General Electric will begin rig tests on the GE38-1B turboshaft for Sikorsky's CH-53K heavylift helicopter in 2008, leading to a first engine test in 2009 and flight tests in 2011. GE Aviation is developing the 7,500shp (5,600kW) GE38 under a contract covering six ground-test engines, more than 5,000 test hours and 20 flight-test engines for five development aircraft.
The GE38 is based on the GE27 technology demonstrator, run in the 1980s, and the T407 turboprop derivative for the Lockheed P-7 maritime-patrol aircraft, cancelled in the early 1990s. The core was adapted for the GE/Honeywell CFE738 business-jet turbofan. GE says the GE38 provides 57% more power, 18% better specific fuel consumption and has 60% fewer parts than the similarly sized GE T64 powering the existing CH-53E.
GE says the overall GE27 engine architecture, modular construction and high-pressure-ratio, single-spool compressor aerodynamics are used for the GE38, along with its cooling-flow strategy, lubrication system and bearing layout. The three-stage power turbine is based on the T407's, with a cooled first stage for durability and growth, and is a self-contained, sealed module to protect bearings and sumps from contaminants, GE says.
The GE38 design has been updated with new three-dimensional aerodynamics, cooling schemes and materials, providing about 45% more power than the T407 with the same airflow and fuel consumption, says GE. Hot-section cooling is designed to prevent sand clogging and improved materials and coatings are incorporated for erosion and corrosion resistance. A more rugged aerofoil leading-edge design is used to increase durability and compressor aerofoils have an erosion coating now being used in the T64.
Parts count is reduced by using blisks in the compressor, boltless rotors and low-solidity, high-work turbines that reduce blade and nozzle count. GE says many of the tubes and brackets are eliminated by using cored passages in the accessories. The full-authority digital engine control system will include prognostic health management. The triple-turbine CH-53K is to enter service with the US Marine Corps in 2015.
Source: Flight International
