TM 1-1520-238-T-7
10–199
10–72. GRAVITY REFUELING/DEFUELING – MAINTENANCE OPERATIONAL CHECK (cont)
10–72
WARNING
During gravity refueling/defueling operations set REFUEL VALVE switch to
OPEN on refueling panel (fig. 10–73) prior to opening fuel cell filler cap.
This prevents cap and/or fuel being forced out of filler neck by NIU
pressurized air in fuel cell, and prevents fuel from splashing on personnel.
Failure to do so could cause injury or death.
CAUTION
To prevent discharging aircraft battery, ensure that all non-essential
electrical equipment is OFF. Failure to comply could result in damage to
equiptment.
Do not use battery if status of charge is low.
Do not exceed 20 minute limit to complete this maintenance operational
check.
3. Complete the maintenance operational check as follows:
Task
Result
a. On refueling panel (fig. 10–73), set FUEL
QTY switch to IND ON. AFT and FWD
FUEL QTY indicator needles indicate fuel
loads in aft and forward fuel cells.
If AFT FUEL QTY indicator does not indicate aft fuel
load with FUEL QTY switch at IND ON, go to
paragraph 10–80.
If FWD FUEL QTY indicator does not indicate forward
fuel load with FUEL QTY switch at IND ON, go to
paragraph 10–81.
b. On refueling panel, set REFUEL VALVE
switch to OPEN. Refuel valve is heard to
open, REFUEL VALVE OPEN indicator is
lighted.
If REFUEL VALVE OPEN indicator is not lighted with
REFUEL VALVE switch set to OPEN, replace lamp
(TM 1-1520-238-23). If lamp is still not lighted, go to
paragraph 10–78.
c. On pilot caution/warning panel (fig. 10–74),
check that REFUEL VALVE OPEN indicator
is lighted.
If REFUEL VALVE OPEN indicator is not lighted with
REFUEL VALVE switch set to OPEN, replace lamp
(TM 1-1520-238-23). If lamp is still not lighted, go to
paragraph 10–79.
d. Unlock fuel cell filler cap locking tab
(fig. 10–73) and rotate counterclockwise to
open cap. Locking tab unlocks, and cap
rotates smoothly.
If locking tab is broken or cap does not rotate
smoothly, replace fuel cell filler cap. (Detach check
valve control cable from cap lanyard, and install new
cap from lanyard on check valve control cable).
