2a) How does the APU produce the required starting air supply.
b) How is the starting air supplied and controlled from the APU to the engine
c) Describe how the torque from the starter motor is transmitted to the engine rotating assembly.
d) Describe the main functions and components of a high energy ignition system.
2a] how does the APU produce the required starting air supply.
The APU generates pneumatic power using bleed air extracted between the compressor and combustion chamber.
b] how is the starting air supplied and controlled from the APU to the engine
The starting air is supplied to the engines starters through a network of ducts and valves.
c] describe how the torque from the starter motor is transmitted to the engine rotating assembly.
Usually the starter motor turns the accessory gearbox, which rotates the jet engine shaft.
d] describe the main functions and components of a high energy ignition system.
An high-energy ignition systems obviously rely on igniters which supply electrical sparks in the combustion chamber for starting or maintaining the air/fuel combustion.
The igniters are powered by exciters generating high-voltage pulses from the aircraft electrical power system.
The exciters are controlled by the engine controllers according to the position of the fuel control ; ignition and fire switches.
