for tolerances that are permitted between the fuel gauge reading and the actual fuel in the tank.
e. Add one (1) gal.of fuel to the tank and observe the gauge readings then add four (4) gal. to total five (5)
gal. Then add fuel in the amount of five U. S. gallon increments until the tank is full and observe the gauge
readings at each addition of fuel.
—NOTE—
It will be permissible to adjust the float assembly to obtain specified
tolerances. This adjustment may be accomplished per instructions
given in Paragraph 9-15.
9-16. CHECK AND ADJUSTMENT OF FUEL QUANTITY TRANSMITTER UNIT. (Refer to Figure 9-3)
a. If not previously removed, remove the transmitter unit to be checked from the fuel tank. (Refer to
b. Check and adjust the transmitter unit float position by using the following procedure:
1. Fasten the unit to a fabricated checking jig with washer and nuts. (This jig may be fabricated from
dimensions given in Figure 9-9.)
2. Ascertain that with the float arm down against the mechanical stop on the transmitter, the float is just
touching the top of a 0 .27 of an inch spacer block. Should the float not be touching the spacer or the float arm
is not against the bottom stop, adjust the arm stop of float assembly, by bending it where shown in Figure 9-3.
The entire surface of the float must be horizontal with the base of the jig.
c. Check the transmitter unit for correct resistance and dead spots by the following procedure:
1. Connect an ohmmeter to the transmitter unit and move the float arm to its bottom mechanical stop. The
ohmmeter should indicate the ohms resistance as indicated in Table IX-II.
2. Move the float arm to its upper mechanical stop and check the ohms resistance.
3. Check for dead spots by slowly moving the float arm from the bottom stop to the upper stop and back.
Watch the ohmmeter indicator; it should steadily move up and down the scale without fluctuation as the float arm
is moved.
4. If an incorrect resistance and/or dead spots are found, the transmitter unit should be replaced.
TABLE IX-I. TRANSMITTER/FUEL GAUGE TOLERANCES
Actual Fuel
Gauge Reading
in Tank(U.S. gal.)
(U.S.Gal.)
Full
15
12 to 17
10
7 to 12
5
2 to 6
1
0 to -2
0
Dot
*Plus one needle width
TABLE IX-II. FUEL QUANTITY TRANSMITTER CALIBRATION TOLERANCES
UNIT
POSITION
RESISTANCE
P/N P.S. 10013 - 11
EMPTY
3 ± .5 OHMS
(NITROPHYL FLOAT)
FULL
45 ± 2 OHMS
PIPER AIRCRAFT
PA-28-161 CADET
AIRPLANE MAINTENANCE MANUAL
Issued: FEBRUARY. 28, 1989
FUEL SYSTEM
2A16