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F414

The F414 engine, although a new design, is derived from earlier engines, primarily the F412 designed for the A-12. The F414 is an advanced derivative of the F/A-18's current F404 engine family. The F414 Engine is a low bypass turbofan engine, with augmented thrust provided by the afterburner. The engine consists of six modules as follows: 1) Fan, 2) Compressor, 3) Combustor, 4) High Pressure Turbine, 5) Low Pressure Turbine, 6) Afterburner. The engine is controlled by a Full Authority Digital Engine Control (FADEC) which controls thrust modulation, fuel delivery, and governing. The new engine has increased thrust, an improved thrust-to-weight ratio of 9:1 and a 3- to 4-percent cruise-specific fuel consumption improvement over the F404-GE-400 engine. The F414 engine was conceived during studies begun in 1991 to develop an upgraded F/A-18 fighter with significant improvements in range and operational capability. Designated the F/A-18E/F, the Advanced Hornet is 25 percent larger than the currently operational F/A-18 Hornet - the US Navy's premier carrier based multi-role fighter. The F414 that powers it is a 22,000-pound thrust class augmented turbofan engine. The F414 engines provides 35 percent more thrust than the GE F404 engines used in the original F/A-18.

More importantly, the F414 provides significant thrust increases in areas of the flight envelope critical to a multi-mission aircraft like the F/A-18E/F. It has 30 to 40 percent more thrust in the heart of the flight envelope to give the F/A-18E/F the advantage during close-in aerial combat, 25 to 30 percent more thrust supersonically for high altitude air combat intercept missions and over 40 percent more thrust for low-altitude air-to-ground missions where high speeds to and from the target area greatly enhance aircraft survivability.

Advanced, but well proven technologies allow the F414 to stay the same length and maximum aft-end diameter of the original F404 while producing more thrust. The F414 fan provides 16 percent more airflow than the F404 fan, with improved bird strike and foreign object damage resistance features adopted from the F404/RM12 fan. Performance and reliability have been built into the new advanced power plant by carefully selecting the latest proven technology from the GE23A, F412, YF120 and other GE military and commercial engines.

In addition to proven technology, more than five million flight hours of F404 operational experience were factored into the F414 design. As a result, durability, reliability, and performance have been enhanced. The F414 has a 2000-hour hot section life and a 4000-hour specification life for all other engine rotating components and structure. Critical rotating disks, shafts and engine structure have been designed using GE's robust, damage-tolerant design practice. This delivers a three-fold improvement in low cycle fatigue compared to previously used design methods.

The F414 configuration has been carefully planned for low-risk development by selectively using proven component technologies. Integrally bladed disks, also called blisks, are used in the second and third stages of the fan, and the first three stages of the seven-stage compressor. These blisks provide a 53-pound, or 24-kilogram, weight savings over more conventional blade and disk dovetail joints. With fewer parts, blisks also improve overall engine reliability. Using blisk technology, the F414 has 484 fewer parts in the fan and compressor than the F404.

A compact, lightweight, annular combustor with 30 thousand laser-drilled cooling holes significantly lowers combustor wall temperatures for longer life. Sophisticated manufacturing equipment makes this design very affordable. Highly-loaded single-stage, air-cooled high and low pressure turbines use GE's latest single crystal alloys. Three dimensional viscous flow modeling helped increase low pressure turbine efficiency more than one percentage point over previous design methods. Thermal barrier coatings also enhance the durability of both turbines.

The F414 use GE's advanced air-cooled radial flameholder and spraybar system in the augmentor. This will increase flameholder life substantially when compared to the current F404 design. Durability of this design has been proven by achieving more than 6000 afterburner cycles, better than three times life requirements. The radial flameholders, nozzle secondary flaps and seals are also individually replaceable without having to disassemble the engine.

The engine-mounted dual-channel full authority digital engine control - or FADEC architecture provides the highest level of reliability and performance in a lightweight system. In addition, the FADEC provides advanced fault detection logic to identify and adapt to various system failures.

IHPTET technologies can reduce the F414 SFC by 4% and increase turbine life to 6,000 hours, providing a $2B savings in total ownership cost. These technologies could also be used to provide a 20% increase in thrust with a 2,000 hour turbine life. Improvements in component life and durability increase mean time between engine removals, leading to improved readiness and reduced maintenance cost. Two Stage, Forward Swept Fan with Blisk Rotors (first stage shown) increases airflow and pressure ratio 10% over the current three stage version, and reduces parts count, weight, and manufacturing costs. Laser shock peening and translation friction welded blade repair reduces the effects of foreign object damage and lowers repair costs. The Six Stage Compressor uses the latest 3-D aero and clearance control features to increase efficiency by 3%. Also included are ruggedized leading edges, 3-D compound blisk hubs, non-uniform vane spacing, and probabilistic design assessment to significantly increase durability and reduce high cycle fatigue. The Advanced High Pressure Turbine incorporates 3-D aero design, advanced cooling, and brush seals to increase efficiency by 2% and gas path temperature capability by 150F with current blade materials.

