IGNITION AND STARTING PART 3

Using a cold spark plug in a high-compression aircraft engine would probably result in. normal operation. a fouled plug. detonation.

The purpose of an under current relay in a starter-generator system is to. provide a backup for the starter relay. disconnect power from the starter-generator and ignition when sufficient engine speed is reached. keep current flow to the starter-generator under the circuit capacity maximum.

Which of the following are included in a typical turbine engine ignition system?. Two igniter plugs, two transformers, and two intermediate ignition leads. Two igniter plugs, one exciter unit, and two low-tension igniter leads. Two igniter plugs, one exciter unit, and two high-tension igniter leads.

Which statement is correct regarding the ignition system of a turbine engine?. The system is normally de-energized as soon as the engine starts. It is energized during the starting and warmup periods only. The system generally includes a polar inductor-type magneto.

When performing a magneto ground check on an engine, correct operation is indicated by. a slight increase in RPM. no drop in RPM. a slight drop in RPM.

Shielding is used on spark plug and ignition wires to. protect the wires from short circuits as a result of chafing or rubbing. prevent outside electromagnetic emissions from disrupting the operation of the ignition system. prevent interference with radio reception.

In the aircraft magneto system, if the P-lead is disconnected, the magneto will be. on regardless of ignition switch position. grounded regardless of ignition switch position. open regardless of ignition switch position.

Hot spark plugs are generally used in aircraft powerplants. with comparatively high compression or high operating temperatures. with comparatively low operating temperatures. which produce high power per cubic inch displacement.

Magneto breaker points must be timed to open when the. rotating magnet is positioned a few degrees before neutral. greatest magnetic field stress exists in the magnetic circuit. rotating magnet is in the full register position.

The primary advantage of pneumatic (air turbine) starters over comparable electric starters for turbine engines is. a significant lack of wear to the commutator. that it does not disengage until the engine reaches idle. its high power-to-weight ratio.

Advantages of dual ignition in aircraft engines are a more complete and quick combustion of the fuel, provides a backup magneto system, and. permitting the use of lower grade fuels. increasing the intensity of the spark at the spark plugs. increasing the output power of the engine.

Magneto breaker point opening relative to the position of the rotating magnet and distributor rotor (internal timing) can be set most accurately. during the magneto-to-engine timing operation. during assembly of the magneto before installation on the engine. by setting the points roughly at the required clearance before installing the magneto and then making the fine breaker point adjustment after installation to compensate for wear in the magneto drive train.

What test instrument could be used to test an ignition harness for suspected leakage?. A high tension lead tester. A high voltage dc voltmeter. A high amperage dc ammeter.

Which of the following, obtained during magneto check at 1,700 RPM, indicates a short (grounded) circuit between the right magneto primary and the ignition switch?. BOTH -- 1,700 RPM, R -- 1,625 RPM, L -- 1,700 RPM, OFF -- 1,625 RPM. BOTH -- 1,700 RPM, R -- 0 RPM, L -- 1,700 RPM, OFF -- 0 RPM. BOTH -- 1,700 RPM, R -- 0 RPM, L -- 1,675 RPM, OFF -- 0 RPM.

When testing a magneto distributor block for electrical leakage, which of the following pieces of test equipment should be used?. A high-tension harness tester. A continuity tester. A high-range ammeter.

What is the relationship between distributor and crankshaft speed of aircraft reciprocating engines?. The distributor turns at one-half crankshaft speed. The distributor turns at one and one-half crankshaft speed. The crankshaft turns at one-half distributor speed.

The secondary coil of a magneto is grounded through the. ignition switch. primary coil. ground side of the breaker points.

(Refer to Figure 5.) With power applied to the bus bar, what switch changes will allow the ignition exciters test switch to function?. Engine master switch, battery switch, and power lever switch. Engine master switch, start switch, and test switch. Engine master switch and ignition switch.

The E-gap angle is usually defined as the number of degrees between the neutral position of the rotating magnet and the position. where the contact points close. where the contact points open. of greatest magnetic flux density.

A safety feature usually employed in pneumatic starters that is used if the clutch does not release from the engine drive at the proper time during start is the. flyweight cutout switch. spring coupling release. drive shaft shear point.

