2548H INSTRUCTION MANUAL
56-101-00420 Rev. C
Ch. 3
Nov
/
07
/
14
Page 12 of 33
B. Methods of Calibration
There are two (2) methods of Fuel Quantity System calibration:
Method 1: Dry Tank (PREFERRED)
Method 2: Wet Tank (ALTERNATE)
(1) Method 1 (Preferred)
The Dry Tank method of calibration is done without fuel in the tank(s) and with
the Tank Unit(s) dry. A capacitance value is substituted for an equivalent amount
of fuel (full) in the tanks. The indicator is then adjusted to display this full level of
fuel. (This method is more accurate since the indicator’s zero (0/) indication is set
to the actual empty tank value thus ensuring the integrity of the system’s empty
level.)
(2) Method 2 (Alternate)
The Wet Tank method of calibration is done with fuel in the tanks. The Tank Unit
is “electrically” removed from the Fuel Quantity Indicating System. Simulated
values for both EMPTY and FULL adjustments are made to the indicator. The
actual empty setting is questionable. Accuracy is sacrificed by using simulated
values.
However, if correct, current dry tank capacitance values are available for the
aircraft by serial number, these values should be used for the indicator EMPTY
adjustment. The user may than add the ADD FOR FULL value to the current dry
tank value to get the FULL adjustment value. (Refer to the Aircraft Maintenance
manual.)
Note:
Method 2 should be used
only
as a TEMPORARY measure. Method 1
should then be done at a more suitable time.
