Spoilers (2) — Ground Spoilers, the Extension Logic and Function Allocation

All six spoilers act as ground spoilers — the lift-dump that plants the aircraft on the runway for braking. Their automatic extension follows a clear armed / not-armed logic keyed to wheel speed, thrust levers, reverse and gear compression. This article covers that logic, the consolidated function-allocation map, and the actuation.

Spoilers 1 to 6 act as ground spoilers... The pilot arms the ground spoiler function by pulling the speedbrake control lever up into the armed position. — FCOM DSC-27-10-20

1. Arming

Per FCOM DSC-27-10-20, the crew arms the ground spoilers by pulling the speedbrake control lever up into the armed position. Arming determines which trigger extends them — thrust-levers-to-idle (armed) or reverse selection (not armed).

2. Full extension — the armed vs not-armed paths

Per FCOM DSC-27-10-20:

[!warning]- Not armed still works — reverse is the backup trigger Even if the crew forgets to arm, the ground spoilers still deploy — but the trigger becomes reverse selection instead of thrust-levers-to-idle (FCOM DSC-27-10-20). On a landing, an armed approach gives automatic extension at touchdown; unarmed, you get them when reverse is selected. The 72 kt wheel speed gate (RTO) ensures they only auto-deploy above taxi speed.

3. Partial extension and retraction

The ground spoilers partially extend when reverse is selected on at least one engine (other engine at idle) and one main landing gear is compressed. This partial extension, by decreasing the lift, will ease the compression of the second main landing gear, and consequently will lead to the normal ground spoiler extension.

Per FCOM DSC-27-10-20, a partial extension occurs with reverse on ≥1 engine and one main gear compressed — it dumps some lift to help the second main gear compress, which then triggers full extension. Retraction occurs when one thrust lever is above idle, or all thrust levers are at forward idle and the speedbrake lever is pushed down.

[!note]- Partial extension is a clever bootstrap for an asymmetric touchdown (integrative synthesis) If one main gear touches first (crosswind, bounce), the system partially extends to kill enough lift to settle the other gear (FCOM DSC-27-10-20) — which then gives the "both gears compressed" signal for full extension. It is a self-completing sequence that handles a one-wheel-first landing without waiting for both to compress on their own.

4. The consolidated function-allocation map

Across 22 and this article, the six spoilers' jobs:

[!note]- The outboard spoilers (4–6) carry the most jobs (integrative synthesis) Spoilers 4–6 do everything — roll, speedbrake, ground spoiler and MLA — which is why they are exempt from the symmetric-inhibit rule (22): losing their mirror would cost MLA and load relief. Spoiler 1 is the simplest (speedbrake/ground only, no roll). This allocation is worth memorising for reading the F/CTL page and failure effects.

5. Actuation

Per AMM 27-64-00, each spoiler has an electrohydraulic servo-control (hydraulic operation, electrical control) taking position commands from the FCPC/FCSC; each has an LVDT reporting spoiler position to its computer, and LVDT faults are detected by that computer (triggering the retract-to-zero fail-safe of 22).

6. Counterintuitive points

[!warning]- Forgetting to arm doesn't lose the ground spoilers — reverse deploys them Not-armed extension is triggered by reverse selection (FCOM DSC-27-10-20).

[!warning]- A single gear compressing triggers partial extension first Partial extension dumps lift to settle the second gear, then full extension follows (FCOM DSC-27-10-20).

Self-test

[!note]- Q1. How are ground spoilers armed, and which spoilers act as ground spoilers? Pull the speedbrake lever up to armed; all six (1–6) act as ground spoilers.

[!note]- Q2. Armed vs not-armed full extension on landing? Armed → both main gears touch down (thrust idle); not armed → both gears down + reverse on ≥1 engine.

[!note]- Q3. What causes partial extension, and why? Reverse + one main gear compressed — dumps lift to ease the second gear's compression, then full extension.

[!note]- Q4. Which spoilers carry the most functions, and the inhibit exemption? 4–6 (roll + speedbrake + ground + MLA) — exempt from the symmetric-inhibit rule.

Key takeaways

References

• FCOM DSC-27-10-20 (Architecture — Ground Spoiler Control) — spoilers 1–6 act as ground spoilers; armed by pulling speedbrake lever up; full extension RTO (armed: thrust levers idle with wheel speed > 72 kt; not armed: reverse on ≥1 engine), landing/bounce (armed: both main gears touch down; not armed: both gears down + reverse on ≥1 engine); partial extension (reverse + one main gear compressed, eases second gear); retraction (one thrust lever above idle, or all forward idle + speedbrake lever down); failed ground spoiler inhibits symmetric one.
• AMM 27-60-00 / 27-64-00 (Spoiler; Spoiler Hydraulic Actuation) — function allocation (roll 2–6, speedbrake/ground 1–6, MLA 4–6); each spoiler electrohydraulic servo-control (hydraulic operation, electrical control) commanded by FCPC/FCSC, LVDT position feedback with fault detection.

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.