and pumping installations also exist in small numbers.

Frequently Asked Questions

How does the RTM322 compare with the General Electric T700?

Both are 2,000-2,500 shp free-turbine helicopter engines in the same product class and they often compete directly for major rotorcraft requirements. The T700 powers most U.S. helicopters (Black Hawk, Apache, Seahawk) while the RTM322 powers the corresponding European platforms (NH90, AW101, Merlin). The RTM322 runs a higher pressure ratio (around 14.7:1 versus 17.5:1 on the T700-701D — actually the T700 is higher) and is roughly 5% lighter at equivalent rating, while the T700 has a longer production history and a larger spares pool (per Safran Helicopter Engines' RTM322 page).

Why did Rolls-Royce sell its half of the RTM322 to Safran in 2014?

The 2014 sale closed Rolls-Royce's exit from the helicopter-engine market, allowing the company to focus its defence engine portfolio on fixed-wing fighter and transport applications (the EJ200, RB199, Trent family, and the F130). For Safran, full ownership consolidated its position as Europe's dominant helicopter-engine supplier alongside its existing Arriel, Arrius, Makila, and Aneto product lines. The deal was reported at around £230 million and transferred all RTM322 intellectual property, the Bordes production line, and customer support contracts to Safran Helicopter Engines.

Is the MTR390 (Tiger engine) the same as the RTM322?

Not quite — the MTR390 is a smaller derivative built by a separate consortium (MTU, Turbomeca, Rolls-Royce). It uses RTM322 core technology but with reduced flow, fewer stages, and around 1,200 shp output, matched to the Tiger's lighter weight. Think of it as a younger sibling sharing DNA rather than the same engine in a different installation. The two engines are not interchangeable.

How many engines does each helicopter use?

The AW101 Merlin uses three RTM322s in a triple-engine arrangement (unique among modern medium helicopters, dictated by anti-submarine endurance and one-engine-out-over-water safety). The NH90 uses two. The Tiger uses two MTR390 derivatives. No production helicopter has used a single RTM322 — the engine sits in the heavy-lift class where multi-engine redundancy is standard.

Will the RTM322 be replaced?

Not in the near term. Safran's growth roadmap pairs the existing RTM322 with the new Aneto-class engine (2,500-3,000 shp range, used in the Airbus H160M Guépard and Leonardo AW189K) but treats them as complementary rather than substitute. RTM322 production continues at Bordes through at least the 2040s in support of NH90 and AW101 fleets, while a hybrid-electric demonstrator programme is exploring future propulsion approaches for the 2030s and beyond.

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