J.P. Instruments Fuel Scan 450 Pilots Guide - Manual (Page 3)

Section 1 - Introduction
Product Features

Fuel quantity measured in gallons,
liters, or pounds

Low fuel quantity alarm

Low fuel time alarm

GPS interface—bi-directional
serial interface

Automatic K-factor calculation

Solid-state pulse generating rotor
fuel flow transducer

Instantaneous fuel flow rate

Total amount of fuel consumed

Total fuel remaining

Time to empty at the current fuel
flow rate
Fuel Management
Without a means of measuring fuel flow, you must rely on the
aircraft fuel gauges or total time of flight. Aircraft fuel gauges are
notoriously inaccurate (they are only required by the FAA to read
accurately when displaying empty). And measuring time of flight is
only an approximation, and assumes a constant fuel flow rate for
each phase of flight.
The FS-450 Fuel Scan uses a small turbine transducer that
measures the fuel flowing into the engine. Higher fuel flow causes
the transducer turbine to rotate faster which generates a faster pulse
rate. Because the transducer turbine generates thousands of pulses
per gallon of fuel, it can measure with high resolution the amount
of fuel that the engine has consumed. Prior to engine start you
inform the FS-450 Fuel Scan of the known quantity of fuel aboard,
and it will keep track of all fuel used.
For fuel calculations to be accurate, it is imperative that you inform
the FS-450 of the correct amount of fuel aboard the aircraft. Do not
rely on fuel flow instruments to determine fuel levels in tanks. Refer
to original fuel flow instrumentation for primary information.