FAA Powerplant Written Practice Test

What additional action must be taken to ensure safety when removing a turbine igniter plug?

1. Disconnect the low voltage lead and wait 30 seconds

2. Disconnect the low voltage lead and wait 1 minute

3. Disconnect the high voltage lead first

4. Only turn off the ignition switch

The correct answer is: Disconnect the low voltage lead and wait 1 minute

When removing a turbine igniter plug, it is critical to take specific safety precautions to ensure that no residual charge remains in the system that could lead to an accidental ignition. The correct procedure requires disconnecting the low voltage lead and waiting a minimum of one minute. This waiting period allows any stored electrical energy to dissipate and eliminates the risk of electric shock or an unintended spark during the removal process. Disconnecting the low voltage lead ensures that electrical current cannot flow into the igniter circuit, while the one-minute wait provides an added layer of safety by ensuring that capacitors (if present) have fully discharged. This practice reduces the potential for personal injury or damage to the equipment when handling the igniter plug. In comparison, waiting for just 30 seconds may not be sufficient, especially in systems with higher capacitance values, where residual voltage may still be present. Additionally, prioritizing the disconnection of the high voltage lead first could create a risk if precautions are not taken. Simply turning off the ignition switch does not guarantee that all electrical energy has been dissipated, as it may not address the risk posed by stored energy in the system.