Fuel flammability: flashpoint, explosive range and auto-ignition
- Pound for pound, aviation fuel more explosive than dynamite (TC AIM AIR 1.3.4).
- Differs from automotive fuel: car-filling rules insufficient for aircraft (TC AIM AIR 1.3.4).
Flashpoint: lowest temperature at which fuel vaporizes to form an ignitable mixture in air (TC AIM AIR 1.3.4.1).
| Fuel | Flashpoint | Result |
|---|---|---|
| AVGAS | well below freezing | Extremely flammable |
| Jet A-1 | 38 degrees C | Flammable vapours only at high ambient temperatures |
Explosive range (TC AIM AIR 1.3.4.1):
- Ignites only at 1 to 6 percent vapour by volume.
- Leaner or richer: will not burn.
- Sealed tank space above fuel can fall into lean, ignitable range in extreme cold.
Auto-ignition (TC AIM AIR 1.3.4.1):
- Jet A-1: 220 degrees C, ignites with no spark.
- Spill onto hot exhaust or brake can self-ignite.
Trap: Jet A-1's 38 degrees C flashpoint is not its 220 degrees C auto-ignition temperature.
References
- TC AIM AIR 1.3.4
- TC AIM AIR 1.3.4.1