(1) Do a check of and replace, if necessary, the items of the left-wing surge-tank scavenge system that follow:
NOTE : During aircraft operations on the ground and in flight, fuel
____ can collect in the vent/surge-tank. If this occurs, a jet pump scavenge system moves the fuel into the related wing-tank outer-cell. If the jet pump 66QM is inoperative, the fuel-level in the left-wing vent/surge-tank can increase until it is above the level of the center-tank vent (duct/outlet-pipe at RIB22). Fuel can then flow through the center-tank vent and enter the center tank by the effect of gravity.
(a) The jet adaptor assembly (Ref. AMM TASK 28-21-53-000-003) and (Ref. AMM TASK 28-21-53-400-003).
(b) The scavenge jet pump (66QM) (Ref. AMM TASK 28-21-53-000-001) and (Ref. AMM TASK 28-21-53-400-001).
(c) The check valve (37QM) (Ref. AMM TASK 28-21-43-000-003) and (Ref. AMM TASK 28-21-43-400-003).
(d) The jet-pump pressurized-line, between the fuel-manifold (adjacent to the check valves 33QM and 34QM, in-board of RIB2) and the jet-pump 66QM.
(e) The jet-pump suction-line, between the suction inlet pickup point in the left-wing vent/surge-tank and the jet-pump 66QM.
(f) The jet-pump (output/discharge) pipe-line, between the jet-pump 66QM and the fuel discharge (outlet) adjacent to the intercell transfer valve 28QM (outboard of RIB15).
(g) Repair/replace all the unserviceable fuel pipes and connections (Ref. AMM TASK 28-00-00-000-001) and (Ref. AMM TASK 28-00-00-400-001).
(2) Do the Inspection of the (Center Tank) Overpressure Protector 96QM (Ref. AMM TASK 28-12-41-200-002).
NOTE : The function of the overpressure protector 96QM is to protect
____ the center tank structure from possible damage. The operation of the overpressure protector 96QM will safely release the (unwanted) pressure to the atmosphere through the left wing tank ventilation system. The defects that follow (and/or) can cause the over pressure protector 96QM to break/operate:
- the center tank vent pipe is blocked
- the pressure relief valve 97QM cannot open, or cannot open quickly enough or sufficiently enough to release the (unwanted) pressure safely to the atmosphere through the right wing tank ventilation system.
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(a) If the overpressure protector 96QM is serviceable:
- do a leak test of the RIB1 for leaks between the center tank and the left wing collector cell (Ref. AMM TASK 28-11-00-790-003).
1 Repair all the leaks:
_
- (Ref. AMM TASK 51-76-12-300-001)
- (Ref. AMM TASK 51-76-12-300-002)
- (Ref. SIL 57-0086).
(b) If the (frangible) overpressure protector 96QM has operated (is broken), it is important do all the steps that follow to find what caused it to break.
NOTE : The reasons why a burst disc can break are as follows:
____
- a defective/unserviceable disk (non standard) that breaks below the (its) correct operating pressure
- a serviceable disk that operated because the pressure difference between the center tank and the adjacent left wing tank was more than the correct safe operating pressure.
1 Replace the PROTECTOR-OVERPRESSURE, CTR TK (96QM) (Ref. AMM
_ TASK 28-12-41-000-003) and (Ref. AMM TASK 28-12-41-400-003).
2 Do a check of the pressure relief valve 97QM as follows:
_ a Get access to the pressure relief valve 97QM (Ref. AMM TASK
_
28-12-41-200-002).
b Do a visual check of the pressure relief valve 97QM to see
_
if it:
- has become blocked
- can open (functionally operate) with a full and free movement.
c If necessary, remove any blockage/obstruction or replace
_ the VALVE-PRESSURE RELIEF, CTR TK (97QM) (Ref. AMM TASK 28-25-45-000-001) and (Ref. AMM TASK 28-25-45-400-001).
3 Do an inspection of the center tank vent pipe (Ref. AMM TASK
_
28-12-00-200-001).
a If necessary, replace any damaged or blocked section(s) of
_ the center tank vent pipe.
4 Do a check of the center tank refuel valve 10QU as follows:
_ a Remove the center tank refuel valve 10QU.
_
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