Fuel Filter Differential Pressure (Restriction) - Indicates the difference in fuel pressure between the inlet side and the outlet side of the fuel filter. As the fuel filter element becomes plugged, the difference in pressure between the two sides of the fuel filter increases.
For instructions on replacement of the secondary fuel filter elements, see this Operation and Maintenance Manual, "Fuel System Secondary Filter - Replace" topic.
For instructions on replacement of the primary fuel filter elements, see this Operation and Maintenance Manual, "Fuel System Primary Filter - Replace" topic.
The nominal fuel filter differential pressure for new primary fuel filters during normal engine operation is approximately
Replace the primary fuel filter elements when the fuel filter differential pressure reaches
The nominal fuel filter differential pressure for new secondary fuel filters during normal engine operation is approximately
Replace the secondary fuel filter elements when the fuel filter differential pressure reaches