Thrust Reverser Faults

Article 13 framed the reverser's engineering problem as guaranteeing it never opens itself in flight. This article is that insurance policy's reporting face, five alerts strong: it's broken (REV FAULT), maintenance has padlocked it (REV INHIBITED), hydraulic pressure arrived when it shouldn't (REV PRESSURIZED), a human selected it when they shouldn't (REV SET), and the door has actually cracked open (REV UNLOCKED — the heaviest of the five). The first four are mostly an accounting exercise — how to land without this reverser; UNLOCKED is the full script for flying home with a door ajar.

1. REV FAULT — the reverser is gone

"This alert triggers when the thrust reverser on one engine is lost. — If IDLE is automatically selected by the FADEC: ENG (AFFECTED) AT IDLE — THR LEVER (AFFECTED ENGINE) IDLE — Select thrust lever at idle, even if idle is automatically selected by the FADEC."

Note the even if: the lever goes to idle even when the FADEC already idled the engine — aligning lever position with actual thrust, the same logic as THRUST LOCKED in article 22. STATUS closes the account: landing-distance procedure applies, REV 1(2) inoperative (and GA SOFT where fitted).

2. REV INHIBITED — the receipt for the maintenance padlock

"This alert triggers when the reverser is inhibited by maintenance action. — Crew awareness."

This is the alert face of an MEL dispatch (synthesis, via article 13): with the reverser locked out for dispatch (the inhibition hardware), the system announces its own state. Seeing it should not surprise you — the point is that the dispatch paperwork and the ECAM corroborate each other. The account is the same book as FAULT's: landing distance computed without this reverser — which article 00 normalised long ago: performance calculations never counted the reversers in the first place.

3. REV PRESSURIZED — pressure at the lock's doorstep

"This alert triggers when the reverser system is pressurized, while reverser cowls are stowed and locked, with no deploy order (on ground). Note: (a) Alert inhibited in flight phases 3, 4, and 5 when ENG T/R third lock is not open. — THR LEVER IDLE."

The sensing source is the pressure switch downstream of the isolation valve (article 13) — the valve failed to close, or leaks, and hydraulic pressure now stands at the first lock's door. The inhibition note's logic (synthesis): through takeoff and climb, as long as the tertiary lock still bites — the door physically cannot open — the news that "pressure has arrived" is not worth interrupting the busiest phases. The only-what-you-need-to-know philosophy of articles 18/20 again. If the tertiary lock is open, the inhibition lifts — then you need to know immediately.

4. REV SET — reverse selected in flight

"This alert triggers when the reverse thrust is selected by the crew in flight. — THR LEVER (AFFECTED ENGINE) FWD THR."

The shortest procedure in the whole family — because the cause is your own hand (the alert incarnation of article 00's no reverse selection in flight). The mechanical interlock of article 08 blocks "reverse over forward thrust" but cannot block "reverse pulled after the lever reached idle". The handling is the correction.

5. REV UNLOCKED — the door ajar (the main course)

"This alert triggers when one reverser cowl is not locked in stowed position, with no deploy order. Other Inhibition: The alert is inhibited in the flight phase 4 and for the first 15 s of flight phase 5, except if the engine thrust is automatically set to idle."

Article 13's AUTO RESTOW script — above 5 %, idle the engine, command restow, hold the pressure — is already running in the background. The alert and procedure stack on top:

"In flight: MAX SPEED 300/.82 — ENG (AFFECTED) AT IDLE — THR LEVER IDLE (even if idle is automatically selected) — IF BUFFET: MAX SPEED 250/.70 / ENG MASTER (AFFECTED ENGINE) OFF. Note: 1. Lateral control (up to the equivalent of ½ stick) will be applied by the normal lateral law and thus spoilers will be extended and large aileron deflection will be used. However adequate roll control remains. 2. Do not follow beta and beta target. Apply full rudder and rudder trim towards the running engines."

