Ignition and Starting Systems Part 5 Flashcards
The number appearing on the ignition distributor block indicates the
sparking order of the distributor.
The purpose of staggered ignition is to compensate for
diluted fuel/air mixture around the exhaust valve.
What should be used to clean grease or carbon tracks from capacitors or coils that are used in magnetos?
Acetone.
Igniter plugs used in turbine engines are subjected to high intensity spark discharges and yet they have a long service life because they
do not require continuous operation.
What will be the result of using too hot a spark plug?
Preignition.
If staggered ignition timing is used, the
spark plug nearest the exhaust valve will fire first.
In a high tension ignition system, the current in the magneto secondary winding is
induced when the primary circuit is interrupted.
The spark occurs at the spark plug when the ignition’s
primary circuit is broken.
A clicking sound heard at engine coast-down in a pneumatic starter incorporating a sprag clutch ratchet assembly is an indication of
the pawls re-contacting and riding on the ratchet gear.
(Refer to Figure 5.) If wire No. 8 is broken or disconnected after starter rotation is initiated, and the power lever is advanced, the
starting sequence will continue normally.
Using a cold spark plug in a high-compensation aircraft engine would probably result in
normal operation.
(Refer to Figure 5.) Which malfunctions will allow the igniters to operate normally during start but be inoperative when tested?
Wire 14 or 15 is broken.
Spark plug fouling caused by lead deposits occurs most often
when cylinder head temperatures are relatively low.
Which of the following are included in a typical turbine engine ignition system?
Two igniter plugs, one exciter unit, and two high-tension igniter leads.
As an aircraft engine’s speed is increased, the voltage induced in the primary coil of the magneto
increases.
The greatest density of flux lines in the magnetic circuit of a rotation magnet-type magneto occurs when the magnet is in what position?
Full alignment with the field shoe faces.
Defective spark plugs will cause the engine to run rough at
all speeds.
The magnetic circuit of a magneto consists of a permanent multi-pole rotating magnet. The core is made of
soft iron.
An engine misses in both the right and left positions of the magneto switch. The quickest method for locating the trouble is to
check for one or more cold cylinders.
A certain nine cylinder radial engine used a noncompensated single unit, dual type magneto with a four pole rotating magnet and separately mounted distributors. Which of the following will have the lowest RPM at any given engine speed?
Distributors.
(Refer to figure 5.) Which malfunctions will allow the igniters to operate when tested but be inoperative during a start attempt?
1. Conductor No. 10 broken.
2. Conductor No. 11 broken.
3. Ignition relay inoperative.
4. Conductor No. 12 broken.
1 or 3.
When removing a shielded spark plug, which of the following is most likely to be damaged?
Core insulator.
The purpose of an under current relay in a starter-generator system is to
disconnected power from the starter-generator and ignition when sufficient engine speed is reached.
Igniter plugs used in turbine engines are subjected to high intensity spark discharges and yet they have a long service life because they
do not require continuous operation.
Inspection of pneumatic starters by maintenance technicians usually includes checking the
oil level and magnetic drain plug condition.
In addition to causing accelerated wear, dust or sand ingested by a reciprocating engine may also cause
silicon fouling of spark plugs.
Consider the statements below,
1. The platinum and iridium ground electrodes used on fine wire spark plugs are extremely brittle and can be broken if they are improperly handled or adjusted.
2. When gapping massive-electrode spark plugs, a wire gauge should be inserted between the center and ground electrodes while moving the ground electrode in order to avoid setting the gap too close. Regarding the above statements,
only no. 1 is true.
In a four-stroke cycle aircraft engine, when does the ignition event take place?
Before the piston reaches TDC on compression stroke.
Airflow to the pneumatic starter from a ground unit is normally prevented from causing starter overspeed during engine start by
activation of a flyweight cutout switch.
