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The Pilots Desk
US-FAA14 CFR 121.253

Powerplant fire protection

Read the official rule

This regulation identifies which areas of an aircraft must have fire protection systems and points to the specific requirements those systems must meet (found in sections 121.255 through 121.261).

The "designated fire zones" requiring protection are:

  • Engine accessory sections (areas containing components like generators, hydraulic pumps, and fuel controls attached to engines)
  • Any installation where the engine and accessory compartment aren't separated by a firewall
  • Areas housing auxiliary power units (APUs), fuel-burning heaters, and similar combustion equipment

In practical terms, this means Part 121 air carriers must install fire detection and extinguishing systems in these high-risk areas where fires are most likely to start. These zones contain hot components, fuel lines, and ignition sources, making them critical areas to monitor and protect. The regulation ensures that if a fire starts in these locations, the crew can detect it quickly and suppress it before it threatens the aircraft.

*This is a plain-English summary for study only. The official 14 CFR text on this page is controlling — always read the current regulation and consult a CFI.*

This is an original plain-English explanation for training and reference, not legal advice and not for navigation. Always rely on the current official rule linked above. Last reviewed June 20, 2026.