TM 1-1520-238-T-7
Change 8
10–160.9
10–48A.
FUEL QUANTITY SYSTEM – CAPACITANCE AND INDICATING TEST
10–48A
(USING PSD 60-1AF TEST SET) (cont)
Task
Result
NOTE
For older model aircraft the foward tank capacitance tolerance may be
increased to 1.0 pf.
e. Subtract #1 FWD T cable (fig. 10–70.7)
capacitance (step 2.k.) from #1 FWD tank
capacitance. Calculated capacitance value
should be 66.3 0.8 pf.
If adjusted capacitance value is not within required
tolerance, go to paragraph 10–65.
Example:
66.1 pf
Actual indication on test set LCD indicator
- 0.3 pf
#1/FWD T cable capacitance
65.8 pf
Calculated value
5. Perform fuel quantity system forward tank indicator test as follows:
a. On test set (fig. 10–70.5), rotate SELECT
switch to LOZ-HIZ.
NOTE
The PSD 60-1AF test set indicates “over range” above 10,000 megohms by
flashing three colons and displaying four zeros (fig. 10–70.6).
b. Allow test set to stabilize for 30 seconds.
Verify test set LCD indicator displays greater
than 20 megohms.
c. Rotate SELECT switch to the following
positions and verify test set LCD indicator
displays greater than one megohm in each
position. LOZ-SHLD, HIZ-SHLD,
SHLD-GND, LOZ-GND and HIZ-GND.
If LOZ and HIZ values are not within required
tolerance, go to paragraph 10–47.
d. Detach T cable #1/FWD LOZ and HIZ leads
from TANK UNITS LOZ and HIZ
receptacles.
e. Attach T cable #1/FWD LOZ lead to
INDICATOR LOZ receptacle.
f. Attach T cable #1/FWD HIZ lead to
INDICATOR HIZ receptacle.
NOTE
Do not attach T cable #1/FWD CP lead.
g. Set test set FUNCT switch to MEASURE
INT.
h. Set test set SELECT switch to TU.
