Checking Fuel Quantity Gauges; Checking Fuel Quantity Senders; Adjustment Of Fuel Gauges; Fuel Quantity Sender Resistance Limits Table - Piper Navajo Chieftain PA-31-350 Service Manual

NAVAJO CHIEFTAIN SERVICE MANUAL
9-12. CHECKING FUEL QUANTITY GAUGES.
a.
Completely drain the inboard and outboard fuel cells that relate to the gauge that is to be
checked. (Refer to Draining Fuel Cells, Section II.)
b.
Level the airplane longitudinally and laterally.
c.
Ascertain that the crossfeed and emergency shutoff valves are closed.
NOTE
The electrical system must supply 28 volts to the gauge to make
this check.
d.
Turn the master switch ON and observe the fuel quantity gauge. It should read empty with the
respective fuel selector lever at both the inboard and outboard ON positions.
e.
Add fuel to each cell in the amount of 10.0 U.S. gallons to the outboard cell and 14.0 U.S.
gallons to the inboard cell, to bring each cell to one-quarter its full capacity.
f.
Again move the selector lever to both ON positions and observe the gauge. At either position the
quantity pointer should align within one needle-width of the one-quarter gauge index wire.
g.
Continue to add fuel in increments of 10.0 and 14.0 U.S. gallons to the outboard and inboard
cells respectively for each quarter capacity of the cells. At each quarter increment, until full, check that the
quantity pointer aligns within one needle width of the index wire, with the selector lever at either ON position.
h. Should the gauge and the amount of fuel in the cell not correspond, the gauge may be calibrated per
paragraph 9-14.
9-13. CHECKING FUEL QUANTITY SENDERS.
a.
Disconnect the sender unit and check for the ohm readings noted in Table IX-I.
TABLE IX-I. FUEL QUANTITY SENDER RESISTANCE LIMITS
Unit Location
Float Position
Ohm Reading
Main & Auxiliary Inboard
Empty
0 to 0.5
Full
48 to 52
Main & Auxiliary Outboard
Empty
0 to 0.5
Full
38 to 42
Main & Optional Nacelle
Empty
0 to 0.5
Full
28 to 32
b.
The sender unit must be replaced if the above tolerances are not maintained.
9-14. ADJUSTMENT OF FUEL GAUGES. The fuel gauges have been calibrated at time of installation at
the factory and normally need not be recalibrated unless a gauge or cell sender unit has been replaced. Should
it become necessary to calibrate a gauge, the following procedure may be used.
CAUTION
Adjust the quantity gauge; do not try to change adjustments of
the sender units.
Revised: 10/15/82
FUEL SYSTEM
2K14