AMP - Aviation Maintenance Technician Powerplant Practice Exam

What does the term "synchronous ignitions" refer to in dual ignition systems?

1. Utilizing a single ignition source for multiple cylinders

2. Timing both ignition systems to fire simultaneously

3. Firing one ignition system before the other for efficiency

4. Using high-voltage pulses for better performance

The correct answer is: Timing both ignition systems to fire simultaneously

The term "synchronous ignitions" in dual ignition systems refers specifically to the timing of both ignition systems to fire simultaneously. In aircraft engines equipped with dual ignition systems, each engine cylinder typically has two sources of ignition, usually from separate spark plugs and ignition systems. The purpose of having dual ignition is to enhance reliability and improve engine performance, especially during critical phases of flight. When both ignition systems fire at the same time, it ensures that there is a more consistent and complete combustion of the fuel-air mixture in the cylinders. This simultaneous firing boosts engine efficiency, reduces the likelihood of misfire, and provides redundancy; if one ignition system fails, the other can still ignite the fuel-air mixture, helping to maintain engine operation. In contrast, the other options do not accurately represent the concept of synchronous ignition. For instance, using a single ignition source for multiple cylinders does not involve dual ignition systems at all, while firing one ignition system before the other would not be considered synchronous, but rather sequential. Moreover, the use of high-voltage pulses specific to high-performance ignition systems is a different aspect of ignition technology that does not directly define synchronous ignitions.