When can it be safe to re-energize aircraft electrical systems after a fire?

When can it be safe to re-energize aircraft electrical systems after a fire?

• A. Immediately after extinguishment.
• B. Only after a qualified person has confirmed safety and de-energized circuits; structural integrity verified.
• C. After cooling for 5 minutes, regardless of checks.
• D. After flight crew approves.

Answer: (C)

After a fire, heat and damaged insulation create a real risk when power is restored. Components that are still hot can reignite or fail if energized too soon. Allowing a brief cooldown helps heat dissipate and reduces the chance of arcing or further damage when power is reapplied. The guideline in this item sets a fixed cooling interval—about five minutes—as the initial, conservative step before re-energizing. This simple rule gives crews a safe, predictable pause and a better footing to perform any follow-up checks. While a full safety verification by a qualified person would still be part of the overall process, the cooling period is the essential first safeguard described here. Immediate energizing or relying solely on approvals without addressing the heat risk increases the chance of re-ignition or electrical faults.

After a fire, heat and damaged insulation create a real risk when power is restored. Components that are still hot can reignite or fail if energized too soon. Allowing a brief cooldown helps heat dissipate and reduces the chance of arcing or further damage when power is reapplied. The guideline in this item sets a fixed cooling interval—about five minutes—as the initial, conservative step before re-energizing. This simple rule gives crews a safe, predictable pause and a better footing to perform any follow-up checks. While a full safety verification by a qualified person would still be part of the overall process, the cooling period is the essential first safeguard described here. Immediate energizing or relying solely on approvals without addressing the heat risk increases the chance of re-ignition or electrical faults.