The F414 engine underwent extensive development testing as part of the US Navy's Engineering and Manufacturing Development program. Design effort was begun in January 1991. All major engine components were evaluated in full-scale rig tests prior to running the first test engine. These rig tests provided valuable time - as much as a year - to optimize the final component designs. The benefits were realized when the first F414 engine was tested in May 1993 and met all performance goals. The rig tests also helped to reduce development cycle time - the first engine was tested two and one-half years before first flight. This provided more time to find and fix problems during engine development, which reduced costs by minimizing design changes after production. By the time the F414 completed the Navy's Engineering and Manufacturing Development program in 1998, it had accumulated more than 10 thousand test hours on 14 engines.

The F414 engine program was the first major Navy aeropropulsion test program conducted at AEDC as a part of the transition of workload from the Navy's engine test facilities. Testing of the F414 began at AEDC in October 1993, only six months after the first F414 was tested at sea level in GE's facilities in Lynn, Mass.

F414 testing at AEDC includes altitude performance, and functional and operability testing. AEDC testing of the F414 was focused on achievement of three specific program milestones: Preliminary Flight Qualification test in May 1995; Limited Production Qualification tests in September 1996; and Full Production Qualification tests in September 1997. Flight testing of the Super Hornet began in November 1995. To speed the F414 test data analysis process, a high-speed link was established with the Navy's facility in Trenton, N.J., allowing the Navy engineers to have "virtual presence" at AEDC, analyzing the data in virtually real time. The same data were displayed at both Trenton and AEDC, allowing the Navy to evaluate the test results and provide test direction much more quickly than using traditional practices.

Much of the success of the F414 development program has been due to its innovative management and design approach. The Navy formed more than 40 Integrated Product Development Teams with representatives from each critical function and discipline. These teams have been directly involved in the design, procurement and testing of the F414's complex engine hardware. US Navy representatives have also been part of these teams so the contractors could benefit from the customer's insight as they progressed. Co-location of teams was critical to success. Being physically close together greatly enhanced communication and allowed teams to operate more effectively.

The Integrated Product Development Team approach is paying off. With F414 engine development 70 percent complete, design, manufacturing, procurement, and test cycle time reductions of 20 to 60 percent were seen on many components. Hardware re-work and scrap costs had fallen dramatically. As an example, the first test engine required only 25% of the re-work budget compared to previous programs. Also noteworthy, about 80% of all hardware for the first test engine came from production sources. The number of design changes was about two-thirds less than the historical average. All major program milestones were on or ahead of schedule. The best example of benefits of Integrated Product Development was demonstrated by the Afterburner and Exhaust Nozzle Team. They designed, developed, and fabricated the first afterburner and exhaust nozzle assembly for full-scale engine testing in just 14 months. This saved the F414 program 17 months compared to previous military engine programs.

The F414 engine work share concept is known as Government/Industry Logistics Support (GILS). GILS involves the Government performing all levels of maintenance with industry providing the majority of the logistics support, such as material management (parts support), training, support equipment, configuration management, etc. A GILS concept demonstration is planned for engine support during the aircraft OPEVAL phase. A long-term commitment to GILS is dependent on the success of the OPEVAL GILS demonstration. The current acquisition plan has organic support as the baseline logistics support with the GILS concept being investigated as a possible alternative.

Recognizing that the F/A-18E/F will assume new roles and missions over its lifetime, as well as face an uncertain and ever changing threat environment, GE designed the F414 with thrust growth potential to meet these anticipated needs. Already envisioned for the F414's first growth step was a 10 percent thrust increase that could be available by 2005. Increased performance would be achieved with an improved core having an all blisk compressor and higher temperature turbine alloys to withstand a modest temperature increase. The second growth step would provide 15 percent more thrust than the initial F414 - about 25,000 pounds of thrust (or roughly 111 kilo- Newtons ). This engine would use the improved Step A core with a larger fan and low-pressure turbine. It would still fit within the existing F/A-18E/F engine installation, however.

The final growth step - Step C - would produce an engine with 30 percent more thrust than the F414 - just under 29,000 pounds, or about 128 kilo- Newtons. This thrust level is nearly equal to the F110 Increased Performance Engine. To reach this impressive thrust level will demand further airflow growth from the fan, a modest temperature increase, a new two-stage low pressure turbine and a new afterburner.




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