Transfer Faults

When the fuel stops moving, the engines are rarely in immediate danger — the feed chain is the pumps' job. What transfer faults attack is access (fuel stuck in tanks it cannot leave) and the CG (the trim schedule broken). That is why most of this family reads as "reconfigure, re-plan the fuel, accept a penalty" rather than LAND ASAP. This article covers the horizontal family (outer/centre to inner), the vertical family (trim line), and one famous impostor.

 horizontal (feed logistics)              vertical (CG logistics)
 ├─ FUEL OUTR TO INR FAULT                ├─ FUEL AFT XFR FAULT
 ├─ FUEL CTR TK XFR FAULT                 │    └─ ⚠ the refuelling impostor
 └─ FUEL CTR TO INNER FAULT               ├─ FUEL ABNORM MAN FWD XFR
                                          └─ FUEL T TANK XFR FAULT (the deep one)
 housekeeping: FUEL MAN XFR COMPLETED

1. Horizontal family

FUEL OUTR TO INR FAULT — the gravity transfer from the outers has failed. Fix: take it manual.

(six-tank, centre not empty:) L + R CTR PUMPS ... OFF   ← clear the inlet path
OUTR TK XFR ........................................ ON
▸ both outers empty: OUTR TK XFR AUTO · CTR PUMPS ON
Note: the caution recalls when the centre tank empties.

Why switch the centre pumps off first? The inner-tank inlet valves are shared plumbing: pumped centre flow and gravity outer flow compete for the same doors, and gravity loses. Clear the path, drain the outers, restore. The recall on centre-empty is the system reminding you the inners now have no replenishment source.

FUEL CTR TK XFR FAULT — centre empty, a pump still running: the dry-run alert (pumps — thermal fuses are non-resettable).

L + R CTR PUMP ............ OFF
◆ trim empty:   T TANK FEED ISOL · T TANK MODE AUTO
◆ trim not empty: T TANK MODE FWD
   ▸ trim empty: FEED ISOL · MODE AUTO · CTR PUMPS ON

The curious middle step — re-running pumps you just secured — is the six-tank forward-transfer geometry: trim fuel travels trim → centre → (centre pumps) → inners. The procedure parks the trim fuel in the centre, then uses the suspect pumps for one last delivery. With fuel present it is not a dry run; the trim fuel is worth the wear.

FUEL CTR TO INNER FAULT — transfer anomaly or an inlet valve stuck open:

L + R CTR PUMPS ............ OFF
WHEN EITHER INR < 17 T:
   OUTR TK XFR (if outer inlet open) ....... ON
   CTR TANK XFR (if low-level sensor failed) MAN
   L + R CTR PUMPS .......................... ON
▸ centre empty: CTR TANK XFR AUTO

The 17 t gate again (room in the inners), then condition-matched fixes: an outer inlet stuck open → use it (drain the outers through the door that won't shut); level sensing dead → open the centre's door manually.

2. The impostor — a false AFT XFR FAULT during refuelling

FUEL AFT XFR FAULT itself is two words of procedure (crew awareness) and one real cost: aft transfer inoperative, the cruise CG stuck forward, a fuel-burn penalty of the order the T TANK procedure quotes (~1 %). But the FCOM gives it a dedicated temporary-behaviour note:

"The FUEL AFT XFR FAULT alert may spuriously trigger during the refuelling when the fuel pumps are ON."

The three-step truth test: ① wait — refuel mode OFF should clear it by itself; ② cycle — all fuel pumps OFF then ON; ③ believe it — still displayed = real alert, logbook entry, MEL. On the line this alert during a turnaround is usually the impostor — but the third step is the discipline: "probably false" and "treated as false" are different things.

