HYDRAULIC PUMP LOW PRESSURE • Hydraulics

NNC

ConditionCondition

Pression sortie pompe < 1 300 PSI — voyant LOW PRESSUREPump output pressure < 1,300 PSI — LOW PRESSURE light

ObjectifObjective

Distinguer LP EDP vs EMDP, bus lost vs vraie pompe — avant d’ouvrir Urgence pour les étapes.Distinguish EDP vs EMDP LP, bus loss vs real pump — before opening Emergency for steps.

LOW PRESSUREAB

SeuilThreshold< 1,300 PSI InhibitionInhibitEngine Fire Switch pulled EDP flow22–36 USG/min EMDP flow~6 USG/min

(*) Voyant inhibé Engine Fire Switch tiré.(*) Light inhibited with Engine Fire Switch pulled.

On GND

MEL 29-04 / 29-05 [System A/B Pump Low Pressure Indication] = voyants overhead seulement — pas indicateur pression ni pompe.MEL 29-04 / 29-05 [System A/B Pump Low Pressure Indication] = overhead lights only — not pressure indicator or pump.

Si LOW PRESSURE à la mise ON (EMDP), après start (EDP) ou taxi-out → pompe insuffisante. Ne pas décoller — NOGO!If LOW PRESSURE illuminates when switching ON (EMDP), after engine start (EDP), or during taxi-out → insufficient output. Do not takeoff — NOGO!

In FLT

S’assurer qu’il n’y a pas de fuite. Voir Hydraulic System et vérifier les quantités.Make sure there is no leak. See Hydraulic System and verify quantities.

Indication clignotanteBlinking indication

CauseCause

A/B pressurisés air manifold. Vol froid prolongé : gel condensation → cavitation.A/B pressurized by manifold air. Prolonged cold flight: frozen condensation → cavitation.

IndicesCues

LP intermittent · EMDP OH occasionnel · qty↑ (moussage)Intermittent LP · occasional EMDP OH · qty↑ (foaming)

Duct

Duct basse → Duct Pressure Low/High/Split. Gel → descendre air plus chaud.Low duct → Duct Pressure Low/High/Split. Freeze → descend warmer air.

DébitsFlow

EDP 22–36 USG/min · EMDP 6 USG/min

Panne pompe · On TOPump failure · On TO

On TO

EDP A · TO

EMDP peut ne pas monter le train. LGTU ne s’engage pas (N2 bas Eng 1).EMDP may not raise gear. LGTU will not engage (low N2 Eng 1).

Gear

Down/transit → lever DOWN, retourner. FMC ignore drag — +50 % fuel · PI LRC GEAR DOWN.Down/transit → lever DOWN, return. FMC ignores drag — +50% fuel · PI LRC GEAR DOWN.

EDP OFF

Via N2 gearbox · OFF = solénoïde blocking valve · DC Bus 1/2.Via N2 gearbox · OFF = solenoid blocking valve · DC Bus 1/2.

P6-2AB

Trip → impossible de dépressuriser.Trip → cannot depressurize.

Pannes composéesCompound Failures

Fire Switch tiré côté concerné : système perdu sans Master Caution ni LOW PRESSURE EDP — vérifier la pression.Same-side Fire Switch pulled: system lost without Master Caution or EDP LOW PRESSURE — verify pressure.

Fire Switch non tiré : EDP en moulinet peut tenir la pression jusqu’au ralentissement — configurer atterrissage tôt ; retarder NNC LOSS OF SYSTEM.Fire Switch not pulled: windmilling EDP may hold pressure until slowdown — configure for landing early; delay LOSS OF SYSTEM NNC.

EMDP OH coupé = système perdu. Abex : possible réengagement après refroidissement. Vickers : coupure auto → LP + OH ensemble.Switching off overheated EMDP = system lost. Abex: may re-engage after cooling. Vickers: auto power remove → LP + OH together.