General Electric T700

General Electric T700. The General Electric T700 and its commercial counterpart, the CT7, are a family of turboshaft and turboprop engines known for their ruggedness, reliability, and high power-to-weight ratio. Developed in the late 1960s and entering service in the 1970s, the engine was designed to meet stringent requirements from the United States Army for a new generation of utility and attack helicopters. Its modular design and resistance to foreign object damage have made it a benchmark for military and commercial rotary-wing propulsion worldwide.

Development and design

The T700's development was initiated under the United States Army's Utility Tactical Transport Aircraft System (UTTAS) program, which sought a new multi-role helicopter to replace the aging Bell UH-1 Iroquois. General Electric's design team, competing against Avco Lycoming, focused on creating an engine with exceptional durability in austere environments, leading to innovations like a centrifugal particle separator for inlet protection. The engine's core architecture features a five-stage axial compressor coupled with a single-stage centrifugal compressor, an annular combustor, and a two-stage gas generator turbine driving a two-stage free power turbine. This modular construction, championed by engineers at General Electric, allows for rapid field maintenance and significantly reduces downtime, a critical factor for military operations. The design philosophy emphasized "more time on wing," directly responding to lessons learned from the Vietnam War regarding helicopter engine maintenance and vulnerability.

Operational history

The T700 entered operational service in 1978, powering the winning UTTAS contender, the Sikorsky UH-60 Black Hawk. It quickly proved its worth during the invasion of Grenada and the invasion of Panama, where its reliability under demanding conditions was noted. The engine's most extensive combat proving ground came during the Gulf War and subsequent operations in Afghanistan and Iraq, where Black Hawks and AH-64 Apaches (using the derivative T700-GE-701) performed countless missions in high-heat and dusty environments. Its navalized version, the T700-GE-401, became the standard powerplant for the Sikorsky SH-60 Seahawk, serving with the United States Navy, the Royal Australian Navy, and other allied fleets globally. The T700 family has accumulated tens of millions of flight hours across multiple branches of the United States Armed Forces and international operators.

Variants

The primary military variants include the initial T700-GE-700 for the UH-60A and AH-64A, and the upgraded T700-GE-701 series with improved hot-day performance for the UH-60L and AH-64D. The T700-GE-401 series powers naval helicopters like the SH-60B/F. The more powerful T700-GE-701C and -701D engines feature advanced materials and digital controls, developed for the UH-60M and AH-64E. The commercial offshoot, designated the CT7, powers aircraft like the AgustaWestland AW139, Sikorsky S-70i, and CASA/IPTN CN-235. A turboprop version, the CT7-9, was developed for the Saab 340 and CASA C-295. Specialized derivatives were also developed, such as the Rolls-Royce Turbomeca RTM322, a joint venture with Rolls-Royce and Turbomeca.

Specifications (T700-GE-701C)

* **Type:** Twin-spool turboshaft * **Length:** 47 in (1,200 mm) * **Diameter:** 25 in (640 mm) * **Dry weight:** 458 lb (208 kg) * **Compressor:** 5-stage axial plus 1-stage centrifugal * **Combustors:** Annular * **Turbine:** 2-stage gas generator, 2-stage free power * **Maximum power output:** 1,994 shp (1,487 kW) * **Overall pressure ratio:** 17:1 * **Specific fuel consumption:** 0.373 lb/(shp·h) (227 g/(kW·h)) * **Power-to-weight ratio:** 4.35 shp/lb (7.15 kW/kg)

Applications

The T700 and CT7 are the propulsion heart of numerous iconic aircraft. Key military applications include the Sikorsky UH-60 Black Hawk for the United States Army and international forces, the Sikorsky SH-60 Seahawk for anti-submarine and utility roles, the Bell AH-1Z Viper for the United States Marine Corps, and the Bell AH-1 SuperCobra. It also powers the Sikorsky HH-60 Pave Hawk combat search and rescue helicopter and the Sikorsky MH-60 Jayhawk used by the United States Coast Guard. Commercially, the CT7 engine family is found on the AgustaWestland AW139 medium twin helicopter, the Sikorsky S-70i international Black Hawk, and fixed-wing aircraft like the Saab 340 regional airliner. Licensed production and assembly have occurred in facilities globally, including those operated by IHI Corporation in Japan and KAI in South Korea.

Category:Aircraft engines Category:Turboshaft engines Category:General Electric aircraft engines