AMT Reciprocating Engine Ignition Systems Questions and Answers

Question 1

What is the primary reason for using a dual ignition system on a certified aircraft reciprocating engine?

Accepted Answer

To provide redundancy for safety and improve combustion efficiency for better performance.

Answer

To reduce engine operating temperatures and decrease fuel consumption.

Answer

To eliminate the need for an impulse coupling during engine start.

Answer

To decrease the electrical load on the aircraft's main battery and alternator.

Question 2

During a magneto check at the specified RPM, a technician observes a significant RPM drop on the right magneto that exceeds the manufacturer's limits, while the left magneto check is normal. The engine runs rough when switched to the right magneto only. What is the most likely cause?

Accepted Answer

One or more fouled spark plugs on the right magneto's ignition harness.

Answer

A broken P-lead wire connected to the left magneto.

Answer

Incorrect internal E-gap timing in the left magneto.

Answer

A sheared impulse coupling on the right magneto.

Question 3

In a magneto ignition system, what is the specific purpose of an impulse coupling?

Accepted Answer

To produce a hot, retarded spark for engine starting.

Answer

To advance the ignition timing as engine RPM increases.

Answer

To pressurize the magneto for high-altitude operations.

Answer

To filter out radio frequency interference from the high-tension leads.

Question 4

The internal timing of a magneto is set by adjusting the breaker points to open at the 'E-gap' position. What does the E-gap represent?

Accepted Answer

The angular position of the rotating magnet a few degrees past neutral where the magnetic field flux is strongest.

Answer

The physical air gap between the rotating magnet and the pole shoes.

Answer

The clearance between the distributor rotor finger and the terminal.

Answer

The total electrical resistance of the primary winding.

Question 5

An aircraft engine operating at consistently high power settings is experiencing pre-ignition. A technician suspects the spark plugs may be a contributing factor. Which action is most appropriate?

Accepted Answer

Installing spark plugs with a colder heat range.

Answer

Installing spark plugs with a hotter heat range.

Answer

Increasing the spark plug electrode gap.

Answer

Decreasing the spark plug electrode gap.

Question 6

What is the primary function of the P-lead wire connected to a magneto?

Accepted Answer

To ground the primary circuit, thereby disabling the magneto.

Answer

To supply primary voltage from the aircraft bus to the magneto.

Answer

To carry the high-tension voltage to the distributor.

Answer

To provide a signal to the cockpit tachometer.