FAA Aviation Mechanic Powerplant (AMP)Reciprocating EnginesHard
During troubleshooting, a technician finds a magneto producing a weak, sputtering, blue spark accompanied by badly burned and pitted breaker points. Which component is most likely defective, allowing excessive arcing at the points and preventing rapid collapse of the magnetic field?
- AThe condenser (capacitor)
- BThe impulse coupling spring
- CThe distributor gear
- DThe primary coil winding
Show answer & explanationAnswer & explanation
Correct answer: A. The condenser (capacitor)
The condenser absorbs the surge of current at the instant the breaker points open, preventing arcing across the points and allowing the primary field to collapse rapidly for a strong induced secondary spark. A defective (open, shorted, or weak) condenser causes point arcing/burning and a weak, sputtering spark.
Why the other options are wrong
- B. A weak impulse coupling spring affects starting RPM boost, not spark quality or point condition.
- C. A worn distributor gear affects timing/spark distribution, not point condition or spark quality directly.
- D. A shorted primary winding would typically cause a complete loss of spark, not burned points specifically.
Magneto Condenser
A capacitor wired across the breaker points that absorbs the induced current surge at point opening, preventing arcing and enabling rapid primary field collapse for a strong spark.
- Located in parallel with breaker points
- Defective condenser causes arcing, burned points, weak spark
- Essential for rapid collapse of primary magnetic field
Memory trick: 'Condenser catches the spark surge before it burns the points'