When working around capacitor discharge ignition systems, what safety precaution is essential?

• A. The spark energy is low; no special precautions needed.
• B. If capacitors are still charged after power is disconnected, there is a danger of a high energy spark; consult the maintenance manual for how long to wait before working on the system.
• C. Ground the aircraft frame only.
• D. Always disconnect the battery and ignore the maintenance manual timings.

Answer: (B)

Capacitor discharge ignition systems store a lot of energy in their capacitors. Even after you disconnect the power, those capacitors can remain charged and capable of delivering a high-energy spark when you work on the system. That’s why the essential safety step is to consult the maintenance manual for the exact duration to wait before proceeding. The manual specifies the safe wait time so the capacitors can discharge through approved paths, reducing the risk of a dangerous arc or shock. Merely grounding the frame or disconnecting the battery does not guarantee the energy is gone, and ignoring the prescribed timing can leave you exposed to a strong, potentially injurious spark. Following the manual’s wait time is the correct precaution for safe CDI work.