Fuel control system

Fuel system





hydro-mechanical, and the acceleration and speed control and pressure ratio control systems, which are mechanical. With the exception of the pressure ratio control system, which uses a gear-type pump, all the systems use a variable-stroke, multi-plunger type fuel pump to supply the fuel to the spray nozzles.

8. Some engines are fitted with an electronic system of control and this generally involves the use of electronic circuits to measure and translat changing engine conditions to automatically adjust the fuel pump output. On helicopters powered by gas turbine engines using the free-power turbine principle (Part 5), additional manual and automatic controls on the engine govern the free-power turbine and, consequently, aircraft rotor speed.

A pressure relief valve type oil system,Pressure relief valve system,INTRODUCTION,Lubrication

Lubrication :

INTRODUCTION :

Fig. 8-1 A pressure relief valve type oil system.

1. The lubrication system is required to provide lubrication and cooling for all gears, bearings and

splines. It must also be capable of collecting foreign matter which, if left in a bearing housing or gearbox,

can cause rapid failure. Additionally, the oil must protect the lubricated components which are manu-

fractured from non-corrosion resistant materials. The oil must accomplish these tasks without significant

deterioration.

2. The requirements of a turbo-propeller engine are somewhat different to any other types of aero gas
turbine. This is due to the additional lubrication of the heavily loaded propeller reduction gears and the
need for a high pressure oil supply to operate the propeller pitch control mechanism.

3. Most gas turbine engines use a self-contained re circulatory lubrication system in which the oil is
distributed around the engine and returned to the oil tank by pumps. However, some engines use a
system known as the total loss or expendable system in which the oil is spilled overboard after the engine
has been lubricated.

LUBRICATING SYSTEMS