Jettison Faults

Two ways the jettison system fails, with opposite problems: it won't dump (a planning failure — your weight-reduction option just vanished), or it won't stop (an active failure — fuel leaving the aircraft uncommanded). Both procedures are short; both reach beyond the fuel panel into the flight's strategy. Jettison-equipped aircraft only (fuel jettison).

1. FUEL JETTISON FAULT — it won't dump

Trigger: a defuel valve failed open — the system detects that a jettison would also flow through plumbing it cannot control, and inhibits itself:

JETTISON NOT AVAIL

That is the whole ECAM line. The real procedure happens in the crew's planning: the rapid-weight-reduction option is off the table, so an overweight situation now resolves by holding to burn fuel (time) or overweight landing (performance — the OVERWEIGHT LDG considerations). The decision wants making early and sharing with ATC and dispatch: both alternatives consume something (minutes or margin) that shrinks as the situation develops.

Dispatch note: the jettison items in some operators' MEL are low-category — the aircraft may well have departed with this state pre-declared, which is exactly why the overweight/holding arithmetic belongs in the briefing rather than the surprise column.

2. FUEL JETTISON NOT CLOSED — it won't stop

Trigger: a jettison valve not confirmed closed after the dump was commanded off.

JETTISON ...................... OFF       ← normal shutdown first (ARM/ACTIVE off)
◆ IF JETTISON CONFIRMED (still flowing — two tests):
   · quantities still falling at an abnormal rate (~1 t/min order), or
   · visual: fuel streaming at the jettison outlets
     (the flap-track fairing positions)
   L + R CTR PUMPS ............ OFF       ← cannot close the door?
                                            cut the water main.
   ▸ WHEN EITHER INR < 17 T:
      CTR TANK XFR ............ MAN       ← recover what centre fuel you can
   CTR TK XFR BY GRVTY
   CTR TK UNUSABLE IF < 15 T

The logic chain deserves its name — starve the valve: the jettison's muscle is the centre pumps (fuel jettison); a valve that will not close stops mattering once nothing pressurises it. The price is the same bill as a double centre-pump failure (pump failures): centre transfer by gravity only, the last 15 tonnes in the centre tank written off as unusable, STATUS carrying centre pumps and aft transfer inoperative.

[!warning]- Confirm before you pay The pumps-off step is conditional on confirmed continued flow — the quantity trend or the visual. A valve position disagreement with no actual flow is an indication problem, and the 15-tonne bill should not be paid for it. The two tests are cheap; run them first.

The fuel-planning update after the pumps go off: usable fuel = FOB − (centre below 15 t), with the half-boxed FOB doing the visual subtraction (controls and ECAM) — and the diversion plan re-run on the new number.

Self-test

[!note]- Q1. Why does a stuck-open defuel valve inhibit jettison? The two share plumbing; a jettison through an uncontrollable defuel path could not be stopped or directed. The system prefers no jettison to an unmanageable one.

[!note]- Q2. JETTISON NOT AVAIL appears during drift-down planning. What are your two remaining weight tools? Time (hold and burn) or performance (overweight landing per its procedure). Choose early — both get more expensive as the situation matures.

[!note]- Q3. How do you confirm a jettison that won't stop? Quantities falling at the abnormal rate (~1 t/min order) after JETTISON OFF, or fuel visibly streaming at the flap-track-fairing outlets. Either one earns the pumps-off step.

[!note]- Q4. Why do the centre pumps stop a jettison the valves cannot? The valves only direct flow; the centre pumps create it. No pressure, no dump — the same reason the feedline-burst drill kills pumps rather than chasing the breach.

[!note]- Q5. What does the pumps-off fix cost? The double-centre-pump bill: gravity-only centre transfer, centre fuel below 15 t unusable, aft transfer inoperative — re-plan usable fuel and the diversion accordingly.

Key takeaways

Point	Value
FAULT	self-inhibited (defuel valve open); JETTISON NOT AVAIL; plan = hold-to-burn or overweight landing
NOT CLOSED	OFF first; confirm flow (trend or visual); then centre pumps OFF
Starve the valve	no pump pressure = no dump, regardless of valve position
The bill	centre gravity transfer, <15 t unusable, aft transfer INOP
Discipline	confirm before paying the 15 t; brief MEL-deferred jettison before departure

References

FCOM PRO-ABN-FUEL FUEL JETTISON FAULT / FUEL JETTISON NOT CLOSED (procedures and STATUS).
Some operators' MEL 28-31 items (deferral categories).
The "starve the valve" framing and planning emphases 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.