3. FUEL ABNORM MAN FWD XFR — "you're asking gravity to flow uphill"

Triggers when a manual forward transfer is commanded with the trim pump failed (or not fitted) and pitch above 3.4° for more than 30 s — the crew-facing twin of the automatic 3.4°/1 min inhibit (forward transfer):

SPD < 270 kt or in climb:    T TANK MODE AUTO · T TANK FEED AUTO   (wait)
SPD > 270 kt and not climbing: T TANK MODE FWD · T TANK FEED OPEN  (transfer)

270 kt and level is simply "nose low enough for gravity to work." The exception list is the teaching point: the alert does not trigger during inner-tank low level or an aft-CG warning — when the forward transfer is a rescue, the system lets you run it however badly the geometry cooperates. The alert polices efficiency, not emergencies.

4. The deep one — FUEL T TANK XFR FAULT

Aft or forward trim transfer failed. The trunk procedure:

T TANK MODE ............ FWD
T TANK FEED ........... OPEN     (fuel-burn penalty ≈1 %; the OPEN row
                                  appears for isolation-valve / level-sensor cases)
Note 1: trim pump failed → gate behind SPD > 270 kt and not in climb
Note 2: manual FWD with FEED OPEN — do not drain the trim tank
        below ≈200 kg: keep the trim pipe wetted to preserve
        the APU's normal supply

Branches that earn their lines:

• an aft transfer valve stuck open → monitor the trim quantity during the forward transfer; if it does not decrease (fuel recirculating aft as fast as it leaves) → MODE AUTO, FEED ISOL, and declare T TK FUEL UNUSABLE → the trapped-fuel endgame (trim-tank fuel unusable);
• (six-tank) CG forward of 32 % → the two-step forward transfer (trim to 2.4 t while the centre works down, finish when the centre empties — the 32 % member of the three-criteria warning);
• trim empty → MODE AUTO and FEED AUTO (or ISOL if an aft valve is stuck open — a leaky door stays locked).

The AMM's failure-response matrix behind this alert adds three quantified behaviours worth knowing: a single-tank FQI failure turns the manual two-step into a timed one (first step 15 minutes continuous; second after 60 minutes if the trim low-level sensor is wet — when the gauge dies, the clock substitutes); a stuck-closed auxiliary forward-transfer valve makes the FCMS de-energise the transfer pumps and reroute the forward flow through the trim-pipe and centre-inlet valves; and a double high-level-sensor failure in one inner keeps that tank's inlet shut, forcing one-sided forward transfer until the 3 000 kg imbalance warning hands the problem to the crossfeed.

FUEL MAN XFR COMPLETED — the family's housekeeping note: a manual transfer switch left on after its tank emptied. Switch back to AUTO.

Self-test

[!note]- Q1. Why does the OUTR TO INR fix start by switching the centre pumps off? Pumped centre flow and gravity outer flow share the inner inlet valves — and gravity cannot compete. The pumps yield until the outers have drained.

[!note]- Q2. In CTR TK XFR FAULT with trim fuel aboard, why do the secured centre pumps come back on? Six-tank forward transfer routes trim fuel through the centre tank; the pumps make the final centre→inner delivery. With fuel present it is no longer a dry run.

[!note]- Q3. Recite the false-AFT-XFR-FAULT truth test. Refuel mode OFF — should self-clear; all pumps OFF/ON — should clear; still displayed — real, logbook, MEL. Always finish step three.

[!note]- Q4. When does ABNORM MAN FWD XFR deliberately stay silent? Inner-tank low level or aft-CG warning — rescue transfers are never interrupted; the alert only polices wasteful ones.

[!note]- Q5. Forward transfer running, trim quantity not falling, an aft valve known stuck open. Verdict? The fuel is recirculating aft through the stuck valve — stop (MODE AUTO), lock the line (FEED ISOL), declare the trim fuel unusable and go to the trapped-fuel procedure.

Key takeaways

References

• FCOM PRO-ABN-FUEL (all six procedures, both configurations); DSC-28-100 (temporary abnormal behaviour note).
• AMM 28-27-00 §7.E (failure-response matrix: timed steps, reroutes, sensor cases).
• The shared-door and "polices efficiency" framings are integrative synthesis.

Independent study material, not an Airbus publication and not endorsed by the manufacturer. Always defer to the current operator FCOM, FCTM, and QRH for operational use.