PRINCIPLES OF NAVAL ENGINEERING 



are supported by ball bearings assembled in the 

 mounting bores of the accessory case. 



Accessories always provided in the acces- 

 sory drive section include the fuel control, with 

 its governing device; the high pressure fuel oil 

 pump or pumps; the oil sump; the oil pressure 

 and scavenging pump or pumps; the auxiliary 

 fuel pump; and a starter. Additional acces- 

 sories which may be included in the accessory 

 drive section or which may be provided else- 

 where include a starting fuel pump, a hydraulic 

 oil pump, a generator, and a tachometer. Some 

 gas turbine engines are equipped with magnetos 

 for ignition and these magnetos are driven from 

 the accessory drive. Most of these accessories 

 are essential for the operation and control of 

 any gas turbine engine; however, the particular 

 combination and arrangement of engine-driven 

 accessories depends upon the use for which the 

 gas turbine engine is designed. 



Engine Systems 



The major systems of a gas turbine engine 

 are those which supply fuel, lubricating oil, and 

 electricity. 



FUEL SYSTEM.— The fuel system supplies 

 the specified fuel for combustion. The compo- 

 nents of a fuel system depend to some extent 

 upon the type of gas turbine engine; however, 

 the basic fuel oil system shown in figure 23-15 

 may be regarded as typical of a simple fuel 

 system. The engine-driven pump receives fil- 

 tered fuel from a motor-driven supply pump at 

 a constant pressure. The engine-driven fuel 

 pump increases the pressure and forces the fuel 

 through the high pressure filter to the fuel con- 

 trol governor in the fuel control assembly. The 

 fuel control governor provides fuel to the 



FUEL PRESSURE 

 GAGE 



NOZZLE SHUTOFF 

 VALVE 



I- 

 (- 





N 

 



z 

 >z 



L 

 E 

 S 



STARTIf<G FUEL 

 BYPASS VALVE 



GOVERNOR OUTLET LINE 



ENGINE-DRIVEN FUEL PUMP PRESSURE LINE 



— ■ EXCESS FUEL RETURN LINE 



+ + + -f STARTING FUEL BLEED LINE 

 [><I MANUAL SHUTOFF VALVES 



147.149 



Figure 23-15.— Fuel flow diagram for gas turbine engine. 



606 



