What is the maximum water content (H2O) in JP5 fuel for DFWD in parts per million (ppm)?

• A. 8 ppm
• B. 10 ppm
• C. 12 ppm
• D. 15 ppm

Answer: (B)

Water in JP-5 fuel is kept extremely low because even small amounts can cause big problems: water can separate from fuel, form ice in cold conditions that blocks fuel lines, accelerate corrosion, and promote microbial growth in storage. To protect aircraft fuel systems, the fuel must meet a strict maximum water content when tested with the DFWD (fuel-water detection) system. The standard limit is ten parts per million, which means only a tiny amount of water is allowed per million parts of fuel. This provides a safety margin against icing, fuel system fouling, and related issues while remaining practical for production and maintenance. Values lower than this are stricter than required, while higher values would let more water pass through and raise risk, so ten ppm is the correct, accepted maximum.