What is the standard fuel settling time?

• A. 4 hours
• B. 2 hours
• C. 6 hours
• D. 8 hours

Answer: (A)

After fueling, the fuel in the tanks can still contain free water droplets and fine sediment. Letting gravity do its work allows that water to settle to the bottom of the tanks, where it can be collected and drained, and it also lets the fuel become stable enough for accurate quantity readings. Four hours is long enough for most of the free water to separate and for the fuel gauges to stabilize, which helps ensure you’re not drawing water into the engine and that your fuel measurements are reliable. Shorter times, like two hours, might not allow complete separation and stable readings, while longer times aren’t required by standard procedures and would unnecessarily delay operations. So the standard fuel settling time is four hours.