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Waiting period before touching an igniter plug lead

Aviation Mechanic Powerplant (AMP) practice question 6 of 11 on Ignition and Starting Systems. ACS element AM.III.H.R1 · difficulty: standard. Want to answer it in a timed quiz? Use the Aviation Mechanic Powerplant (AMP) practice mode.

Question bank updated 2026-09-22

QUESTIONAfter disconnecting the low-voltage primary lead from a capacitor discharge ignition exciter, how long should a mechanic wait before disconnecting the high-voltage cable from the igniter plug?

  1. AAt least thirty minutes
  2. BAt least one minute
  3. CAt least five seconds
Show the answer and explanation

Correct answer: B. At least one minute

  • A — incorrect No such waiting period appears in the procedure; the stated interval is far shorter.
  • B — correct The recommended procedure is to disconnect the low-voltage primary lead and wait at least one minute to permit the stored energy to dissipate.
  • C — incorrect A few seconds is not the interval given, and it does not allow the stored charge to bleed down.

BACKGROUND

A capacitor discharge ignition system stores its energy in capacitors inside the exciter unit, and that energy remains stored after electrical power is removed. Before disconnecting an ignition lead from an igniter plug, a good procedure is to disconnect the low-voltage primary lead from the exciter unit and wait at least one minute so the stored energy can dissipate. When ignition leads are removed from the engine, any remaining electrical charge in the system is discharged by grounding. The handbook cautions that the high energy level and voltage of turbine ignition systems can cause injury or death to anyone contacting an activated system.

STUDY TIP

Treat an exciter as live until the primary lead is off, one minute has passed, and the system has been grounded, no matter how long the engine has been shut down.

KEY POINTS

  • Disconnect the low-voltage primary lead, then wait at least one minute.
  • Ground the system to discharge any stored energy before removing leads.
  • Turbine ignition energy levels can injure or kill on contact.

SOURCES

  • sources/amp-powerplant/ch04.txt "Removal, Maintenance, & Installation of Ignition System Components" (Igniter Plugs, step 1)
Practice the Aviation Mechanic Powerplant (AMP) test →Timed 100-question exam, by ACS area, or review your misses. Free.
MORE ON IGNITION AND STARTING SYSTEMS

SkyDrill is not affiliated with the FAA. This is an original practice item based on FAA-H-8083-32B Aviation Maintenance Technician Handbook – Powerplant, and 14 CFR part 43. Regulations and handbooks are revised; confirm details against the current edition.