Fuel tank vent explosion protection

This regulation requires certain large transport aircraft to have systems that prevent fuel tank explosions caused by flames entering through fuel tank vents.

It applies to turbine-powered transport category airplanes certified after January 1, 1958, that carry either 30+ passengers or have a payload capacity of at least 7,500 pounds.

For newer aircraft—those receiving their original airworthiness certificate after August 23, 2018—operators must have FAA-approved flame propagation prevention systems installed and working. These systems protect against external flames (such as from an engine fire or lightning strike) traveling through the vent system into the fuel tank's vapor space, where they could ignite fuel vapors and cause a catastrophic explosion.

This is a safety requirement addressing lessons learned from past accidents. Operators cannot fly affected aircraft manufactured after the 2018 cutoff date unless these protective systems are present and functioning.

*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.*