The physics of the two-step speed limit (synthesis): a door ajar is an aerodynamic damage source — drag, disturbed flow, structural load. 300 kt / M 0.82 caps the aerodynamic force the door must carry. Buffet means the gap is churning the airflow and the structure is protesting — slow to 250 / M 0.70 and shut the engine down: with that side carrying neither thrust difference nor jet efflux, the load on the door is minimised.

"Do not follow the beta target" is the deepest counter-intuition in this article (synthesis): the beta target's algorithm assumes a clean thrust asymmetry — the ordinary single-engine case of article 25. A cracked-open reverser door creates an asymmetry of drag and disturbed flow; trim to the target and you trim in the wrong direction. The procedure retreats to first principles: full rudder and rudder trim toward the running engines, roll for heading. And note 1 reassures along the way: the lateral law will spend up to half-stick of authority (spoilers out, large aileron) — adequate roll control remains.

STATUS completes the approach picture: VLS + 15 kt — "both to increase lateral control and to maintain the approach angle-of-attack at a reasonable value … a reduction in lift may result from this failure" — the gap has spoiled that side's lifting body, so both axes get margin. In the buffet case, FLAP LVR 2 + GPWS FLAP MODE OFF; fuel imbalance monitoring; engine 1 shut down brings SLATS SLOW (article 25); CAT 3 SINGLE ONLY.

6. The five in one table

7. Scenario walk-throughs

Cruise, REV UNLOCKED. First, read what the system already did — auto-idle, restow command, holding pressure (article 13's script). Your actions stack on top: speed cap, lever aligned, buffet watch.

Buffet appears. 250 / M 0.70, MASTER OFF, and the approach account recomputes: FLAP 2, VLS + 15, distance.

Dispatched with the reverser locked out; REV INHIBITED lights after takeoff. Match it to the dispatch release — the landing-distance figure was already in the briefing.

REV PRESSURIZED lingers after normal reverse on landing. Article 13's normal hold-pressure-after-restow state versus the fault state is a maintenance call — hand it over with the timeline.

Self-test

[!note]- Q1. MEL-locked reverser, and ECAM shows REV INHIBITED — abnormal? Normal — the maintenance inhibition announcing itself. Corroborate with the release paperwork; landing distance is computed without that reverser.

[!note]- Q2. Takeoff roll (phase 4), the reverser system leaks pressure — immediate alert? No — inhibited in phases 3/4/5 while the tertiary lock is not open (a door that physically cannot open doesn't interrupt the busy phases). The moment the tertiary lock opens, the inhibition lifts.

[!note]- Q3. Light buffet after UNLOCKED — two actions? Speed to 250 / M 0.70, and MASTER OFF on the affected engine — minimising the aerodynamic load and jet disturbance on the cracked door.

[!note]- Q4. Why is the beta target forbidden after UNLOCKED? The target assumes a clean thrust asymmetry; the ajar door creates a drag-and-turbulence asymmetry — following it trims the wrong way. Full rudder and trim toward the running engines, roll for heading.

[!note]- Q5. Why VLS + 15 on approach? Double compensation — more lateral control authority, and the failure may have cost lift on that side, so the approach angle of attack stays reasonable. In the buffet case add FLAP 2 and GPWS FLAP MODE OFF.

Key takeaways

References

• FCOM PRO (engine abnormal procedures: REV FAULT / REV INHIBITED / REV PRESSURIZED with its inhibition note / REV SET / REV UNLOCKED complete section with both notes and full STATUS) — quoted verbatim; other-engine-type entries excluded per type discipline.
• Mechanisms via article 13: the three locks, the isolation-valve pressure switch, AUTO RESTOW, the inhibition hardware.
• Integrative synthesis (marked in text): the MEL-face reading of INHIBITED; the inhibition logic of PRESSURIZED; the two-step speed physics; the drag-asymmetry explanation of the beta-target prohibition.

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.