If staggered ignition timing is used, the. spark plug nearest the exhaust valve will fire first. spark will be automatically advanced as engine speed increases. spark plug nearest the intake valve will fire first.

(Refer to Figure 5.) The type of system depicted is capable of operating with. external power only. either battery or external power. battery power and external power simultaneously.

The purpose of a safety gap in a magneto is to. prevent burning out the primary winding. protect the high-voltage winding from damage. prevent burning of contact points.

The magnetic circuit of a magneto consists of a permanent multi-pole rotating magnet. The core is made of. hard steel. soft iron. electrical steel.

A clicking sound heard at engine coast-down in a pneumatic starter incorporating a sprag clutch ratchet assembly is an indication of. gear tooth and/or pawl damage. one or more broken pawl springs. the pawls re-contacting and riding on the ratchet gear.

The numbers appearing on the ignition distributor block indicate the. sparking order of the distributor. relation between distributor terminal numbers and cylinder numbers. firing order of the engine.

What are two parts of a distributor in an aircraft engine ignition system?. Block and rotor. Coil and rotor. Block and coil.

The term 'reach,' as applied to spark plug design and/or type, indicates the. linear distance from the shell gasket seat to the end of the threads on the shell skirt. length of center electrode exposed to the flame of combustion. length of the shielded barrel.

How is the strength of a magneto magnet checked?. Hold the points open and check the output of the primary coil with an ac ammeter while operating the magneto at a specified speed. Check the ac voltage reading at the breaker points. Check the output of the secondary coil with an ac ammeter while operating the magneto at a specified speed.

When installing a magneto on an engine, the. piston in cylinder 1 must be a prescribed number of degrees before top center on the compression stroke. magneto breaker points must be just closing. piston in cylinder 1 must be a prescribed number of degrees after top center on the intake stroke.

Magneto timing drift is caused by erosion of the breaker points and. excessive spark plug gap. wear of the cam followers. loss of magnetism in the rotor.

What is the approximate position of the rotating magnet in a high-tension magneto when the points first close?. Full register. Neutral. A few degrees after neutral.

Sharp bends should be avoided in ignition leads primarily because. weak points may develop in the insulation through which high tension current can leak. ignition lead wire conductor material is brittle and may break. ignition lead shielding effectiveness will be reduced.

In an aircraft ignition system, one of the functions of the capacitor is to. regulate the flow of current between the primary and secondary coil. facilitate a more rapid collapse of the magnetic field in the primary coil. stop the flow of magnetic lines of force when the points open.

The constrained-gap igniter plug used in some gas turbine engines operates at a cooler temperature because. it projects into the combustion chamber. the applied voltage is less. the construction is such that the spark occurs beyond the face of the combustion chamber liner.

When internally timing a magneto, the breaker points begin to open when. the piston has just passed TDC at the end of the compression stroke. the magnet poles are fully aligned with the pole shoes. the magnet poles are a few degrees beyond the neutral position.

Failure of an engine to cease firing after turning the magneto switch off is an indication of. an open high tension lead. an open P-lead to ground. a grounded magneto switch.

A safety feature usually employed in direct-cranking starters that is used to prevent the starter from reaching burst speed is the. stator nozzle design that chokes airflow and stabilizes turbine wheel speed. drive shaft shear point. spring coupling release.

When using an electric starter motor, current usage. is highest at the start of motor rotation. remains relatively constant throughout the starting cycle. is highest just before starter cutoff (at highest RPM).

Ignition check during engine runup indicates a slow drop in RPM. This is usually caused by. defective spark plugs. a defective high-tension lead. incorrect ignition timing or valve adjustment.

What is the radial location of the two north poles of a four-pole rotating magnet in a high-tension magneto?. 180° apart. 270° apart. 90° apart.

If an aircraft ignition switch is turned off and the engine continues to run normally, the trouble is probably caused by. an open ground lead in the magneto. arcing magneto breaker points. primary lead grounding.

Upon inspection of the spark plugs in an aircraft engine, the plugs were found caked with a heavy black soot. This indicates. worn oil seal rings. a rich mixture. a lean mixture.

(Refer to Figure 5.) If wire 8 is broken or disconnected after starter rotation is initiated, and the power lever is advanced, the. starting sequence will continue normally. starter will shut down, but the igniters will continue to fire. starting sequence will discontinue.