Engine start system components Flashcards
What is the basic starting procedure for all jet engines?
The basic starting procedure for all jet engines involves rotating the high-pressure compressor to provide sufficient air to support combustion, followed by ignition and fuel introduction, and maintaining starter assistance until the engine reaches self-sustaining speed.
What are the two essential systems required for starting a gas turbine engine?
The two essential systems required are the system to rotate the compressor and turbine to a sufficient speed and the system to ignite the air/fuel mixture in the combustion system.
Why must the starter continue to assist the engine even after lite-off occurs?
The starter must continue to assist the engine after lite-off to prevent engine deceleration or failure to reach idle speed, ensuring the engine achieves a self-sustaining speed.
What could happen if the starter is cut off before the engine reaches self-sustaining speed?
If the starter is cut off before the engine reaches self-sustaining speed, the engine may fail to accelerate to idle speed or decelerate, resulting in a hot start or hung start.
What are the main methods used to start gas turbine engines?
The main methods include electric starters, air turbine starters, and cartridge starters.
Describe how a cartridge starter works.
A cartridge starter uses a burning cartridge to generate high-velocity gases that drive a small impulse-type turbine. The turbine’s power output rotates the engine through a reduction gear and automatic disconnect mechanism.
What are the advantages of air starting systems on commercial jet engines?
Air starting systems are light, simple, and economical, with air supplied from an external source, auxiliary power unit (APU), or cross-feed from another engine.
How does an air starter motor transmit power to the engine?
An air starter motor transmits power through a reduction gear and clutch to the starter output shaft connected to the engine, driving the compressor during the start.
What is the function of the sprag clutch in an air turbine starter?
The sprag clutch engages automatically to transmit power from the turbine rotor to the engine, and it disengages when the engine reaches self-sustaining speed, allowing the rotor to coast to a halt.
What maintenance tasks are typically performed on air turbine starters?
Maintenance includes checking the oil level, inspecting the magnetic chip detector for metal particles, checking for leaks, and ensuring proper lubrication.
What are the components found in the turbine housing of an air starter?
The turbine housing contains the turbine rotor, rotor switch actuator, nozzle components, and a containment ring designed to dissipate energy in case of rotor failure.
How does a direct cranking electrical starter work on a gas turbine engine?
A direct cranking electrical starter is a DC electric motor coupled to the engine via a reduction gear and clutch. It cranks the engine until it reaches self-sustaining speed and automatically disengages.
What are the two main types of electric starting systems for gas turbine engines?
The two main types are direct cranking electrical systems and starter-generator systems.
What is the difference between a direct cranking starter and a starter-generator system?
A direct cranking starter is disengaged after engine start, while a starter-generator remains engaged and functions as a generator after the engine reaches self-sustaining speed.
What is the purpose of the undercurrent controller in a starter-generator system?
The undercurrent controller ensures the starter-generator operates until the engine reaches a sufficient speed to sustain combustion, then disengages the starting circuit.
what is the engine start sequence?
