J.P. Instruments Fuel Scan 450M 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
• Solid-state pulse generating rotor
fuel flow transducers
• Instantaneous fuel flow rate
• Total amount of fuel consumed
• Fuel consumed by each engine
• Total fuel remaining
• Time to empty at the current fuel
flow rate
• Fuel required to next waypoint
• Fuel reserve at next waypoint
• Nautical miles per gallon
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-450M Fuel Scan uses small turbine transducers that
measure the fuel flowing into each 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 engines have consumed. Prior to engine
start you inform the FS-450M 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-450M 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.