Jet Propulsion

Ignition

Igniters

• They ignite the fuel-air mixture, but their operating conditions are entirely different. In a reciprocating engine, a relatively low-energy spark must jump across the electrodes of a spark plug every other revolution of the crankshaft.

• There are a few spark plug designs that are usable in all aircraft reciprocating engines, but because of the difficulty in igniting the fuel-air mixture in a turbine engine, igniters are tailored to the engine.

• Generally, an igniter designed for one engine will not function properly in another model.

The basic sequence of the start cycle

Starter

Motor

External

Gearbox

Starter

Motor

Output

Shaft

Clutch

Mechanism

Reduction

Gear

Turbine

Air

In

Air

Out

Air

Out

Starter

MotorExternal

Gearbox

Drive to

Engine Shaft