Ignition and Starting Systems practice questions

Answer: B) The magneto stays hot

• AIncorrect. Grounding stops it; an open lead leaves it live.
• BCorrect. With the ground path open, the magneto cannot be switched off and can fire if the prop is turned.
• CIncorrect. This is unrelated to mixture.
• DIncorrect. This is unrelated.

Answer: D) A round wire gauge

• AIncorrect. This checks timing.
• BIncorrect. Round wire gauges are preferred for curved electrodes.
• CIncorrect. This sets installation torque.
• DCorrect. Round wire gauges measure the gap accurately.

Answer: B) Electrode erosion

• AIncorrect. Turbine fuel has no lead.
• BCorrect. Igniter tips erode over time and are replaced at limits.
• CIncorrect. This is unrelated.
• DIncorrect. This is unrelated.

Answer: C) Reduces point arcing

• AIncorrect. That isn't its role.
• BIncorrect. It's an electrical part.
• CCorrect. It also speeds the primary field's collapse; a faster collapse gives a hotter spark.
• DIncorrect. That's the ignition switch.

Answer: A) Compressed air

• ACorrect. Air from the APU, ground cart or another engine spins the starter turbine.
• BIncorrect. That is an electric starter.
• CIncorrect. This is not used.
• DIncorrect. That is a cartridge or fuel-air starter.

Answer: A) Grounding the primary

• ACorrect. The switch grounds the primary circuit through the P-lead.
• BIncorrect. The primary is grounded.
• CIncorrect. This is the mixture control.
• DIncorrect. Magnetos do not need the battery.

Answer: B) During engine starting and for in-flight relight after a flameout

Once lit, turbine combustion sustains itself, so ignition is normally used only for starting and in-flight relight. Continuous ignition is selected only as a precaution in some conditions.

• AIncorrect. Turbine combustion keeps going on its own once lit. Continuous ignition is selected only as a precaution, for example in heavy rain or icing. It is not needed at normal cruise.
• BCorrect. The igniters light the fuel/air mixture during the start. After that, combustion sustains itself, so ignition is normally used only for starting and relighting. Continuous ignition is selected only as a precaution in some conditions.
• CIncorrect. Stable idle combustion sustains itself. Ignition is not turned on automatically just because the power lever is at idle.
• DIncorrect. Dry motoring means turning the engine with the starter, ignition off and no fuel, to clear fuel or vapor. Having ignition on would defeat the purpose.

Answer: C) Preignition

• AIncorrect. Reach does not affect the magneto.
• BIncorrect. This is unrelated.
• CCorrect. Exposed threads in the chamber collect carbon and become hot spots.
• DIncorrect. Reach does not change mixture.

Answer: A) To let a low-current cockpit switch control the heavy current flowing to the starter motor

The starter solenoid is a remote heavy-duty switch. A small cockpit switch energizes its coil, and its contacts carry the high starter current over short, heavy cables, which saves cable weight and reduces voltage drop.

• ACorrect. The cockpit switch or key energizes only the solenoid coil. The solenoid contacts then carry the high starter current, which can reach several hundred amperes, over short, heavy cables. This reduces overall cable weight and circuit voltage drop.
• BIncorrect. The solenoid is a switch, not a voltage regulator or resistor. When it closes, full battery voltage goes to the starter motor.
• CIncorrect. Disengagement is handled by the starter's engaging mechanism, such as an overrunning clutch or similar drive. The solenoid does not do it.
• DIncorrect. The solenoid does not limit current. Overuse is prevented by observing starter duty-cycle limits, and circuit protection guards against faults.

Answer: D) A retarded, hotter spark

• AIncorrect. It is an ignition device.
• BIncorrect. The spark is retarded and stronger.
• CIncorrect. It works only at starting.
• DCorrect. It snaps the magnet briefly to give a strong, late spark at low cranking speed.