Ignition and Starting Systems Flashcards
What is the main advantage of a magneto ignition system over a battery ignition system for an aircraft reciprocating engine?
A magneto has its own source of electrical energy and is not dependent upon the battery.
What is an all-weather spark plug?
A shielded spark plug that has a recess in the shielding in which a resilient grommet on the ignition lead forms a watertight seal.
What is meant by the reach of a spark plug?
The length of the threads on the spark plug that screw into the cylinder head.
What is the difference between a hot spark plug and a cold spark plug?
A hot spark plug has a long path for the heat to travel between the nose core insulator and the spark plug shell. In a cold spark plug, the heat has a shorter distance to travel and the spark plug operates cooler than a hot spark plug.
What is the advantage of fine-ware spark plugs over massive electrode spark plugs?
Fine-wire spark plugs have a firing end that is more open than that of a massive electrode spark plug. The open firing end allows the gases that contain lead to be purged from the spark plug so they will not form solid lead contaminates.
Why is it important that the spark plugs be kept in numbered holes in a tray when they are removed from an engine?
Spark plugs tell a good deal about the internal condition of the cylinders from which they were taken. By knowing they cylinder from which each spark plug came, the mechanic can take the proper action when a spark plug indicates such conditions as detonation or overheating.
Why is it important that a torque wrench always be used when installing spark plugs in an aircraft engine?
If the spark plugs are not put in tight enough, there is the possibility of a poor seal; if they are put in too tight, there is danger of cracking the insulation or damaging the threads on the spark plug or the cylinder.
What kind of gauge should be used to measure the electrode gap in aircraft spark plugs?
A round wire gauge.
What is a shower of sparks ignition system?
An ignition system that uses an induction vibrator to send pulsating DC into a set of retard breaker points on one of the magnetos. This provides a hot and retarded spark for starting the engine.
What is an impulse coupling, and how does it work?
An impulse coupling is a spring-loaded coupling between a magneto shaft and the drive gear inside the engine. When the engine is rotated for starting, the impulse coupling locks the magnet so it cannot turn. The spring in the coupling winds up as the crankshaft continues to turn, and when the piston is near top center, the coupling releases and spins the magnet, producing a hot and retarded spark.
What are the three distinct circuits in a magneto system?
-Magnetic circuit
-Primary electrical circuit
-Secondary electrical circuit
What are the advantages of a solid-state magneto?
-No mechanical parts that wear
-Higher energy spark at low speeds
-No recurring inspection requirements
What is the purpose of a FADEC system?
FADEC is a digital electronic fuel control for a gas turbine engine that is functioning during all engine operations, hence full authority. It includes the EEC and functions with the flight management computer. FADEC schedules the fuel to the nozzles in such a way that prevents overshooting power changes and over-temperature conditions. FADEC furnishes information to the EICAS.
What kind of electric starting system is used on many of the smaller turbine engines?
A starter-generator.
Why are air-turbine starters superior to electric starters for large turbine engines?
They are light weight for the torque they produce.
Where does an air-turbine starter get its air for starting the engines on a jet transport airplane?
-APU
-GPU
-From a running engine
What prevents too high an air pressure from over speeding an air-turbine starter?
The air shutoff and regulating valve.
Where does an air-turbine starter get its lubricating oil?
It has a self-contained lubrication system with the oil held in the starter housing.
What device in an air-turbine starter warns an aviation mechanic if there are any metal chips or particles in the oil?
Magnetic chip detectors warn of any metal contamination in the oil.
What is the function of the capacitor in a magneto?
The capacitor minimizes arcing at the breaker points, and it speeds up the collapse of the primary current as the breaker points open.
What happens in a magneto ignition system when the ignition switch is placed in the Off position?
The primary circuit is connected to ground.
What is checked when a magneto is internally timed?
Internally timing a magneto consists of adjusting the breaker points so they will open at the instant the rotating magnet is in its E-gap position, and the distributor rotor is in position to direct the high voltage to cylinder number one.
In what position should the ignition switch be placed when using a timing light on the magnetos?
In the Both position.
What is the E-gap in magneto timing?
The E-gap angle is the position of the rotating magnet where the primary current flowing is the magneto coil is the greatest. The breaker points open when the rotating magnet is in its E-gap position.
