Full Authority Digital Control systems are the premier control system. The applications are limitless (motorcycles to power plants and everything in between). Over the past 15 years, the US Navy has worked successfully with Woodward Governor Co. to develop and implement FADC LOCOPs for use in a number of applications including DDG and CG class ships gas turbine generators. The FADC LOCOPs provide closed loop control features as did the old analog control systems. But the FADC LOCOPs add the ease and speed of control improvements via software change, constant data monitoring/recording and network connectivity. The network connectivity advantage is still early in development; however this key feature of the control system opens up many doors. Distance support can be taken to an entirely new level via the network. Imagine a setup where if the control detects an abnormality…an email containing control system data gets sent to the blackberry of the In Service Engineering Agent (ISEA) so immediate action can be taken to maintain system reliability and reduce overall system cost. This future can help save money and avoid expensive catastrophic failure via condition based maintenance. In this future, it is possible that eventually the ISEA suggestions can be prompted right back to the FADC LOCOP so the sailors onboard can communicate with the ISEA via the FADC LOCOP. Essentially, every ship could have the ISEA (or an ISEA representative)onboard 24 hours a day seven days a week via FADC LOCOP communicating over a network. The system is not this evolved yet. However, several Navy Programs are working in conjunction towards a similar future including DDG Modernization and Integrated Condition Assessment System (ICAS) via Maintenance Engineering Library Server (MELS) and Integrated Performance Analysis Reports (IPAR). FADC LOCOPs are the foundation upon which these improvements rely to be implemented…thus the premier control system.

The U.S. Navy operates Rolls Royce 501-K34 powered Gas Turbine Generators (GTGs) on DDG 51 Class destroyers. The design of these GTGs has evolved significantly over the course of the shipbuilding program. One significant change is that GTGs on DDG 51 to 90 are rated to provide 2,500 KW while those on DDG 91 and follow are rated at 3,000 KW. The 3,000 KW rating has been accepted by the Navy and demonstrated on several new GTGs during qualification testing. However, test results indicate that one area where very little performance margin exists is full load transient response. This paper discusses extensive transient testing performed on a DDG 51 Class GTG at the U.S. Navy’s Land Based Engineering Site (LBES) in Philadelphia, Pennsylvania. It details control system modifications that optimize performance and explores changes to GTG transient response that result from operation with a new type of 501-K34 fuel nozzle.

The U. S. Navy uses Rolls-Royce gas turbines for ship service power on the DDG-51 class destroyer and the CG-47 class cruiser. Both engines have duplex thermocouples (T/Cs) and redundant T/C harnesses for turbine temperature monitoring and control. One harness provides an average of all the installed T/Cs, while the other provides the full authority digital control (FADC) with an individual signal from each. The legacy FADC algorithm allows up to four T/Cs to be out of average on the individual harness. Any additional T/C failures will cause the control to ignore the entire individual harness and rely on the averaging harness alone. This logic has inadvertently led to multiple over-temp conditions and subsequent engine removals. A change to control logic has been developed that aims to prevent these over-temp scenarios and is currently being introduced to the fleet. This paper will discuss in depth the cause of the over-temp, the examination of the control logic and the correction that is designed to prevent it from recurring.

Naval Surface Warfare Center, Carderock Division - Ship Systems Engineering Station (NSWCCD-SSES) successfully completed testing of a new Full Authority Digital Control (FADC) system for gas turbine control. This system will be back-fit onto Model 139 Ship Service Gas Turbine Generator Sets (SSGTGs) on the U.S. Navy’s Ticonderoga (CG-47) class cruisers. The FADC will be a direct replacement of the original Model 139 Local Operating Panel (LOCOP) and will control the Allison 501-K17 gas turbine. The new control system provides for standardized installation across a wide variety of existing configurations. The development program leveraged off of the design work done for the AG9140 FADC currently being installed on DDG 51 Class ships. The result was a state-of-the-art system ready for shipboard installation in a short period of time, providing commonality of look and feel across platforms. This paper describes the CG-47 FADC and details the development and testing conducted on a Model 139 SSGTG at the NSWCCD-SSES DDG 51 Gas Turbine Land Based Engineering Test Site (LBES). The test program included all modes of SSGTG operation, including starts, shutdowns, and generator operations under varying load conditions.